Www.westar.org
April 17, 2006
The Honorable Stephen L. Johnson
Docket ID No. OAR-2001-0017
Air and Radiation Docket and Information Center
U.S. Environmental Protection Agency
Mailcode: 6102T
1200 Pennsylvania Avenue, NW
Washington, DC 20460
Dear Mr. Johnson:
We are writing to transmit the comments of the California Air Resources Board (ARB) and the Office of Environmental Health Hazard Assessment (OEHHA) on the recently proposed amendments to the National Ambient Air Quality Standards (NAAQS) for particulate matter (PM). We have substantial concerns regarding both the proposed fine particle (PM2.5) and coarse particle (PM10-2.5) standards.
Due to the serious nature of PM exposure in California and the extensive scientific literature demonstrating a clear association between PM exposure and adverse health effects, ARB adopted stringent standards for both PM2.5 and PM10 in 2002. We urge the U.S. Environmental Protection Agency (U.S. EPA) to take action to establish equally strong federal NAAQS for PM.
As noted in our previous communication, California has an annual-average PM2.5 standard of 12 μg/m3. This standard was set in 2002 through a public process that included peer-review by an independent panel of scientific experts appointed by the Office of the President of the University of California. The U.S. EPA’s proposed annual-average PM2.5 standard of 15 μg/m3 should be reconsidered in light of the recent epidemiologic and toxicologic studies which provide evidence of likely biologic mechanisms and suggest that the effects of PM2.5 may be twice as high as previously thought. Based on the PM2.5 concentrations observed in the available studies of long-term exposure, a level of 15 μg/m3 is clearly not health protective; many of the studies have mean concentrations that are very close to or below 15 μg/m3. For California alone, we estimate (using U.S. EPA-approved methodologies) that each μg/m3 above our State ambient air quality standard of 12 μg/m3 results in over 1000 premature deaths per year. While we strongly support U.S. EPA’s proposal to lower the existing 24-hour-average PM2.5 standard, we believe that the literature clearly points to a level at the lowest end of the range (30-35 μg/m3) recommended by the Clean Air Scientific Advisory Committee (CASAC).
We are also concerned about the proposed short-term coarse particle standard and lack of an annual-average coarse particle standard. While the scientific evidence up to 2002, on which the proposed standard is based, provided little data on coarse particles, we point out that a number of more recent studies that have not been considered in the standard review clearly point to important adverse health effects related to coarse particle exposure. We do not agree that the available evidence supports the conclusion that there are few or no adverse health effects associated with coarse particles originating in rural areas or areas dominated by crustal material. On the contrary, the available literature suggests that both short- and long-term exposures to coarse particles are associated with adverse health effects, including premature death. These findings are supported by both epidemiologic and toxicologic studies. We are concerned that by relying on only a subset of the available literature on coarse particles, U.S. EPA has proposed a standard that is not based on the most recent science and fails to adequately protect public health. Given that strong new evidence for adverse health effects related to coarse PM is now available, it is crucial that this new evidence be incorporated into the standard setting process, and the proposed coarse particle standard be reconsidered. The public should not have to wait until the next PM standards review to be afforded adequate protection from known adverse effects of coarse PM exposure because of an arbitrary publication cut-off date.
Historically, PM has been regulated on a mass basis, without regard for its specific components because considerable evidence points to adverse health effects attributable to particles in both the PM2.5 and PM10 size ranges. In addition, since there is insufficient evidence to differentiate the effects of specific subspecies in either size fraction, we believe this long-standing practice should be continued until there is evidence suggesting another regulatory approach is appropriate.
We are also concerned by the proposal to limit the coarse particle standard to urban areas. As a fundamental public health principle, residents in rural areas should be provided the same level of protection as those living in more populous urban areas. We disagree that the scientific literature leads to the conclusion that only urban coarse particles have toxic properties, and urge you to reconsider this proposal. If U.S. EPA differentiates between urban and rural coarse PM, either in establishing or implementing the coarse standard, large rural areas of California, where a significant fraction of the State’s population resides, would be exempt from federal requirements to reduce coarse PM levels, even though their monitored values could greatly exceed the proposed standard. This would result in differential levels of public health protection based solely on place of residence.
Equally concerning is the proposal to limit coarse particle monitoring to only urban areas. Since coarse particle monitoring in rural areas provides the data used for public health advisories to limit exposure on high particle pollution days, this limitation eliminates essential health advisories in rural areas of California. People living in 22 northern California counties would be excluded from coarse particle monitoring requirements. In addition, the loss of this data would limit the ability of scientists to conduct future health studies on the effects of coarse particles from rural sources.
You will find our detailed comments in Attachments A and B to this letter. We are pleased to continue our participation in the PM standards review process, and appreciate the opportunity to comment on the recommended standards. If you need additional information please contact Richard Bode, Chief of ARB Health and Exposure Assessment Branch at (916) 323-8413 or rbode@arb. or contact Dr. Bart Ostro, Chief of OEHHA Air Pollution Epidemiology Section, at (510) 622-3157 or bostro@oehha..
Sincerely,
/s/ /s/
Catherine Witherspoon Joan Denton, Ph.D., Director
Executive Officer Office of Environmental Health Hazard Assessment
Air Resources Board
Attachment
cc: Richard Bode, Chief
Health and Exposure Assessment Branch
Air Resources Board
Barto Ostro, Ph.D., Chief
Air Pollution Epidemiology Section
Office of Environmental Health Hazard Assessment
Attachment A
Comments on the U. S. EPA Proposed Ambient Air Quality Standards for Particulate Matter
Office of Environmental Health Hazard Assessment
and
California Air Resources Board
Health Basis of the Proposed Standards
The December 2005 U.S. EPA proposal for the Particulate Matter National Ambient Air Quality Standards (NAAQS) would not be protective of public health with an adequate margin of safety, as required under the federal Clean Air Act. Based on an objective review of the available science, it is clear that the current proposal fails to provide the adequate protection of public health from exposure to both fine and coarse particles. A careful review of the science was conducted over a period of several years by the Clean Air Science Advisory Committee (CASAC) in an open, public forum. The U.S. EPA proposal is not in accord with the CASAC review, and their interpretation and conclusions regarding the existing science. Many of the U.S.EPA recommendations are based on incorrect interpretation of the evidence, and downplay the strength of available evidence on the health effects of both fine and coarse PM. In particular, many of the statements in the Federal Register Notice (FRN): (1) overstate the uncertainty in the association between long-term exposure to PM2.5 and mortality; (2) misinterpret the evidence relating coarse particles to adverse health, or are not based on the latest science. In addition, many factors cited (e.g., exposure misclassification) would make it more difficult to find an effect, not less as implied in the preamble. Many of the arguments are neither compelling nor scientifically accurate in arguing against an effect that has been demonstrated in a large number of studies.
