Threshold Limit Value
refers to the airborne concentration of substances and conditions which workers
may be repeatedly exposed day after day without adverse effect.
refers to the airborne concentration of substances and conditions which workers
may be repeatedly exposed day after day without adverse effect.
Types of Threshold
i.) Threshold Limit Value – Time Weighted Average (TLV – TWA): This is the concentration
for a normal 8 hours working and a 40 hour work week to which nearly all
workers may be repeatedly exposed, day after day without adverse effect.
for a normal 8 hours working and a 40 hour work week to which nearly all
workers may be repeatedly exposed, day after day without adverse effect.
ii.) Threshold
Limit Value – Short Term Exposure Limit (TLV – STEL): The concentration to
which workers can be exposed continuously for a short period of time without
suffering from irritation, chronic or reversible tissue damage, narcosis of sufficient degree to increase the
likelihood of accidental injury, impair self rescue or materially reduces work
efficiency, etc.
Limit Value – Short Term Exposure Limit (TLV – STEL): The concentration to
which workers can be exposed continuously for a short period of time without
suffering from irritation, chronic or reversible tissue damage, narcosis of sufficient degree to increase the
likelihood of accidental injury, impair self rescue or materially reduces work
efficiency, etc.
iii.) Threshold
Limit Values – Ceiling (TLV – C): Is the concentration that should not be
exceeded during any part of the working exposure.
Limit Values – Ceiling (TLV – C): Is the concentration that should not be
exceeded during any part of the working exposure.
Factors Affecting Threshold Limit Value
·
Level of concentration of substance in the
environment.
Level of concentration of substance in the
environment.
·
Toxicity of substance.
Toxicity of substance.
·
Epidemiological findings of the substance.
Epidemiological findings of the substance.
·
Physical and chemical properties of the
substance.
Physical and chemical properties of the
substance.
·
Frequency of exposure of substance.
Frequency of exposure of substance.
·
Individual differences in tolerance.
Individual differences in tolerance.
