Threshold Limit Values for Chemical Substances. Adopted by ACGIH with Intended Changes. Policy Statement. The TLVs (Threshold Limit Values) are designed as guidelines to have a control on health hazards.
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Adopted by ACGIH with Intended Changes
This is the concentration averaged over an 8 hr. workday and a 40 hr. workweek, to which the worker may be xeposed day after day without adverse affect.
Acetophenone - 10 ppm.
Carbon monoxide - 25 ppm.
Benzene - 10 ppm.
Cobalt carbony - 0.1 ppm.
Formic acid - 5 ppm.
The concentration to which workers can be exposed continuously for a short period of time without suffering from
* where : TLV-TWA is threshold limit value-Time weighted average.
If, TLV = c1/t1+c2/t2+....cn/tn
exceeds unity, then the Threshold Limit of the mixture is considered to be exceeded.
c1,c2…. cn are concentrations of different substances in a mixture, and
t1,t2…. tn are TLVs of corresponding substances.
The particle size-selective TLVs (PPS-TLVs) are expressed in 3 forms:
Inhalable particulate -TLV-TWA 10mg/m³.
Respirable particulate - TLV-TWA 3 mg/m³.
Physical factors which act adversely to increase the toxic response of a substance are :
These may place added stress on body, TLVs have built-in safety factors to guard against adverse effects to moderate deviations but not gross deviations.
(TLV in ppm)*(gram molecular weight of substance) /24.45
(TLV in mg/m³)*(24.45)/(gram molecular weight of substance).