Respro - Urban Survival Equipment

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• Avian Influenza
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• Do masks really work?
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• Understanding OEL

Understanding OEL

Within the work place environment an assessment of risk is normally carried out by a health and safety officer within the company. The officer would determine the level of risk by measurement of the level of particulate and specify appropriate measures including the specification of respiratory equipment for use in the work place environment.

Respiratory equipment is usually specified on the basis of an exposure limit of all hazardous material likely to be either inhalable or respirable. These levels are determined by the HSE (Health and Safety Executive) and are used as the basis for the specification of respiratory protection equipment. The exposure limit will vary according to the toxicity or hazardous nature of the material.

For example the exposure limit for airborne aluminium particulate is 10mg/m3 as listed by the HSE. If a risk assessment is carried out and it is found that the levels of Aluminium dust are measured at 40mg/m3 then the correct specification for the mask must be at least four times the exposure limit as set by the HSE. If the levels were 100mg/m3 then the mask specification must be at least ten times the exposure limit.

All masks specified must conform to a standard, whether it be a European or American standard otherwise it cannot be specified for use. For particulate matter the European standard is EN149 with various protection levels within it P1, P2,or P3. The Alpha masks offer a range of protection levels: 4.5 x OEL (P1), 12.5 x OEL (P2) and 50. x OEL (P3). 1n the above case, we would recommend the P1 mask for the environment measured 40mg/m3, as this would give adequate protection for concentrations up to 45mg/m3 and P2 for the environment measured at 100mg/m3, as this would give adequate protection for concentrations up to 125mg/m3.

Al masks that conform to EN149 are tested with a particle size of 0.5 microns. Should the assessment reveal a predominance of particulates less than 0.5 microns then an alternative respiratory unit like a supplied air system, or full BA must be specified.