For using Toluene under the Air Toxics Hot Spots Programs, the OEHHA has released a new notice on adopting some Reference Exposure levels on Aug 20, 2020.

Reference Exposure Levels (RELs) are nothing but the concentration of an air-bonechemical that is not anticipated to show intense non-cancer health effects on the general public including sensitive subpopulation for a specified duration of Exposure. To develop guidelines for health risk assessments OEHHA was required to calculate the RELs of certain airborne pollutants including Toluene.

OEHHA’s adoption classifies the types of exposure of toxic substances in the air as follows:

● Acute REL- Infrequent 1-hour exposures

● 8–Hour REL- repeated 8-hour exposures

● Chronic REL- continuous long-term exposures



OEHHA has developed the REL levels of the Toluene by using the “Air Toxics Hot Spots Program Technical Support Document for the Derivation of Nonc-ancer Reference Exposure Levels “. Toluene has been already placed under the list of “Toxic Air Contaminants that may disproportionately impact children, according to Health and Safety Code Section 39669.5(b)(1)” The major reason for this is the neurotoxic effects on Human especially children than adults.

The REL values of Toluene are as follows:

● Acute REL- 5,000 µg/m3

● 8–Hour REL- 830 µg/m3

● Chronic REL- 420 µg/m3 long-term exposures

Reference link:

Exposure level can be found under the following link:


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