The U.S. EPA proposes to set the annual average PM2.5 standard of 15 μg/m3, a standard that would fail to provide an adequate margin of safety. It is important that U.S. EPA carefully consider the latest evidence on the effects of air pollution on health. Many new studies published since 2004 support the association between long term exposure to PM2.5 and mortality, including studies on animals and humans that now provide stronger evidence for mechanisms and larger effect estimates. As indicated below, when the exposure assessment is more accurate relative to the original examination of the American Cancer Society cohort, the risk estimates are more than twice as high. In other words, the estimated impacts of a standard that is too high or takes too long to attain, are even larger than those first estimated by USEPA, which are already quite significant. These mortality effects are demonstrated at current ambient concentrations, and many of the exposures in these studies are below 15 μg/ m3. Therefore, this proposed annual average standard provides no margin of safety, as required by the Clean Air Act, and is insufficient for protecting public health.
EPA must also consider the full body of evidence regarding coarse particles. The proposed short-term standard, 70 μg/m3, is completely inadequate given the available evidence of health effects of coarse particulate matter. Recent studies, both epidemiological and toxicological, indicate that coarse particles are toxic to humans (in some studies more so than fine particles) at levels that are much lower than those currently being proposed for air quality standards. As such, these levels are not protective in urban areas. In addition, public health protection to residents of small urban and of rural areas would be insufficient at this proposed standard concentration. There is no evidence that there is a safe level of exposure for these larger particles. Finally, there is no scientific basis for exempting particulate matter generated by mining or agricultural sources from regulation.
Our detailed comments are provided below.
New Studies on Long-Term Exposure to Fine Particles
In the FRN, EPA has failed to provide adequate weight to the independent reanalysis of the original long-term studies using data from the American Cancer Society (ACS) and Harvard Six-Cities cohorts (Dockery et al., 1993; Pope et al., 1995). This intensive reanalysis, under the auspices of the Health Effects Institute (HEI) reported that: (1) the original data were of high quality; (2) the original results could be fully replicated; and (3) after an exhaustive set of sensitivity analyses, the results were robust to alternative model specifications (Krewski et al. 2000; Krewski et al. 2004). This effort set a precedent for the intensity, completeness and exactitude in reanalyzing a data set. Rather than cite these results and their interpretation (as reported in the EPA Staff Paper and by CASAC), the FRN chose to focus on a few anomalous results, which are likely to occur when any dataset undergoes the exhaustive number of reanalyses, as were conducted in this case.
Since this careful reanalysis was conducted, several other studies have been published which suggest an urgent need to lower the standard. For example, the long-term effects of PM2.5 were studied in the Los Angeles basin using a subset of 23,000 subjects from the ACS study (Jarrett et al., 2005). This study is important since it developed far superior measures of exposure relative to the original analysis of the ACS. Exposures were interpolated to 267 residential zip-code centroids. In addition, there were fewer potential confounders since no inter-city comparisons were made as in the full ACS study. Additional controls were added for potential confounding from neighborhood-level effects. The authors report effects on all-cause and cardiopulmonary mortality that are almost 2.5 times larger than those reported from the full ACS study.
In an analysis of the full ACS national sample, disaggregated by separate cardiovascular diseases, Pope et al. (2004) reported significant associations between long-term exposure to PM2.5 (mean 17 μg/m3) and mortality from heart failure, cardiac arrest, dysrhythmias, and ischemic heart disease. Stronger associations between PM exposure and cardiovascular effects were found using only the most recent two years of PM2.5 data, corresponding to a lower mean concentration (14 μg/m3) (Pope et al., 2004). This data set included roughly three times the number of deaths and twice the follow-up time, relative to the original analysis of the ACS cohort. In addition, the analysis included specific tests for the influence of regional differences and spatial autocorrelation, which did not alter the general results.
In a recent reanalysis of the Harvard Six-Cities cohort, Laden et al. (2006) examined an additional eight years of data on mortality and PM2.5. As in the original analysis (Dockery et al. 1993), associations were observed for all-cause, cardiovascular, and lung cancer mortality. However, mean concentrations of PM2.5 were much lower in the analysis that used the second period of exposure (mean = 14.8 μg/m3). In addition, short-term (one or two years) reductions in PM2.5 were associated with reduced mortality risks, indicating that the effects of air pollution are reversible in a relatively short period of time by reducing PM. Again, the relative risks estimated from this study are 2.5 times that of the ACS study, but consistent with the original findings using the Six-Cities cohort.
In another recent analysis, which involved the Adventist Health Study of Smog (AHSMOG) data set with a cohort of roughly 6,500 non-smokers in California, long-term exposure to PM2.5 was associated with fatal coronary heart disease in women (Chen et al. 2005). Long-term exposure to PM2.5 was also examined using data from the Women’s Health Initiative Observational Study, a cohort of 66,000 postmenopausal women without prior cardiovascular disease (Miller et al. 2004). This study also utilized exposure metrics that were more accurate than those used in the original ACS (residential zip code centroids). The authors reported associations between long-term exposure to PM2.5 (mean 13.5 μg/m3) and both fatal and non-fatal cardiovascular events. After adjustment for individual-level risk factors, the authors calculated a 14% risk (95% CI, 3%-26%) in non-fatal cardiovascular events and a 32% (95% CI, 1%-73%) increase in fatal cardiovascular events.
These long-term studies of mortality were all conducted at ambient concentrations of PM2.5 to which people are currently exposed. The air quality data in these studies spanned the range of 12 to 15 μg/m3, with mean concentrations between 14 and 15 μg/m3. These findings on mortality are now supported by other studies that provide mechanistic evidence for the association. For example, Kunzli et al. (2005) found an association between long-term PM2.5 exposure and increased carotid intima-media thickness, a measure of subclinical atherosclerosis. In addition, using data from the Third National Health and Nutrition Examination Survey (NHANES III), Schwartz (2001) reported an association between long-term exposure to PM10 and several markers of inflammation and cardiovascular risk including fibrinogen levels and counts of platelets and white blood cells. In a toxicological study, Sun et al. (2005) demonstrated that hyperlipidemic mice chronically exposed to PM2.5 had higher rates of vascular inflammation and arteriosclerosis. These latter studies provide important support for the plausibility of an association between mortality and long-term exposure to PM2.5.
