5 - Nucleus



11. PERSONAL PROTECTION AND DOSE REDUCTION MEASURES

11.1 Introduction

11.1 11.2 Protective ware

11.2 11.3 Respiratory protection

11.3 11.4 Decorporation

11.4 11.5 Iodine thyroid blocking

11.5 11.6 Personal shielding

11.6 11.7 Personal hygiene

11.611.7.1 Food and drinking water monitoring for workers

11.67.2 Sanitary aspects

11.67.3 Prevention of heat stroke

11.67.4 Mental health

11. PERSONAL PROTECTION

11.1 Introduction

Radiation could not be the main dangerous factor required protection. More attention has to be paid to other conventional danger encountered in the working environment. In this chapter, however, only radiation hazard is considered for protection.

11.1 2 Protective ware

Protective ware is more frequently used to prevent radioactive substances either making direct contact with or entering the body and delivering internal exposures. The use of protective ware is especially important in for the protection of emergency workers involved in emergency operationssince there is large possibility of contamination that results in external exposure as well as internal exposure.

Several kind of protective wares such as coveralls or anoraks are used in workplace at nuclear facility or research facilitiesy’s workplace to protect against radioactive contamination of the body. There are mMany kinds of products are available, and their quality vary varies in each aspect such as durability, in their resistance to chemicals, flames and heat, in comfort, and in cost, and so on. And these protective wares are still available in emergency operations.

Protective wares are generally classified in characteristic as follows.

Permeable suits are most more comfortable for long term work. However, until recently permeable suits were woven garments type and they were easy to retain contamination. RecentlyNow, non-woven permeable suits are commercially available.

For more severe conditions, non-woven fabrics or impermeable suits made ofcoated with rubber or plastic coated are available. They also tend to cause and retain perspiration.

Fully impermeable, pressurized suits provide the highest level of protection. But they induce and not absorb perspiration.

In some type protective wares, it is appropriate dispose after one-time uses. Disposability might be considered in some cases. Disposing used suits could result in decontamination of the body and prevention of transfer or re-suspension of contamination. It can be decontaminated by removing suits and avoid transferring or re-suspending contamination. Protective ware which is high-performance with a little quantity is effective from an aspect of the waste reduction.

Very large numbers of workers are involved in emergency operations at a time, so it is necessary to regularly provide an ample number of various protective wares in at appropriate locations. And in the emergency, securing of transportation and procurement route of protective wares are important.

Workplace monitoring date data, type of requested work and the performance information of the protective ware are necessary before selectingfor the best selection of appropriate protective ware. Workplace monitoring for radiation and contamination may determine provide information regarding the radionuclide(s) present, the type of potential exposure(s) and magnitude of possible doses, the physical form of the radiation source(s), and the nature and concentration(s) of any contamination. The radiological risks need to be considered together with other hazards to appreciate the difficulties of accomplishing the work wearing protective ware.

Performance information of the protective ware, such as materials, permeability, water proof property of the product are usually given in the catalog. And manufacturers also typically supply information relating to the care and use usage of the product.

A list of performance levels helps in choosingus to choose the most appropriate suit for the intended work.

The general guidance for choosing protective suits is described as in the tTable 13 in the Practical Radiation Technical Manual – Personal protective Equipment (IAEA-PRTM-5 IAEA,2004)[2101]

For the selection of appropriate protective ware it is necessary to consider radiological risks together with other risks that are increased by wearing the protective ware. In some case iIt is also effective wearing to wear two kinds of types of wares, such as wearing waterproof suit on a permeable suit for the laboring work get wet.

11.2 3 Respiratory protection

There are two categories of respiratory Respiratory protective equipment is divided into two categories andwith several subdivisions in each category.

(i) Respirators

They can pPurify the air by filtering out particulate materials such as dust or low concentrations of gas or vapor. The most common types are;

(a) Filtering face piece respirators;

(b) Half face mask respirators;

(c) Full face mask respirators;

(d) Powered respirators

(ii) Breathing equipment

They can pProvides clean air or oxygen from an independent, and uncontaminated source. The most common types are;

(a) Supplied-air respirators

(b) Self-contained breathing apparatus

At theBefore using of a respiratory protective equipment, it must be confirmed their its performances. Two main protection factors shown below are used to check the performance.

