Occupational Exposure Limits

OCCUPATIONAL EXPOSURE LIMITS
Around 400 substances have been given A Workplace Exposure Level (WEL) that must not be exceeded. Most WELs are given as 8-hour time-weighted averages with a short term (15 minute)maximum within that.

Few of the substances encountered in the meat industry have a WEL, but there may be some. Certain areas like QC laboratories may use a range of solvents and other chemicals. Some cleaning products may give of fumes that contain chemicals that have a WEL. There is a WEL for carbon dioxide. Argon and nitrogen do not have WELs and are not directly harmful. However, they can act as asphyxiants. In areas where gases of this type are used it may be necessary to monitor oxygen levels.

There is a general WEL for all inhalable dusts of 10mg. per cubic metre over 8 hours or 4 mg. per cubic metre for dust that is fine enough to be respirable (i.e. breathed deeper into the lungs).

However some dusty materials will have their own WEL.
For substances that cause asthma, cancer or inheritable genetic damage, exposure must be reduced below any WEL to the lowest level reasonably practicable.

Flour dust, for example, is an occupational asthmagen. It has a WEL of 10 mg per cubic metre of air over 8 hours, with a short term limit of 30 mg per cubic metre over any 15 minute period.
But because it causes asthma the legal duty is to get exposure as far below that standard as is reasonably practicable.