Other effects of long-term exposure have been reported by Woodruff et al (2006) and Gauderman et al. (2004). Woodruff (2006) examined the effect of exposure to PM2.5 over several months and post-neonatal death in infants born in California in 1999 and 2000 whose mothers lived within five miles of a PM2.5 monitor at the time of giving birth. A 10 μg/m3 increase in PM2.5 was associated with an almost two-fold increase in the risk of post neonatal mortality due to respiratory causes. Gauderman et al. (2004) used data from the Children’s Health Study, a prospective cohort of schoolchildren in the Los Angeles basin. In this study, long-term exposure to PM2.5 was associated with reductions in lung function growth over an eight-year period. In addition, exposure to PM2.5 and covarying combustion-related pollutants was associated with a permanent loss in lung function, based on a significant number of 18-year-olds with FEV1 below 80 percent of predicted values. These studies lend support to the mortality studies described above by indicating a coherence of effects related to long-term exposure to PM2.5. Finally, among studies of short-term exposure, Ostro et al. (2006) reported associations between PM2.5 and daily mortality in nine California counties. This study, along with an earlier study of six cities conducted by Schwartz (2003), indicate that by lowering the annual average of PM2.5, additional benefits would accrue from reductions in the daily average, as well.
In summary, the scientific literature clearly demonstrates that long-term exposure to PM2.5 (measured as several months to several years) is associated with all-cause and cardiovascular mortality in several diverse cohorts. Some of these studies report mean PM2.5 concentrations of 14 to 15 μg/m3 and all of the studies include significant data below 15 μg/m3. The effect estimates are significantly larger (almost twice as large as the original ACS results) when exposure misclassification is reduced. This indicates that the risk estimates for mortality may be twice as high as those estimated in the Staff Paper. In addition, these studies of mortality are now supported by several studies that demonstrate plausible biological mechanisms. Effects of long-term exposure have been reported for cardiovascular inflammation and atherosclerotic plaque development, arteriosclerosis and lung function. Additional studies have demonstrated associations between PM2.5 and infant morality.
Therefore, it is imperative for EPA to incorporate these studies in their consideration of the annual average standard for a PM2.5. The literature clearly supports a lower annual standard than proposed in the FRN, and we urge that the annual PM2.5 standard be set at 12 μg/m3. In consideration of the far-reaching consequences of this standard-setting process, we would like to stress the importance of establishing a PM2.5 standard that is protective of public health with an adequate margin of safety.
An annual PM2.5 standard of 12 μg/m3 is consistent with the recent review of the PM standards in California. In a recent review of the state particulate standard, California determined that an annual PM2.5 standard of 12 μg/m3 was needed to adequately protect public health. This standard was established following a process that included public comment and peer review by an independent board of scientists (the Air Quality Advisory Committee or AQAC) appointed by the University of California, Office of the President.
Effects of Coarse Particles
The FRN has reported that there are too few studies and too much uncertainty to propose a reasonably protective standard for coarse particles (PM10-PM2.5). As a result, a 24-hour average standard of 70 μg/m3 was proposed. This standard is insufficiently protective in light of many studies reported in the last few years that have demonstrated significant toxicity of coarse particles.
In our recent review of the California ambient air quality standards for PM, we retained the annual average standard for PM10 but lowered it from 30 to 20 μg/m3. The PM10 metric encompasses both fine and coarse particles. Our concern for controlling the coarse fraction was based largely on a review of studies similar to those reviewed in the Criteria Document that demonstrated increased risks of mortality and morbidity. Our own evaluation of the data, as well as the robustness of the PM10 literature, led us to retain the PM10 standard rather than develop a separate coarse particle standard.
As reviewed in the Criteria Document and summarized in the Staff Paper, there are several studies that attribute adverse health effects to coarse particle exposure. For example, Burnett et al. (1997) reported an association between coarse particles (mean = 11.5 μg/m3, 99th percentile = 36 μg/m3) and both cardiovascular and respiratory hospitalizations during the summer in Toronto, Canada. Castillejos et al. (2000) found an association between daily coarse particle exposures (mean = 17 μg/m3, maximum = 55 μg/m3) and mortality in southwestern Mexico City. The coarse fraction was not correlated with the fine fraction in this study. Associations have been reported between coarse particles and mortality in Steubenville (mean = 16 μg/m3, 99th percentile = 61 μg/m3; Schwartz et al., 2003) and hospitalization for asthma in Seattle (mean = 16 μg/m3, 99th percentile = 39 μg/m3; Sheppard, 2003). Higher concentrations of coarse particles (mean ~ 30 μg/m3) were also associated with mortality (Ostro et al., 2003; Mar et al., 2003). In Philadelphia and the surrounding metropolitan area, Lipfert et al. (2000) found stronger associations for fine particles than coarse particles, but the effects were of similar magnitude for the two measures. For respiratory mortality, the effect size was actually greater for coarse particles (mean = 6.9 μg/m3, 99th percentile = 19.3 μg/m3).
Among recent studies, Villeneuve et al. (2003) reported associations between coarse particles, but not fine particles and cardiovascular mortality in Vancouver. In another Canadian study, Lin et al. (2002) used both bidirectional case-crossover and time-series analyses to examine the effects of coarse particles on asthma hospitalization among children. Both techniques indicated that coarse particles, but not fine particles or any of the gaseous pollutants, were associated with asthma hospitalization and respiratory infections in both males and females. The effect estimate increased with the number of days included in the moving average (a measure not used very often in the studies of coarse particles). In the case-crossover analysis, an excess risk of almost 20 percent was reported for a 10 μg/m3 increase in the 6-day averages of PM10-2.5. Lin et al. (2005) conducted a bidirectional case-crossover study in Toronto examining hospitalization for respiratory infections in children. For both boys and girls, associations were reported for coarse, but not fine, particles.
