Monitoring the environment

Monitoring investigation levels for air toxics

The National Environment Protection Council made the National Environment Protection (Air Toxics) Measure in 2004. The monitoring investigation levels are the concentrations of an air toxic which, if exceeded, requires an appropriate form of further investigation and evaluation.

Pollutant Averaging period Monitoring investigation levels
Benzene Annual 3 ppb
Benzo(a)pyrene Annual 0.3 ng/m3
Formaldehyde 24 hours 40 ppb
Toluene 24 hours

1000 ppb
100 ppb


24 hours

250 ppb
200 ppb

Annual: the annual average concentrations are the arithmetic mean concentrations of 24-hour monitoring results.

24 hours: monitoring over a 24-hour period is conducted from midnight to midnight.

ppb: parts per billion (for every billion litres of air there is one litre of the pollutant)

ng/m3: nanograms per cubic metre (1 billionth of a gram per cubic metre)

Page last updated on 23 Oct 2013