Effects of Tobacco Use on the Vital Lung Capacity of ...



Effects of Tobacco Use on the Vital Lung Capacity of Healthy Male Students

Laura Powell, and Nicole Mills

Department of Biological Science

Saddleback College

Mission Viejo, CA 92692

Abstract

Smoking tobacco, while a continuing health concern, remains prevalent in society today. In this study, the exhaled vital capacities of healthy smoking and nonsmoking male college students were measured using a bell spirometer. All data was collected and a one-tail unpaired t-test assuming unequal variances was performed using Microsoft Excel. The average vital capacity of nonsmoking males was found to be 4.46 L + 0.22 (+SE, N=10). Similar to the previous group, the average vital capacity of smoking males was found to be 4.07 L + 0.18 (+ SE, N=10). The vital capacities of smoking males were not found to be significantly lower than the vital capacities of nonsmoking males. Although the results did not show a significant difference in lung capacity, this does not suggest that smoking males have the equivalent lung function of nonsmoking males. It simply shows that smoking males have the capability to uptake the same volume of air as nonsmoking males.

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Introduction

Tobacco use in the population is a continuing health concern. Chemicals are released by the burning of tobacco. When smoke is inhaled airway resistance increases. Carbon monoxide, one of many harmful byproducts of tobacco smoke, binds to the red blood cells’ hemoglobin faster and stronger than oxygen does. The result of the competition between the excess carbon monoxide and oxygen is a decrease in the diffusion capacity for oxygen (Tzani et al. (2008). Tobacco use can also cause asymmetry in lung units which results in increased alveolar volumes and pulmonary obstruction (Prediletto et al, 2007). Evidence has also been found of a relationship between tobacco use and the forced expiratory volume in one second/vital capacity of the lungs (Taylor et al. 2002). Rizzi et al. (2004) found that smokers had significantly poorer lung function, even in the absence of any clinical symptoms. Based off of the previous research, there is suspicion that some of the adverse tobacco affects may be overlooked in seemingly healthy adult males.

The purpose of this project is to determine the percent difference in the vital lung capacity (VC) of healthy smoking and nonsmoking males at rest. Along with vital capacities, the tidal volumes, expiratory reserve volumes, and inspiratory reserve volumes will be collected and compared. Because of the negative impact of smoking on lung function, our hypothesis is that smoking males will have a lower average lung vital capacity than nonsmoking males. It is expected that there will be a direct relationship between smoking and decreased lung function resulting in lower lung vital capacities.

Materials and Methods

Ten smoking and ten nonsmoking male students attending Saddleback College in Mission Viejo, CA participated in this study. All 20 subjects were between the ages of 18 and 25 and in good health with no history of asthma, lung or heart diseases.

The height and weight of all subjects as well as the daily smoking habits of the smoking male subjects were recorded prior to conducting the tests. A bell spirometer, provided by the Biological Department at Saddleback College, was used to record (in liters) the vital lung capacity (VC), tidal volume (TV), and expiratory reserve volume (ERV) of both groups. After the necessary measurements were recorded, the inspiratory reserve volume (IRV) was calculated using the following formula:

IRV = VC - (TV + ERV)

The measurements of the TV (volume of air exhaled when taking a normal and unforced breath), ERV (additional air that can be forced out after exhaling a normal and unforced breath), and VC (maximum volume of air completely exhaled after taking a complete and deep breath in) recorded by having each subject exhale into the cardboard mouthpiece.

To deflect possible measurement errors, all subjects were asked to firmly place their lips around the cardboard mouthpiece to minimize the amount of air escaping through gaps between the subjects’ mouths and cardboard mouthpieces. If a subject’s TV was measured as being greater than or equal to 1.0 L or the subject appeared to have been forcing his breath, the measurement was retaken.

Using Microsoft Excel, a one-tailed t-test assuming unequal variances was performed to compare the average VCs for each group.

Results

The average vital capacity for nonsmoking males was 4.46 L + 0.22 (+SE, N=10). The average vital capacity for smoking males was 4.07 L + 0.18 (+ SE, N=10) A one-tailed t-test revealed that the average lung vital capacity for nonsmoking males was not significantly higher than the average lung vital capacity for smoking males.(p=0.091) The supporting data is shown in Figure One.

Table 1. A comparison between the mean TV, ERV, and IRVs of smoking and nonsmoking males. No significant differences were observed in this comparison.

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Figure 1. Compared mean vital capacity values of nonsmoking and smoking males. There was no significant difference between the two groups.

The mean TV, ERV, and IRV of both groups are shown in Table One. Also shown in Table One are the results for the one-tailed t-test for each group.

Discussion

The results show that although there is a difference between the vital capacities of nonsmoking and smoking males, the difference did not reach the level of significance. There was also no significant difference in TV, ERV, or IRV of smoking males when compared to nonsmoking males. There were some factors that could have been better addressed in this experiment. Because of the equipment used in this experiment, the collected data depended upon each subject fully understanding the action they were being asked to perform. If a subject misinterpreted the type of exhalation desired, then the results may have been negatively affected. Also, increased selectivity of subjects in this experiment would have been beneficial. Having subject groups that were more unified would have cut down the impact of outside factors. However, given the time period in which this experiment was performed, strict selectivity may be an unrealistic feat. In a previous analysis of 7882 subjects, passive smokers were observed over the course of a year and found to have lower lung function than those who were not exposed, although the difference was only marginally significant (Janson et. al. 2001). This suggests that a larger sample size and longer observation time may increase the likelihood of finding a statistical difference.

Although the results did not show a significant difference in lung capacity, this does not suggest that smoking males have the equivalent lung function of nonsmoking males. It simply shows that smoking males have the capability to uptake the same volume of air as nonsmoking males. Smoking can affect oxygen kinetics and uptake at different levels. (Tzani et al., 2008) Even though the smoking males in this experiment could hold the same amount of air as nonsmoking males, the project did not continue on to find the efficiency of oxygen uptake.

References

Janson, C., Chinn, S., Harvis, D., Zock, J., and et al. Effect of passive smoking on respiratory symptoms, bronchial responsiveness, lung function, and total serum IgE in the European Community Respiratory Health Survey: A cross-sectional study.  The Lancet  358.9299 (2001): 2103-2109. Retrieved November4,2009.

Prediletto, R., Fornai, E., Catapano,G., Carli,C. (2007). Assessment of the alveolar volume when sampling exhaled gas at different expired volumes in the single breath diffusion test. BMC Pulmonary Medicine 2007, 7:18. Retrieved September 4, 2009, from .

Rizzi, M., Sergi, M., Andreoli, A., Pecis, M., Bruschi, C., & Fanfulla, F. (2004). Environmental tobacco smoke may induce early lung damage in healthy male adolescents. CHEST, 125(4), 1387-1393. Retrieved September 5, 2009, from CINAHL Plus with Full Text database.

Taylor, D., Fergusson, D., Milne, B., Horwood, L., Moffitt, T., Sears, M., et al. (2002, August). A longitudinal study of the effects of tobacco and cannabis exposure on lung function in young adults. Addiction, 97(8), 1055-1061. Retrieved September 5, 2009, from CINAHL Plus with Full Text database.

Tzani, P., Aiello, M., Colella, M., Verduri, A., Marangio, E., Olivieri, D., and Chetta, A. (2008). Lung Diffusion Capacity Can Predict Maximal Exercise in Apparently Healthy Heavy Smokers. Journal of Sports Science and Medicine (2008) 7, 229 – 234. Retrieved September 4, 2009, from .

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