Several other studies on morbidity have implicated coarse particles especially for respiratory effects on children, even when no association with fine particles was demonstrated. Coarse particles appear to be the predominant fraction associated with respiratory hospitalizations, asthma, and respiratory symptoms. For example, in Vancouver, Yang et al. (2004) found coarse particles to be significantly associated with first respiratory hospitalizations in children less than three years of age, while no significant associations were found for fine particles. Zhang et al. (2002) in a study in China reported significant associations for coarse particles (mean = 60 μg/m3, 99th percentile = 132 μg/m3) and bronchitis among schoolchildren in four Chinese cities. Furthermore, coarse particles were more strongly associated with all respiratory symptoms than were fine particles and all other pollutants in this study. In a study in Spokane, Mar et al. (2004) demonstrated a significant association between coarse particles and cough among children with asthma. Finally, a study conducted among children less than two years of age living in Toronto reported both fine particles and coarse particles to be significantly associated with respiratory hospital admissions (Burnett et al., 1997).
While the results of studies examining adults are more mixed, several studies do provide evidence of an effect of coarse particles. For example, Chen et al. (2004, 2005) examined the effects of PM on hospitalization for people over age 65 in Vancouver. Chen et al. (2004) reported an association between PM and COPD hospital admissions, and reported significant increases for both fine and coarse particles. In the second study, coarse particles were significantly associated with hospital readmission, while no significant effects were observed for fine particles. Coarse particles (mean = 13.3 μg/m3, 99th percentile = 40.2 μg/m3) were also found to be significantly associated with pneumonia (RR = 1.11, 95% CI: 1.01, 1.23 with 1-day lag) and ischemic heart disease (RR = 1.10, 95% CI: 1.03, 1.18 with 2-day lag) in a study conducted in Detroit (Lippmann et al. 2000; Ito 2003).
Several studies that measured only PM10 but were conducted in areas where coarse particles dominate the PM mixture provide support for respiratory and CVD effects. For example, Chen et al. (2000) reported an association between PM10 and COPD in Reno-Sparks, Nevada. Choudhury et al. (1997) reported associations between PM10 and emergency room visits for asthma, bronchitis and upper respiratory infections in the general population living in Anchorage (fall beta = 0.62; SE = 0.22), and Schwartz (1997) found an association between PM10 and cardiovascular hospitalizations in Tucson, Arizona.
Recent toxicological evidence also suggests that coarse particles play a different role from fine particles (US EPA 2004, 2005). Coarse particles specifically have a greater effect on epithelial cells and alveolar macrophages via oxidant formation and pro-inflammatory cytokines. These studies provide additional evidence of an independent, adverse effect of coarse particles.
The U.S. EPA has categorically exempted agricultural and mining sources of coarse PM from the proposed standard. Under the Clean Air Act, implementation is not to be considered in setting standards, so this exclusion can only be justified in the present process if there is no basis from a public health standpoint to control particulate matter emissions from these sources.
Agricultural, mining, and wind-blown dusts in both urban and rural areas can contain toxic elements originating from the earth’s crust. For example, in California’s Owen’s and Coachella Valleys, areas with high coarse PM levels, the soil contains high concentrations of arsenic, cadmium, and nickel. Crystalline silica, a common constituent of agricultural and mining dusts, is a human carcinogen, and can cause silicosis at relatively low levels in occupational settings. Moreover, microbiological products, such as endotoxin, which are ubiquitous in soil, are found preferentially in the coarse fraction. Endotoxin causes pulmonary inflammation and has been associated with increasing asthma severity (Reed et al. 2001). Thus, there is no reasonable scientific basis to exempt coarse PM originating from agricultural and mining activities from regulation under the proposed coarse particle standards.
In summary, short-term exposure to coarse particles has been associated with both mortality and morbidity. Of note, there are many recent studies, in which coarse, but not fine, particles appear to be the pollutant of concern. Coarse particles have been more consistently associated with respiratory symptoms, hospitalizations for respiratory infections and asthma in young children. In their review, Brunekreef and Forsberg (2005) concluded that exposure to coarse particles was generally a better predictor of asthma, COPD and/or respiratory admissions, although in some cases, fine particles and coarse particles were equally predictive of asthma effects. These reported effects occur at current ambient levels. Moreover, the results of these studies suggest effects of coarse particles at mean concentrations (using the annual mean of the daily averages) in the range of 11 to 30 μg/m3, with 98th percentile 24-hr concentrations between 30 and 53 μg/m3 (see Table 1). It is clear that for adequate protection of public health, the U.S. EPA standards for coarse particles must be more stringent than proposed.
Comments on the Review of the Ostro et al. (2000, 2003) studies in Coachella Valley
We concur with the FRN, that the “epidemiologic evidence suggests that short-term exposure to thoracic coarse particles is associated with effects on the cardiovascular system.” (p 2659) While the existing evidence is less than that for fine particles, given the severity of the outcome demonstrated in several studies, these studies should be given more serious attention.
We concur with the FRN statement (page 2669) that it is very likely that most of the population experienced concentrations that are “appreciably lower” than that measured at the Indio monitor. Therefore, the 98% percentile cited as an effect level is likely to be too high.
Page 2670, referring to the Ostro (2000) study in Coachella Valley and the Lippmann et al. (2000) study in Detroit, states that: “exposure measurement error is potentially quite large in these PM10-2.5 studies.” We concur that the current scientific consensus suggests that measurement of coarse particles will typically involve greater errors than that of fine particles. However, we reject the FRN implication that therefore these studies are not reliable. In fact, the larger measurement error, which is likely to be random, would make it more difficult to find an association with mortality. It is well accepted in the epidemiological literature that such measurement error will tend to obscure a relationship between an exposure and a given health outcome, assuming that such a relationship exists. Therefore, the measurement error argument cannot be used to nullify an effect that has been observed. If anything, it is likely that the real effects are likely to be larger than those that were estimated.