+ Nominal protection factor (NPF)

-- The expected ratio of the contaminant concentration of contaminant in the ambient atmosphere to the concentrationthat of the contaminant inside the respiratory protective equipment.

+ Assigned protection factor (APF)

-- APF is defined by national standards and referred to inbased on national regulations. So that APF may vary from country to country.

The effectiveness efficiency of a respirator in to minimizing minimize inward leakage depends on two parameters.

+ The integrityfitness to of the face seal

+ The filtration capabilityfiltering efficiency of the selected filter medium or canister

Changing either or both of these factors can have a significant effect on the degree of protection actually achieved.

Workplace monitoring date data, type of requested work and the performance information of the respiratory protective equipment are necessary for the best selection of appropriate before selecting respiratory protective equipment.

The physical and chemical forms and concentration of contamination contaminants in the workplace would will determine therestrict the choice to certain types of respirator or breathing equipment. For aAdequate protection against contaminants at high level of concentrations in the ambient atmosphere, may be achieved only by breathing equipment may be the only possibility.

The APF/NPF indicates the theoretical best protection that can be achieved. But the specified protection factor might not be achieved in practice for various reasons. For example, if the equipment that relies on fitness to thea face seal does not fit have the right size and shape of for a worker’s face, the necessary required sealing property will not be possibleachievableed. In case of the mask respirator, it is manufactured in for limited ranges of size for workers of average build. It may be necessary to try different products of a similar specification to find mask respirator that is comfortable and gives a good fit and that provides thefor necessary protection. When choosing the mask, it is necessary to consider size or close adhesionfitness to the wearer's face not onlyas well as the protective efficiency.

The workers’ training must emphasize the need to of fitness and use correct usage of the mask for the good personal protection correctly each time.

Respirators

< Filtering face piece respirators>

Filtering face piece (FFP) respirators are made wholly or substantially of filter material which covers the nose and mouth. The nominal protection factor (NPF) of FFP respirators is relatively low. FFP respirators are mainly used for protection against low to moderately hazardous particles.

Their use helps to keep contaminated gloves away from the mouth area but they provide no protection for the eyes. And they and should not be used where when skin contamination is also concerneda hazard.

FFP respirators are easy to use and relatively inexpensive. They are usually disposable and designed to be used once, for a single use only, and so that they should not be reused.

The half face mask is a face piece made of rubber or plastic moulded to cover the nose and mouth and is held in place by adjustable straps. Air is drawn through one or more filters. The filters are contained built in one or more cartridges (canisters). The half masks NPFs of the half face mask are usually much higher than that of for filtering face piece respirators.

Two type of filters are available, one is for particulates (dust, fumes, mist) and the other is for gases and vapors. Specified Some gases and vapors are usually absorbed in a bed of activated carbon (charcoal).

It is necessary to note that the efficiency of the charcoal filter is easy toeasily decreases the performance when the moisture attached attaches to the charcoal. And it is also necessary to note it the half face mask is easy to slip off from the face than the full-face mask respirators.

A moulded full face mask made of rubber or plastic covers the entire face from just below the hairline to beneath the chin and is held in place with an adjustable head harness. Air is drawn through one or more filters. Various models of this type are manufactured.

The full face mask respirators NPFs of full face mask respirator are usually higher than that offor half face mask respirators. Two types of filters are available, one is for particulates (dust, fumes, mist) and the other is for gases and vapors. Specified Some gases and vapors are usually absorbed in a bed of activated carbon (charcoal).

It is necessary to note that the efficiency of the charcoal filter is easy toeasily decreases the performance when the moisture attached attaches to the charcoal.

Particulate filters could indicate the end of their useful lifetime by the increase in resistance to breathing. A Nnoticeable loss of resistance may indicate a hole or leak in filter or lacking of fitness to face seal. On the other hand, the absorption capacity of carbon (charcoal) filters cannot be tested and since there is no feasible method to establish know the residual absorption capacity of a used filters when it has once been used once.

TheHigh NPF of full face mask respirator could be obtained by its proper fitting to the face.offered against particles by a properly fitted full face mask respirator could be high. Therefore, confirmation of fitness is important. One of the easiest method to confirm its fitness is a leak check by wearers. The general method of leak check is as follows.

