Respirators are face masks worn to prevent the inhalation of harmful particles in the air. They are the first line of defense against asbestos dust environments. There are two main types of respirators:
These use filters, cartridges, or canisters to remove contaminants from the air you breathe.
These provide you with clean air from an uncontaminated source such as a source of pure oxygen or compressed clean air.
For protection against asbestos dust, our need is for air-purifying filters. It can be a half-face or full-face mask A half-face shields the nose and the mouth. A full-face mask covers mouth, nose and eyes – these are usually for protection against gases and vapours.
A mask needs to be tight-fitting to realize its proper function. This means the face piece must fit tightly around the nose. In fact, since swallowed asbestos can be harmful as well, the proper facemask must cover both nose and mouth snugly. The tight fit on the nose is accomplished with a flexible seal like a rubber lining between the respirator and the face of the user in order to work properly. Therefore, anything that interferes with the respirator seal is not permitted when using this type of respirator. This could include facial hair, earrings, head scarves, and facial piercings. Two simple pressure checks are used to check tight fit.
The positive-pressure test is conducted by covering the exhalation valve with the palm of the hand and exhaling gently. The face piece should puff or bulge slightly away from the face without allowing air to escape. If face air leakage is detected, re-position the respirator on the face and/or adjust the tension of the elastic straps to eliminate the leakage. Repeat the test once more.
For the negative-pressure test, attach the respirator to the face, place palms to cover the air inlets and then inhale. A slight collapse of the face piece with no air leakage indicates a satisfactory fit. (The illustration below is from the web site of the Construction Safety Association of Ontario, Canada.)
The measure of a respirator’s protection capability is called the Assigned Protection Factor or APF. It represents the level of protection from airborne exposure each class of respirators is expected to provide. The larger the number, the greater the level of protection. For example, when used properly, a respirator with an APF of 10 will reduce your exposure to 1/10th the concentration of the contaminant in the air. Similarly, a respirator with an APF of 50 will reduce your exposure to 1/50th the concentration of the contaminant in the air.
Canada and USA follow the standards of the U.S. National Institute for Occupational Safety & Health (NIOSH) regarding regarding respirators. Visit www.ccohs.ca or the NIOSH web site.
In North America one may hear someone refer to a respirator as an “N95” or a “P100” which describe the type of filter material and its protective properties.
The first part of the filter’s classification uses the letters N, R, or P to indicate the filter’s ability to function when exposed to oils.
This rating is only important in work settings where oils may be present, because some oils can reduce the effectiveness of the filter.
The second part of the classification — the number– refers to the filter’s ability to remove the most-penetrating particle size during “worst case” testing.
Filters that remove at least 95 percent of these particles are given a 95 rating. Those that filter out at least 99 percent receive a 99 rating, and those that filter out at least 99.97 percent – essentially 100 percent – receive a 100 rating.
Using this classification method, an N95 filter is not resistant to oil but removes at least 95 percent of the most-penetrating particles. It should now be clear that one should use a respirator with a P100 rating that is a P against asbestos.
Australia has had long experience with asbestos and the harm of asbestos is now deeply understood there. Australia mined as well as consumed asbestos until recently and has now banned its use. Australian Standard AS/NZS1716 on a disposable or catridge respirator means you are safe to use it against asbestos dust. As you can see, NZS stands for New Zealand.
Bureau of Indian Standard 2008 Edition, Section 9623, Selection, Use and Maintenance of Respiratory Protective Devices – Code of Practice, subsection 5.3.3 states that asbestos can produce cancer in some individuals after ‘latent’ period of 20 to 40 years. Section8.3.1 states that “air purifying particulate filters are classified as P1, P2 and P3 according to their filtering efficiency as per IS 15322 and IS 9473. Filter efficiency is commonly tested using a 0.3-micron NaCl or Paraffin oil aerosol. The 0.3-micron size is the most penetrating size for particulate filters. Therefore, respirators will filter all other particle sizes at least as well as the certified efficiency level.” P3 in India is the P2GV in Australia.
The 3M company claims that their 3M 8710 respirator available in India has been tested and meets the performance requirements of AS/NZS 1716-1994 and has been approved by WorkCover NSW – Approval Number 938. The product is also certified by Standards Australia, Licence No. 707. 3M claims that 8710 respirator has been classified as a P1 particulate filter and is intended for use against mechanically generated particulates including silica and asbestos.
It is interesting that India has detailed prescriptions on these respirators although this has not reached the asbestos factory floors or the labourers involved with the transportation, storage and sale of asbestos sheets and other products.
Different countries have different standards numbers and respirators labeled with those numbers must be consulted to provide adequate protection.
Leave the respirator on until the contaminated clothing is removed, bagged and sealed. Clean the mask (excluding filters and cartridges) by immersing in warm cleaning solution – not containing lanolin and other oils – and scrub with soft brush until visually clean. Rinse in fresh, warm water and air-dry in non-contaminated atmosphere and leave there for a few hours. Store in a resealable bag in dry atmosphere in ambient temperature.
Bureau of Indian Standard 9623/ 13.5.1 on respirators states this: “After inspection, cleaning and necessary repair, respirators should be stored to protect against dust, sunlight, heat, extreme cold, excessive moisture or damaging chemicals. Respirators placed at stations and work areas for emergency use should be stored in compartment built for the purpose, be quickly accessible at all times and be clearly marked. Routinely used respirators, such as dust respirators, may be placed in plastics bags. Respirators should not be stored in such places as lockers or tool boxes unless they are in carrying cases or cartons.”