An Workplace Exposure Limit is an upperlimit on the acceptable concentration of a hazardous substance in workplace air for a particular material or class of materials. It is typically set by competent national authorities and enforced by legislation to protect Workplace safety and health.
Types of Exposure Limit:
Short term exposure limit (STEL)- maximum concentration of airborne contaminates too which employees may be exposed for a short period of time equal to 15 minutes.
Long term exposure limit (LTEL)- maximum concentration of airborne contaminants to which employees may be exposed over their entire working life for a reference period equal to 8 hours per day, 40 hours per week.
Purpose of WELs
The purpose of WEL is to combat the ill-health effects of being exposed to very high levels of the substance for quite short periods of time (sudden acute effects), and also to combat the ill-health effects of being exposed to relatively low concentration of substance for prolonged period or all hours of working day through an entire working life time (delayed chronic effects).
The aim is to ensure that the exposure to contaminants is below WEL, by having arrangements for monitoring the concentration of airborne substance in workplace along with suitable controls such as extraction system.
Types of Exposure Limit:
Short term exposure limit (STEL)- maximum concentration of airborne contaminates too which employees may be exposed for a short period of time equal to 15 minutes.
Long term exposure limit (LTEL)- maximum concentration of airborne contaminants to which employees may be exposed over their entire working life for a reference period equal to 8 hours per day, 40 hours per week.
Purpose of WELs
The purpose of WEL is to combat the ill-health effects of being exposed to very high levels of the substance for quite short periods of time (sudden acute effects), and also to combat the ill-health effects of being exposed to relatively low concentration of substance for prolonged period or all hours of working day through an entire working life time (delayed chronic effects).
The aim is to ensure that the exposure to contaminants is below WEL, by having arrangements for monitoring the concentration of airborne substance in workplace along with suitable controls such as extraction system.
Limitations of WELs
Workplace exposure limits are set based on inhalation, whereas other routes are not considered. They are set with reference to male physiology of certain European countries and USA, hence it will have significant impact on race and gender.
Workplace exposure limits are set based on inhalation, whereas other routes are not considered. They are set with reference to male physiology of certain European countries and USA, hence it will have significant impact on race and gender.
They becomes invalid if the environmental parameters, such that humidity temperature etc. in which the tests are carried out, vary largely with actual workplace environment. They don’t account for synergistic effect of multiple substances.
Some limits are only ‘guidelines’. Some limits do not consider all the possible health effects of a substance such as dermatitis would not be considered with an airborne limit.
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