+ Cover the filter with hands and lightly inhale. If the mask stick to face, it means the mask is correctly worn. If air is leaking it can be recognized that air is passing through the gap between the face and padmask.

And it is necessary for the proper usage of the mask not to note never use the mask to obstruct the fitness of the mask or operation of air release valve to enterby insertion of beard, sideburns, and the forelock, etc. between the face seal and the face of respect body.

Powered air purifying respirators provide a flow of air into the mask in order to minimize inward leakage of contaminated air around an incomplete from the gap between the mask and face seal. Ideally, the The NPFs are higher than non-powered respirators. Filters for theThe powered respirators are available applicable for particulate contaminants, as well as gases and vapors. Powered respirator with full face mask type and the powered hoods type are commonly used.

The full face mask type with powered respirator commonly has two types commonly, one is provides a continuous flow of air into the mask, and another the other type is auxiliary breath-in type. The auxiliary breath-in type respirator feeds supplies fresh air to wearer linking with his breathing by the electric fan to assist inhalation. Auxiliary breath-in type with powered air purifying respirators are more economical with longer life of the filter and the battery is more economical than a constant flow type because it is equipped with filter and battery of longer life. In the case of the full face mask type with powered respirator, the face maskit gives the wearer enough time to escape from a contaminated area, even if the its ventilator fails.

The pPowered hoods with full completely cover of the head and areis made partially or totally of transparent material that to offers minimumminimize distortion or interruption of the wearer's vision. Contaminated air is drawn through one or more filters by a battery powered fan and the filtered air is fed supplied directly into the hood and is exhausted from the lower open part of hoods. The ventilator is usually mounted on a belt. Filters, as described above, are available for dusts, gases and vapors. Workers will need more extensive practical training to use powered hoods than is necessarythat for the RPE previously described. They should be able to prepared for being dependent on the equipment to provide an air supply by themselves. And they may need assistance to don and remove the Powered powered hoods.

These powered air purifying respirators are desirable under conditions of increased heavy workload because they make their breathing easier.

Breathing equipment

< Supplied-air respirators >

One of representative example of the supplied-air respirators is the breathing equipment with a compressed air line. A compressed air line may beis used to supply clean air to a face mask or hood. The air may be supplied from a compressor or from compressed air cylinders that are placed outside of the contaminated area. In using compressors, the air intake needs to be properly located to prevent the intrusion of contaminants becoming entrained ininto the air supply. And it is necessary to yield suplysupply breathable air of an acceptable quality by using in-line filters and traps.

< Self-contained breathing apparatus>

A self-contained breathing apparatus (SCBA) consists of a full face mask supplied with air or oxygen from compressed gas cylinders carried by the worker.

The air respiratory among part attached to the self-contained breathing apparatus (SCBA) have has two types; a demand type and a pressure demand type. As for the demand type, it became negative pressure inside the mask is created byat breathing and draws air is supplied from a cylinder. As for the pressure demand type, air is supplied at a constantly and pressure inside the mask is kept positive. As for the pressure demand type, there is a merit that radioactive substance is hard to come in from the outside for due to positive pressure inside.

Oxygen respiratory device have has the a structure that the oxygen respiratoryto be able to mix the compressed oxygen of from the oxygen cylinder with the expiration air that after removed removing carbon dioxide during expiration withby a carbon dioxide remover and reuse.

A self-contained breathing apparatus (SCBA) provides mobility but is bulky and heavy. Compressed air apparatus protects supplies air for up to several tens of minutes and oxygen apparatus for up to several hours. Extensive training is necessary for the wearers and for those who maintain the equipment.

11.3 4 Decorporation

Generic procedure for decorporation during a nuclear or radiological emergency is shown in the Generic procedures for medical response during a nuclear or radiological emergency (EPR-MEDICAL 2005 / Co-sponsored by IAEA and WHO), and described below about the main matter.

The explanation of decorporation is also given in Chapter 4.5 in this document.

