Workplace Exposure Standards for Airborne Contaminants

Question 1

Time weighted average (TWA)

Answer 1

During periods of daily exposure to an airborne contaminant, exposure above this value is
permitted for short periods, if they are compensated for by equivalent exposures below the
exposure standard during the working day

Question 2

Short term exposure limit (STEL)

Answer 2

The STEL is a 15 minute time weighted average exposure limit which must not be exceeded at any
time during an eight hour working day, even if the exposure during the full day is less than the
TWA exposure standard. Exposures at the STEL must not be longer than 15 minutes and must not be repeated more than four times per day. There must be at least 60 minutes between successive
exposures at the STEL.

Question 3

What is the Respirable Dust exposure limit? (note; this is listed as coal dust in the table)

Answer 3

1.5mg/m^3

Question 4

What is the Respirable Crystalline Silica-Containing Dust exposure limit? (note;

Answer 4

0.05mg/m^3

Question 5

What is the Inhalable Dust exposure limit?

Answer 5

10mg/m^3

Question 6

What is the Diesel Particulate Matter exposure limit

Answer 6

0.01mg/m^3