The FRN states (page 2672): “Ostro et al. (2003) used a one-pollutant model to estimate the association between PM10-2.5 on mortality using an effectively linear construct of PM10 (as observed in Indio, CA) to represent PM10-2.5 for the entire study area. By using such a construct of PM10, the estimated associations simply reflect a PM10 association (i.e., the construct does not provide additional information on the effect of PM10-2.5).” This statement is incorrect for the following reasons. First, a cubic function was used to estimate the empirical relation between PM10 and coarse particles. Second, the correlation between coarse particles and PM10 in Indio was 0.97. This says, very clearly, that almost all of the daily variation in PM10 is due to daily variation in coarse particles; the daily changes in PM2.5 contribute little to daily variation. An examination of the coefficients of variation of PM2.5 and PM10-2.5 shows a much greater variance associated with the mean for coarse compared to fine particles; the latter simply do not vary much in the study area. Thus, the construct does provide information on PM10-2.5. In Coachella Valley, PM10 and PM10-2.5 can be considered surrogates for each other. In fact, it would have been appropriate to have simply used PM10 as a surrogate for coarse particles.
The FRN continues (p 2672): “Moreover, roughly 75 percent of the cardiovascular mortality in this study occurred in or near Palm Springs, CA… Thus, the Ostro et al. (2003) study suggests a positive association between PM10 monitored in Indio and mortality in Palm Springs, but some view this study as offering little basis for attributing significant mortality association to PM10-2.5 as observed in either city.” It is not clear who (i.e., “some view”) is being referred to in the last sentence. This view was not expressed to the peer-reviewed scientific journal in which the article appeared, as no letters to the editor critical of this study have been published by the journal. Coarse concentrations in Indio and Palm Springs are highly correlated on a daily basis (r =0.61). In addition, as stated above, if the exposure is misclassified non-differentially, a lower effect estimate would result (i.e., bias towards the null hypothesis of no effect), rendering it more difficult to detect an association between daily mortality and PM. Finally, while a greater proportion of total deaths occurred in Palm Springs, it is quite possible that more (as a percent of total) pollution-related deaths could have occurred outside Palm Springs, where coarse particles are more of a concern, such as in Indio and the windy corridor of Coachella Valley. Peer reviewers for the original 2000 paper (and the follow-up paper, published in 2003 by HEI), the authors of the U.S. EPA Staff Paper, and CASAC all concurred with the authors’ conclusion that, in fact, there was a basis for attributing a significant mortality association to coarse particles. In addition, the low correlation between coarse and fine particles in Indio (r=0.28) made it easier to separate out the effects of these two pollutants.
Table 1: Summary of selected references examining CP (μg/m3) and health outcomes
|Reference |Health outcome/ |Mean |98th %a |99th %a |
| |study location | | | |
|Burnett, 1997 |Hospital admissions/Toronto |11.5 |29.5 |35.8 |
| | | | | |
| | | | | |
|Ito, 2003 |Respiratory and cardiovascular outcomes/ | | | |
| |Detroit |13.3 |36.2 |40.2 |
|Lipfert, 2000 |Mortality/Philadelphia |6.9 |18.3 |19.3 |
|Mar, 2003 |Mortality/Phoenix |33.2 |70.6 |75.4 |
| | | | | |
|Ostro, 2003 |Mortality/Coachella Valley |30.5 |106.8 |134.0 |
|Schwartz, 2003 |Mortality/Steubenville |16.1 |53.2 |61.4 |
|Sheppard, 2003 b |Asthma admissions/Seattle |16.2 |32.3 |38.7 |
|Zhang, 2002 c |Respiratory outcomes/ |60 |132 |132 |
| |4 Chinese cities (overall) | | | |
a 98th % and 99th % adapted from US EPA memorandum 1/28/05 Ross and Langstaff, except as indicated
b Not based on year-round data
c Obtained from correspondence with author
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Attachment B
Comments On
Proposed Changes to Title 40 of the
Code of Federal Regulations Parts 50, 53 and 58.
(Partial list of comments on Part 50)
California Air Resources Board
General Comments
The following are some overarching concerns regarding a few aspects of the proposed regulations that warrant being addressed comprehensively and not only as comments on isolated, specific sections of the proposed regulations.
PM10-2.5 Monitoring
We have strong concerns regarding the limitation of PM10-2.5 monitoring requirements to only large urban areas. Based on the proposed regulations, large areas of California, some with significant PM10-2.5 problems, would be excluded from the PM10-2.5 monitoring requirement. In fact, 22 counties in the northern part of the State with a combined population close to 2.3 million would not be required to monitor for PM10-2.5. Moreover, the regulations would lead to situations such as the exclusion of monitoring in the Hanford-Corcoran Metropolitan Statistical Area (MSA) which has the highest estimated PM10-2.5 design value in the San Joaquin Valley Air Basin because it does not contain an urbanized area with a population greater than 100,000. Additional examples are included in our comments below on 40CFR58 Subpart D Section 58.30. A comprehensive monitoring network, as well as nonattainment area boundaries that appropriately reflect the scope of the problem, will be essential in providing adequate public health protection and adequately characterizing population exposure throughout the State. PM10-2.5 monitoring that is approved for use in comparison to National Ambient Air Quality Standards needs to be allowed for all areas, irrespective of population.
State Flexibility in Network Design. We believe it is appropriate for the U.S. Environmental Protection Agency (U.S. EPA) to define minimum monitoring requirements and to require U.S. EPA approval for changes to this minimum network. However, it should be recognized that states will have many monitoring needs that go beyond those specified in the minimum requirements. California comprises a diverse range of topography, meteorology, emissions, and air quality. As a result, a diverse network of monitors is needed to characterize air quality problems. States should be provided with the flexibility and discretion to meet these broader network needs. The proposed regulations would require Regional Administrator approval for a state to add or discontinue most all monitors, even those not required to meet the federal requirements for numbers of monitors. This represents a greatly expanded approval role for the U.S. EPA than what is authorized in the existing regulations. This requirement will greatly hinder the flexibility of state and local agencies to respond to changing needs and resources. Moreover, while the U.S. EPA partially supports federally mandated air quality monitoring in California, it does not fully support these networks and even the present level of support is planned to be dramatically reduced. With shrinking levels of support, the U.S. EPA should have a lesser role in deciding matters of network design and operation rather than a greater one.
Funding for Existing and New Federal Mandates. Though not directly mentioned in the proposed regulatory changes, funding issues are implied with the addition of monitoring requirements for a new criteria pollutant, multi-pollutant sites, trace level monitoring, etc. The U.S. EPA should fully fund these new monitoring activities through the Section 103 funding mechanism as was used for the first few years of the PM2.5 monitoring implementation. State and local air quality monitoring agencies will be best enabled to implement new federal monitoring requirements with Section 103 funds rather than Section 105 funds. Only Section 103 funds are specifically earmarked for monitoring activities and they do not require a matching allocation from state legislatures. More funding will be required to meet federal requirements, not less.