Patients with a significant amount of internal contamination should be treated in order to reduce the radiation dose from absorbed radio nuclides and thus the risk of long term radiation effects. There are several approaches for minimizing internal contamination. The first is focused on reducing the absorption of radio nuclides and their deposition in target organs. The second approach aims to increase the excretion of the radio nuclides from the body.

Treatment procedures are most effective if it is initiated as soon as possible after contamination has occurred. Hence, in practice, the critical initial treatment decision has to be based on the emergency history, rather than precise dose estimates.

When deciding on decorporation, comparison is to be made between the benefit of removing the radioactive contaminants and the risk using modalities associated withof its significant side effects and the short and long term health effects of due to the contamination without when no decorporation treatment is carried out. Additional treatment should be based on more detailed reports of in-vivo measurements and bioassay. Decorporation treatment should be performed under the direction of a physician and includewith specific patient medical information history and conditions of the patient.

To correct the treatment in accordance with changed conditions of the internally contaminated patient, physicians need the results of evaluation of decorporation treatment efficiency. Follow up treatment could be based on data from early estimations of intake (bioassay measurements). This can be used as a good tool to verify the effectiveness of internal decorporation methods. The evaluation of the effectiveness of decorporation treatment may be performed by

+ comparing the total measured activity in urine and faeces with treatment to the predicted activity without treatment;

+ comparing the activity measured in specific organs or whole body with treatment to the predicted activity without treatment.

Guide for decorrporation treatment of each radionuclide are summarized in table in the document of EPR-MEDICAL 2005. Following tables are placed in the documents.

11.4 5 Iodine thyroid blocking

Accidents may involve the release of radioactive iodine. In such cases the thyroid is the organ most at risk and stable iodine tablets can be used to block the uptake of radioactive iodine. Stable iodine should be used only in the case of an emergency with release of radioactive iodine.

Potassium iodide (KI) is generally used as stable iodine tablets, generally for that purpose.

When taken at the appropriate dosage of KI and within the correct time interval around before and after exposure to radioactive iodine, KI saturates iodine content in the thyroid gland saturates with stable (non-radioactive) iodine. As a result, radioactive iodine will not be taken up in thyroid and stored by the thyroid glandexcrete into urine. Any iodine which exceeds the thyroid’s requirement amount required for production of thyroid hormones in thyroid (either non-radioactive or radioactive) will be excreted through the urine within two days.

To obtain the maximum reduction of the radiation dose to the thyroid, stable iodine should be administered before any intake of radioiodine; otherwise, or as soon as practicable thereafter. If stable iodine is administered orally within the six hours preceding the intake of radioactive iodine, the protection provided is almost complete; if stable iodine is administered at the time of radioiodine inhalation, the effectiveness of thyroid blocking is about 90%. The effectiveness of the protective measure decreases with the delay of its administration., but Tthe uptake of radioiodine can be reduced to about half if blocking is carried out within a few hours of inhalation [201].( EPR-MEDICAL 2005)

KI tablets should be taken by individuals only when explicitly instructed to do so by supervisor or competent authority [212].

(IAEA-TECDOC-1162 Generic procedures for assessment and response during

a radiological emergency)

The generic intervention levelcriteria for iodine thyroid blocking from in the international guidance is provided as shown in the following table in [213].GSG-2 ’’ Criteria for Use in Preparedness and Response for a Nuclear or Radiological Emergency’’.

The risk of side effects from of KI increases with age, while the risk of radiation-induced thyroid cancer in individuals over 40-years old is low. For this reason, thyroid blocking with KI is not generally indicated in adults over 40 years of age until nowrecently. But, some recent study shows the risk seems to remains risk in even among the elderly persons of a thing decreasing with age[214]. So Therefore, it is desirable to dose administer KI to an applicant even ifpersons over older than 40 years old as well.

If stable iodine prophylaxis is performed, it is desirable to make sure that information about persons who took stable iodine is recorded. The information could beincludes individualized name, daily and total dosage, etc.

