Masking the issue
September 1st 2008

If your workers are exposed to airborne hazardous substances, respiratory protection equipment (RPE) is the last thing they need. The COSHH approved code of practice lists a hierarchy of control measures such as enclosure and ventilation which should be explored first, and only if the hazard cannot be mitigated any other way should respiratory protective equipment be considered says JSP

There are 17,000 new cases of occupational asthma each year, and that there would be 4,000 fewer deaths from chronic obstructive pulmonary disease if occupational dusts, smoke and fumes were removed from the cocktail of workplace contaminants.

The Health and Safety Executive (HSE) is committed to reducing work related respiratory illness, and its latest move was the introduction of Workplace Exposure Limits (WEL), brought into force by amendments to the control of Substances Hazardous to Health (COSHH) Regulations in early 2005. Most substances including gases and vapours have now been assigned exposure limits for short and long time frames, and are listed in the HSE publication EH40. For example, exposure to hydrogen chloride as a gas or aerosol mist at one part per million is permitted for eight hours, but only for 15 minutes if at a 5 part per million level.

An effective risk assessment will look for the most common hazards, which can be grouped as dust, mist, fume, vapour, gas and oxygen deficiency or enrichment. In determining the nature and extent of the risk it will: Identify the substances or processes, and the people at risk.

Determine the type of respiratory hazard created by each substance or process.

Research the likely health effects of these substances.

Assess the levels of exposure and compare these to workplace exposure limits.

Evaluate control measures.

The assessment will determine the nature of the hazard and whether it can't be mitigated by the hierarchy of control measures established by COSHH. If mitigation is not an option it will have established the concentration and the 24 hour exposure levels of workers which will be needed in the selection of respiratory protection.

The equipment can be divided into two categories, air filtering and air supplying. Both types should be CE marked to the PPE directive, and provide effective protection for the wearer. They should be comfortable and easy to operate, fit correctly, be compatible with any other PPE being used and be stored in an area free from contamination when not in use.

The main types (with European Standard) are as follows: EN12941 Powered Hoods and Helmets. Designed for protection against particulates, gases and vapours. Three protection classes are given.

EN136 Full Face Masks. Designed for use with particulate and gas filters.

Covering the whole face, manufactured in a flexible material such as flexible rubber or silicone.

EN140 Half Masks. Designed for use with particulate and gas filters. Covering half the face, manufactured in a flexible material such as flexible rubber or silicone.

EN405: Maintenance Free Half Mask Respirators. These come fitted with gas/dust or combination filters covering the nose, mouth and chin requiring no maintenance or spare parts. Simply discard when filters are exhausted or within 28 days, whichever occurs first, for exemption from record keeping and the maintenance requirements of COSHH regulations.

EN149 Filtering Face Piece for Particulates Designed to cover the nose, mouth and chin. The construction is made of the filter material itself. Designed to be disposed of after each period of work or shift 8hr.

EN14387 Gas and Vapour Filters. Filters for gases and dusts that can be fitted to either half mask (EN140) or full face mask (EN136).

EN143 Particulate Filters. Filters for dust that can be fitted to either half masks (EN140) or full face masks (EN136) The filters are colour coded to indicate which gas/vapour or duct they are designed to be effective against. The assigned protection factor is the level of protection that a wearer can reasonably expect from a mask, and can be used with the workplace exposure limit to determine the maximum concentration that can be worked in when wearing that particular mask.

For example: If Xylene is present in the environment at a concentration of 300ppm, and the workplace exposure limit is 50ppm, the necessary protection factor is therefore 6 (6x50 = 300).

The regulations and technology now exist to challenge the 40 conditions which affect the lungs and airways, ranging from asthma to lung cancer. Some conditions such as mesothelioma can take 60 years to develop, and while little can be done for the 3,000 people who die each year as a result of exposures to asbestos when Harold Wilson was in government, it is time to consign that kind of tragedy to our industrial past.

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