Specific Comments
40CFR50 Appendix L Section 10.0: PM2.5 Measurement Procedure
The time limit for sample retrieval is proposed to be increased from 96 hours to 177 hours following the end of the sampling period. The reason given in the preamble for increasing the time limit was to reduce the filter retrieval burden (less labor), as advocated by some states and local agencies.
We believe it is inappropriate to increase the maximum allowable sample retrieval time. Increasing the retrieval time can significantly increase the loss of sample due to volatilization of particulate matter off the sample filter. In fact, we advocate a decrease in sample retrieval time requirements, especially for the National Core Network (NCore) sites. For the State and Local Air Monitoring Stations (SLAMS) monitors that are not NCore monitors, we request that more consideration be given to decreasing the retrieval time requirements, and, if those requirements are not decreased, that there be no increase in the maximum allowable retrieval times.
An NCore site, as a multi-pollutant monitoring site, would have an operator on site to ensure the proper functioning of the various instruments. With the frequent presence of an operator at a station, it is quite reasonable to accommodate a decrease in particulate matter sample retrieval time below the current 96 hours. Decreasing the retrieval time would help reduce volatilization of particulate matter off the sample filter, a loss known to happen when samples are kept at ambient conditions for a longer time than necessary.
40CFR50 Appendix O Section 1.0: Applicability and Definition
Paragraph 1.3 presents the possibility of having a filter-based federal equivalent method (FEM) for PM10c that is based on some minor changes to PM2.5 samplers.
The high volume size selective inlet (SSI) PM10 federal reference method (FRM) currently used by the State of California is a State method for PM10. In California, the high-volume SSI agrees to within five percent of the low volume PM10. In an ARB 2001/2002 Samplers Comparison Study, the SSI and PM10 Partisol samplers were found to agree to within two percent of each other (slope = 1.04, intercept = -2.18 ug/m3, r = 1.00, and n = 30). This is a better agreement than the criteria indicated for the Class III equivalency test. We recommend that the SSI be allowed to be equivalent to PM10c for PM10-2.5 measurement.
Also, it should be noted that operating two separate samplers (PM10c and PM2.5) for measuring PM10-2.5 poses several problems. Due to a limited platform space some existing monitoring sites may not be able to accommodate an additional sampler, and in some cases more than one additional sampler. Having two separate instruments also increases the uncertainty of the measurement.
40CFR53, Subpart C: Table C-4 to Subpart C - Test Specifications for PM10, PM2.5, and PM10-2.5 Candidate Equivalent Methods
Relaxing the limits of adequate comparability, as proposed in Table C-4 and illustrated in Figure C-2, would allow instruments that collect significantly different measurements to be considered equivalent for a comparison to the Standard. The regulation should specify method equivalence criteria that are stricter than those in the proposed regulation.
Also, Table C-4 provides a specification for correlation as one of the test specifications for candidate equivalent methods. In the current 40CFR58, the term “correlation” has created confusion in the past because it is not clear if it is defined as R (correlation coefficient) or R2 (coefficient of determination). We suggest specifying the term with the use of symbols.
40CFR58 Subpart B Section 58.10: Monitoring Network – Annual Monitoring Network Plan and Periodic Network Assessment
Paragraphs 58.10(a) and (b) specify requirements for an annual monitoring network plan. This annual network plan would take significantly more effort to develop than the plan required by the existing regulations. The required scope of the annual plan is quite extensive. We do not believe that an annual plan is necessary or that it will be very useful. The monitoring network does not change much in a year’s time, but confirming this every year would require significant coordination for a network of more than 700 monitors, as exists in California. In addition to confirming the status of dozens of parameters for each monitor and updating cost information for the network, a public comment period is required. The effort put into compiling the annual network plan will detract from more critical monitoring needs. The draft regulations should be modified to make this a biennial requirement.
As a second point regarding paragraph 58.10(a), the ARB supports having a process for public input on the air monitoring network in California. We provide a wealth of information about our network on our public webpages and invite comments from the public at any time. Although we support transparency of our monitoring plans, we prefer to leave to individual states the decisions on when and how to solicit public input in the planning process. We request that the regulations allow this flexibility.
Paragraphs 58.10(e) requires that states complete a comprehensive assessment of the monitoring network every five years. Substantial staff resources will be required to complete the assessments as proposed. We believe that other assessment methods are preferable. We encourage the U.S. EPA to consider alternatives to the resource-intensive process being proposed.
As relates to paragraph 58.10(f), requiring U.S. EPA review/approval for monitoring site changes as part of the annual network review is a reasonable approach in the case of sites used to meet minimum federal requirements. It recognizes the fact that emissions, population distributions, and resulting air quality can change, making site relocation necessary in order to maintain a representative network. It also recognizes that improvements in monitoring techniques can help in maintaining a relevant network. However, review/approval for all site changes can be burdensome to a state’s efforts to maintain a representative network. States should be allowed the flexibility to move/remove sites that are not designated as federally-required without the need for formal U.S. EPA review/approval.
Also the requirement in paragraph 58.10(f) conflicts with Section 58.30, paragraph (f) which states that U.S. EPA approval is not needed to discontinue a special purpose monitor (SPM). We believe that U.S. EPA approval should not be required.
40CFR58 Subpart B Section 58.12: Monitoring Network – Operating Schedules
Paragraph 58.12 (d)(1) requires 1-in-3 sampling for PM2.5 federal reference method (FRM) samplers, unless you can meet some fairly restrictive criteria. The proposed requirement can be unnecessary and overly expensive, especially for areas that include more than the minimum required number of PM2.5 sites. The 1-in-3 day sampling requirement should be limited to the high design value site in each CSA, where that design value exceeds 90 percent of any PM2.5 National Ambient Air Quality Standard (NAAQS), and to all sites in the non-attainment area with design values within 10 percent of such a high design value. When an area is nearing attainment, this alternative proposal is approximately equivalent to the draft requirement. When an area is far from attainment, it provides for a better determination of the design value and potentially saves a lot of money.