From the intake of stable iodine, tThere is a probability possibility to have theof side effects of stable iodine. The effectsthat differ widely according to the amount of iodine regularly taken in the diet and the prevalence presence of thyroid diseases (which is very much higher among elderly people than among infants and young persons). The sSide effects of stable iodine administration include sialadenitis, gastrointestinal disturbances, allergic reactions, and minor rashes, iodine-induced thyrotoxicosis, transient hypothyroidism and goitre. Stable iodine should be administered with caution for the persons in following categories, as they have relative contraindication for taking stable iodine [201]:

+ thyroid disease, past or present;

+ iodine hypersensitivity;

+ dermatitis herpetiformis;

+ hypocomplementaemic vasculitis. ( EPR-MEDICAL 2005)

11.5 6 Personal shielding

Personal shielding is accomplished generally by generally wearing the shielding suit. Several kinds of shielding suits are manufactured. One of the typical example of the shielding suit is the ahas shielding in both side of chest and back of the bodybest, they are which is made of materials that contains tungsten, lead or special rubber. So that tThe shielding best has double side shielding andcan shield the chest and the back of the body against radiations scattered behind the body.

Wearing a shielding best for prolonged periods is tiringtiresome, which is why garments do not incorporate more substantial shielding. The shielding bests may slow down working performance and require more time to accomplish the job. So that it may and thus result in receiving higher personal doses. Shielding best must be stored by a the method shown by the manufacturer. Folding Wrong folding or creasing creases may causes cracks or wear in the shielding materials. Damaged shielding bests should be discarded or clearly labeled as being only for uses other than as a body radiation shield.

Shielding suit of the cover oaroveralls type made of special cloth is also manufactured also. This type shielding suit has relatively high attenuate effectgood protection for low energy gamma ray radiations or beta ray radiations, but it is lownot enough for relatively high energy radiations.

11.6 7 Personal hygiene

11.67.1 Food and drinking water monitoring for workers

The securing of the food and drinking water for the worker in the emergency should be practically served with food and drinking water storedby storage for emergency and or the supply supplied from the outside of an emergency site. For this purpose, it is important that storing the food and drinking water of enough quantity of food and drinking water is stored for emergency and securing the supply route in emergency stage from the outside of to the emergency site is established in the preparation stage. It is because the background radiation levels might be increased and it is not practicable In addition, it is not practicable to perform enough proper monitoring of food and drinking water because of the rising of the background level of the measurement by the accident. Therefore, the securing of the food and drinking water for the worker in the emergency should be considered mainly storage of enough quantity and supply from the outside of the site.

11.67.2 Sanitary aspects

In the emergency, the management of sanitary aspect of the worker is also important also. Because a great many workers will enter the accident site for the accident response, the prevention and the prevention of the spread of infectious diseases among the worker are particularly important. Specifically, it isEspecially infection prophylaxis to influenza or caution of food poisoning (norovirus etc.) and the prevention ofare important to prevent their spread of them.

The following are examples of reasoningcautious management.

< Influenza>

+ Enforcement of hand-washing and a gargle.

+ Influenza vaccination.

+ Preparation of infection prevention goods.

+ Announcement and education for the infection prevention.

+ Searching for the fever-stricken (by using the thermography etc.).

+ Enforcement of hand-washing and the worker’s physical condition management.

+ Sanitary management during food preparation.

+ Clarification of the response when the occurrence of the food poisoning

+ Announcement and education for the infection prevention

Establishment Provision of the medical room on site and placement of doctor or medical staff are effective incare service near the site is advisable for the sanitary management of sanitary aspect also, if needed.

11.67.3 Prevention of heat stroke

Especially during emergency maintaining the health condition of the workers is important to smoothly conduct required response works as scheduled. Followings are essential aspects should be paid more attention as precautionary measures.

✓ Lack of sleep

✓ Hangover

✓ Diabetes

✓ Hypertension

✓ Heart trouble

✓ Kidney trouble

✓ Fever

✓ Diarrhea

✓ Working environment of very cold or hot

Heart stroke is the most common problem encountered especially during hot seasons.

For prevention of the heat stroke, following measures are generally effective.

+ Using WBGT (*), changes in work timeworking hourss, frequency and times duration of breaks, and work loadintensity were made should be adjusted.

+ Work under the blazing sun is prohibited in principle.

( For example; prohibited from 14:00 to 17:00 in hot season)

+ Appropriate rest and frequent intake of water and salt are encouraged.

+ Physical management using check sheets.

(check Check health conditions before and after work)

+ Wearing cool vests.