Paragraph 58.12 (d)(3) requires 1-in-3 day sampling for speciated PM2.5 sites that are part of the speciated trends network (STN). The California network includes seven STN sites. With the three years of monitoring that is required for area designation determinations, 1-in-6 day sampling for speciated PM2.5 would provide a sufficient understanding of the PM2.5 chemical speciation at the STN sites. The resources saved with 1-in-6 day sampling can be better utilized in areas that are non-attainment for PM2.5 to support additional PM2.5 speciation sites for improved characterization of spatial variability. We request that the draft requirement be changed to 1-in-6 day sampling.
Paragraph 58.12 (e) requires daily sampling for manual PM10-2.5 monitors that are not collocated with a continuous PM10-2.5 monitor. Daily sampling entails very high laboratory costs and operation and maintenance costs, and does not seem necessary. While deployment of a collocated continuous monitor reduces the required sampling frequency, no such monitor for PM10-2.5 has yet to be fully tested, let alone proven to work satisfactorily in routine field operation.
40CFR58 Subpart B Section 58.14: System Modification
The proposed regulations require state and local air quality monitoring agencies to seek approval from the Regional Administrator for any changes to their state and/or local air quality monitoring networks. This requirement will greatly hinder the flexibility of state and local agencies to respond to changing needs and resources. Moreover, while the U.S. EPA partially supports federally mandated air quality monitoring in California, it does not fully support these networks and even present support is planned to be dramatically reduced. With shrinking levels of support, the U.S. EPA should have a lesser role in deciding matters of network design and operation rather than a greater one.
40CFR58 Subpart B Section 58.16: Data Submittal
Paragraph 58.16 (a) requires submittal to the U.S. EPA’s air quality database of all data for most pollutants regardless of whether the data are from routine monitoring or from special study monitoring. This is a lot more data than are submitted currently and would be a burdensome requirement. Special study data may not be fully quality assured and may not be in a format that can be readily submitted to the U.S. EPA. The regulatory language should make this distinction and make the submittal of special study data optional. Also, this paragraph does not exclude data from special purpose monitors (SPM) that are not an FRM, federal equivalent method (FEM), or ARM, even though Section 58.20 (b) implicitly excludes such data.
40CFR58 Subpart C Section 58.20: Special Purpose Monitors (SPM)
This section proposes specific requirements on the use of SPM data for attainment purposes and the inclusion of SPM data in the federal air quality database. The regulations should specify that data that do not meet criteria for use for regulatory purposes be clearly flagged as such. Also, while allowing data collection for a fixed time period without non-attainment consequences would encourage rather than discourage monitoring in new, suspected high concentration areas, it may not be the best approach for protecting human health. If SPM monitoring indicates that the site may exceed a NAAQS for a pollutant and might do so to a greater extent than any other site in the area, then the regulations should specify that an attainment designation not be allowed for the area until attainment is demonstrated through monitoring at the SPM location. This approach will better assure that an area is truly in attainment before it is designated as attainment.
40CFR58 Subpart D Section 58.30: Special Considerations for Data Comparison to the NAAQS
The five step suitability test for comparability of the PM10-2.5 data to the PM10-2.5 NAAQS is overly prescriptive. In order to maximize resources, the existing PM2.5 sites should be considered as a high priority for PM10c monitor placement. The suitability test can interfere with this. In addition, the local air quality agencies should be given flexibility in deciding where to place PM10c monitors to best complement the existing network and to adequately protect public health by characterizing exposure in both urban and rural areas.
Based on the proposed regulation, large areas of California, some with significant PM10-2.5 problems, would be excluded from the PM10-2.5 monitoring requirement. For example, 22 counties in the northern part of the State with a combined population close to 2.3 million would not be required to monitor for PM10-2.5. Some of the areas in the eastern and southern part of the State would also be excluded from the monitoring requirement, even though their estimated design values greatly exceed the level of the proposed standard. For example, the Great Basin Valley, Mojave Desert, and Salton Sea Air Basins, each with an estimated design value significantly higher than the proposed standard, ranging from 90 µg/m3 to 230 µg/m3 based on 2002-2004 data, would not be required to monitor for PM10-2.5. In other areas, like the San Joaquin Valley Air Basin in central California, the proposal, which focuses on monitoring in urban areas, would create potentially multiple, discontinuous nonattainment areas within the region, instead of addressing the problem from an integrated basin-wide perspective. For example, the Hanford-Corcoran Metropolitan Statistical Area (MSA) with a population of about 130,000 and the highest estimated PM10-2.5 design value in the basin of 90 µg/m3 (based on 2002-2004 data) would not be required to monitor for PM10-2.5 because it does not contain an urbanized area with a population greater than 100,000. A comprehensive monitoring network, as well as nonattainment area boundaries that appropriately reflect the scope of the problem, will be essential in providing adequate public health protection and adequately characterizing population exposure throughout the State.
40CFR58, Appendix A: Quality Assurance Requirements for SLAMS, NCore, and PSD Air Monitoring.
3.2.1.1 "Except for certain CO analyzers described below, point analyzers must operate in their normal sampling mode during the QC check, and the test atmosphere must pass through all filters, scrubbers, conditioners and other components used during normal ambient sampling and as much of the ambient air inlet system as is practicable."
The word “as practicable” allows too much latitude if the point of the comment is to ensure thru the probe spans. We suggest the language specify a distance from the inlet, e.g., within 18 inches of the probe inlet, or perhaps at or above the first junction in the inlet line.
3.2.2.1 (a) "The evaluation is made by challenging the analyzer with audit gas standard of known concentration (effective concentration for open path analyzers) from at least three consecutive ranges that are applicable to the analyzer being evaluated."
Since the ambient levels measured at each station varies, how do auditors determine the three applicable audit ranges from the five ranges available?
40CFR58 Appendix A Section 3.2.3: Flow Rate Verification for Particulate Matter
For both manual and automated PM samplers, flow check and leak check data are as important for validating proper performance as bi-weekly precision checks are for ozone and the other gaseous criteria pollutants. As such, submittal of these data to the U.S. EPA’s air quality database should be required just as precision checks of gaseous criteria monitors are required. For some continuous PM technologies (e.g., beta attenuation method (BAM) monitors) leak checks are just as important as flow checks. The regulations should be modified to require the submittal of both these important quality control (QC) criteria.
40CFR58 Appendix A Section 3.2.5: Collocated Procedures for PM10-2.5 and PM2.5
The proposed regulations encourage a PM10-2.5 network composed mainly of FEM methods but the only collocated requirements are for a small percentage of FEMs to be collocated with FRMs. The proposed regulations should be modified to require a specific percentage of sites to collocate FEMs for the express purpose of assessing FEM-to-FEM precision. Current federal regulations allow periodic flow checks to be used to assess continuous PM10 precision but this is flawed as it only assesses the precision of the flow measurement/control rather than the mass-per-volume which is the key parameter of interest.
40CFR58 Appendix C Section 2.0: SLAMS Ambient Air Monitoring Stations
For purposes of showing attainment, the draft regulations allow the use of PM10 data in lieu of PM10-2.5 monitoring, if some specified conditions are met. Paragraph 2.2.2. requires that the PM10 data that are used in lieu of PM10-2.5 monitoring be based on a daily sampling frequency. Sampling for PM10 on a daily basis would entail much higher costs, as compared to less frequent sampling. Less frequent sampling should be sufficient, especially because PM10-2.5 is a subset of PM10, and use of PM10 data typically will include a significant margin of safety in overestimating the PM10-2.5.
Paragraph 2.4.1.1. contains requirements for the acceptable locations for testing of a candidate approved regional method (ARM) for continuous PM2.5. To avoid the possibility of creating a confounding mix of ARMs within a state, the regulations should be modified so that the U.S. EPA can only accept applications for ARM status from the controlling state agency and not from local agencies. Also, the testing is not required to occur at the design value site for an area. Such a requirement would help assure that the method will perform well at some of the most important sites in the area.
40CFR58 Appendix C Section 3.0: NCore Ambient Air Monitoring Stations.
U.S. EPA should provide Standard Operating Procedures for analyzers used in trace-level CO, SO2, and NO/NOY monitoring to maintain consistent operating methodology at sites nationwide and simplify deployment of NCore monitoring sites. Also, since most state and local agencies will likely have no more than one NCore site within their jurisdiction, it is not efficient for each agency to develop Operation Procedures independently.
40CFR58 Appendix D Section 2(c): General Monitoring Requirements
The proposed regulations state that data from NCore sites will be used for long-term trends determinations, but do not explicitly state this for the large number of SLAMS sites that are not NCore sites. Given the diversity of California’s air quality problem, a handful of NCore monitors will not be able to adequately characterize conditions statewide. The limited number of NCore sites will not adequately monitor trends, and they will not tend to be the sites at which people are exposed to the highest levels of all of the individual pollutants. Data from non-NCore sites can be important indicators of trends, and the regulations should clearly state this.
The proposed regulations encourage the selection of “long term” sites for NCore monitoring. “Long term” is vague. Exactly what is desired? It is unlikely that state and local agencies will buy property for air monitoring purposes, but clear and specific regulations could be used to justify long term leases.
40CFR58 Appendix D Sections 4.2-4.5: Pollutant-Specific Design Criteria for SLAMS Sites – Carbon Monoxide Design Criteria; Nitrogen Dioxide Design Criteria; Sulfur Dioxide Design Criteria; Lead Design Criteria
With U.S. EPA approval, states could discontinue monitoring for these pollutants at non-NCore sites in areas with concentrations well below the NAAQS. No non-NCore site for such a pollutant might remain in an area if the entire area is below the standard. If subsequently concentration levels increase above a NAAQS for that pollutant, nothing in the regulations would require monitoring. The regulations should include requirements for monitoring at an expected high site if at any time there is reason to believe an area may be close to exceeding a relevant NAAQS. The proposed language does not assure this.
40CFR58 Appendix D Section 4.8: Pollutant-Specific Design Criteria for SLAMS Sites – Coarse Particulate Matter (PM10-2.5) Design Criteria
Paragraph 4.8.1 (b) addresses the minimum requirements for PM10-2.5 monitoring and refers to Table D-5, which quantifies those requirements. While we oppose the limitation of the broader PM10-2.5 monitoring network to only urban areas with a population greater than 100,000, we believe the requirements for the number of minimum monitors should be structured similar to the requirements for PM2.5 and ozone. In general, the minimum numbers of required PM10-2.5 monitors are more than twice the numbers of required PM2.5 monitors, based on areas of similar population with design values that are a similar percent of the respective NAAQS. Furthermore, unlike the requirements for ozone and PM2.5 which are based on populations in a metropolitan statistical area (MSA) or CSA, Table D-5 requirements are based only on MSA populations. Because a CSA is made up of two or more MSAs, this factor alone ends up requiring many more PM10-2.5 monitoring sites. In addition, based on paragraph 58.12 (e), some manual PM10-2.5 samplers may be required to operate on a daily basis. Taken together, these requirements will not necessarily result in the best use of limited monitoring resources. We recommend that the table be structured much more like Table D-4 for PM2.5, in terms of the required minimum numbers of monitors, the design value cut-points as percents of the NAAQS, and the inclusion of CSA as a basis for population.
Paragraph 4.8.3., PM10-2.5 Chemical Speciation Site Requirements, requires one speciation monitoring site in each MSA with population greater than 500,000 that also has an estimated PM10-2.5 design value greater than 80 percent of the NAAQS. This requirement has the potential to result in a lot of expensive laboratory analyses for non-attainment areas comprised of more than one MSA in which one MSA has significantly worse PM10-2.5 air quality. We recommend that the requirement be based on MSA or CSA, that an additional, higher population threshold be included, and that an additional speciation site be required for this highest level of population if the PM10-2.5 design value is greater than 120 percent of a PM10-2.5 NAAQS. This could be included in the regulations as a table similar to the tables listing the minimum numbers of required monitors for ozone, PM2.5, and PM10-2.5.
40CFR58 Appendix E Section 6: Probe and Monitoring Path Siting Criteria for Ambient Air Quality Monitoring – Spacing from Roadways
This section proposes increasing the minimum distance from roadways for ozone monitors to reduce the impacts of NOX scavenging. While this is an excellent idea, changes in monitoring location to accommodate revised distance from roadway requirements could compromise long-term monitoring records at individual sites. If a monitor is relocated, parallel monitoring should be conducted to document changes in concentration resulting from monitor relocation.
-----------------------
Office of Environmental Health Hazard Assessment
Joan E. Denton, Ph.D.
Director
State of California
Governor Arnold Schwarzenegger
Air Resources Board
Robert F. Sawyer, Ph.D.
Chair
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