+ Establishment of a work environment that workers are allowed to claim poor ly condition.

+ Establishment of an environment e that early diagnosis at the medical room is encouraged.

+ Implementation of measures to enhance increasing adaptability to the working the environments.

+ Education and instruction of the way to prevent heat stroke measures.

* WBGT: The WBGT index is an empirical index.  It represents the heat stress to which an individual is exposed.  The index was developed specifically for use in industrial settings. The WBGT-index combines three measurements: natural wet-bulb temperature, globe temperature and air temperature.Index using three perspectives of humidity, radiation heat, and temperature, which have a considerable impact on the heat balance of human bodies

And it is very important to take each measure to preventfor the prevention of heat stroke were started from the time towards the hottestbefore hotter season starts.

In the emergency in particular, the worker may often puts on many personal Some protective equipmentsequipment which may increase of the physicalwork load of the worker, it need to attention to invite and cause heat stroke easily. Therefore, parallel in addition to the measures mentioned above, it is necessary to improveimproving the work environment is effective for the prevention of heat stroke also. The following methods are exemplified.

+ Introducing Use of protective suits with good breathability.

+ Expansion of area wearing full-face masks is not requiredLimiting the area where full-face mask is required.

+ Setting Provision of a rest stations area near workplace

11.67.4 Mental health

In During emergency stage, workers may have to work carry out their job with under multiple stressors such as potential risks of radiation exposure and other troublesoccupational risks. It is important, therefore, to take care of the worker’s mental health of the workers as well as management not only their physical health management.

The mental health support by the an expert on mental health in the following procedures is effective for example.is provided, if necessary. Following is the example for that approach.

(Example)

+ To confirm stress andpay attention to mental health status of workers.

+ To provide personal counseling with those who have high risk of mental health disorder.

+ To inform them and their employersthe workers of the availabilityof cautions at work of the counseling services.

+ To introduce them to medical institutions etc. if needed.

References

[211] INTERNATIONAL ATOMIC ENERGY AGENCY, Practical Radiation Technical Manual, Personal protective equipment, IAEA-PRTM-5, IAEA, Vienna (2004).

[212] INTERNATIONAL ATOMIC ENERGY AGENCY, Generic procedures for assessment and response during a radiological emergency, IAEA-TECDOC-1162, IAEA, Vienna (2000).

[213] INTERNATIONAL ATOMIC ENERGY AGENCY, Criteria for Use in Preparedness and Response for a Nuclear or Radiological Emergency, IAEA SAFETY STANDARDS SERIES No. GSG-2, IAEA, Vienna (2011).

[214] Preston, L.D., et al. Solid Cancer Incidence in Atomic Bomb Survivors: 1958-1998. Radiation Research 168, 1-64, 2007.

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Non-woven permeable

Coverall

(Example)

Water proof cloth

Anorak

(Example)

[pic]

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N95 respirator

(Example)

Surgical mask

(Example)

[pic]

[pic]

Dust filter

Charcoal filter

Half face mask respirator

(Example)

Dust filter

Full face mask respirator

(Example)

[pic]

Charcoal filter

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Powered hoods

(Example)

Full face mask powered respirator

(Example)

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Oxygen respiratory

(Example)

Air respiratory

(Example)

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GENERIC CRITERIA FOR PROTECTIVE ACTIONS AND OTHER RESPONSE ACTIONS IN EMERGENCY EXPOSURE SITUATIONS TO REDUCE THE RISK OF STOCHASTIC EFFECTS

| Generic criteria |Example of protective actions and other response actions|

|Projected dose that exceeds the following generic criteria : Take urgent protective actions and other response actions |

|H Thyroid |4568:;HIKòæÚÑƶ¢ŽwcwL450 mSv in the first 7 | Iodine thyroid blocking |

| |days | |

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Shielding best

--Special rubber

(Example)

Shielding best

--Tungsten

(Example)

Shielding suit

--Special cloth

(Example)

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Searching for the fever-stricken via thermography

[pic]

Influenza Vaccination

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Poster for attracting attention

(Influenza & Norovirus)

Left: Cool vest, Right: Cool scarf

Poster on heat stroke prevention

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WBGT detector (handy type)

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