Ambient air quality standards
1. Ambient concentrations of ozone (O3) may not exceed -
(a) an instant peak of 0.25 parts per million measured at 25ºC and normal atmospheric
pressure; or
(b) a one-hour average of 0.12 parts per million measured at 25ºC and normal atmospheric
pressure.
2. Ambient concentrations of the oxides of nitrogen (NOX) may not exceed -
(a) an instant peak of 1.4 parts per million measured at 25ºC and normal atmospheric
pressure;
(b) a one-hour average of 0.8 parts per million measured at 25ºC and normal atmospheric
pressure;
(c) a 24-hour average of 0.4 parts per million measured at 25ºC and normal atmospheric
pressure and the 24-hour limit may not be exceeded more than three times in one year;
(d) a one-month average of 0.3 parts per million measured at 25ºC and normal atmospheric
pressure; or
(e) an annual average of 0.2 parts per million measured at 25ºC and normal atmospheric
pressure.
3. Ambient concentrations of nitrogen dioxide (NO2) may not exceed -
(a) an instant peak of 0.5 parts per million measured at 25ºC and normal atmospheric
pressure;
(b) a one-hour average of 0.2 parts per million measured at 25ºC and normal atmospheric
pressure;
(c) a 24-hour average of 0.1 parts per million measured at 25ºC and normal atmospheric
pressure and the 24-hour limit may not be exceeded more than three times in one year;
(d) a one-month average of 0.08 parts per million measured at 25ºC and normal
atmospheric pressure; or
(e) an annual average of 0.05 parts per million measured at 25ºC and normal atmospheric
pressure.
4. Ambient concentrations of sulphur dioxide (SO2) may not exceed -
(a) a ten-minute average instant peak of 0.191 parts per million measured at 25ºC and
normal atmospheric pressure;
(b) an instant peak of 500 micrograms per cubic meter (Ig/m3) measured at 25ºC and
normal atmospheric pressure;
(c) a 24-hour average of 0.048 parts per million or 125 micrograms per cubic meter (Ig/m3)
measured at 25ºC and normal atmospheric pressure;
(d) an annual average of 0.019 parts per million or 50 micrograms per cubic meter (Ig/m3)
measured at 25ºC and normal atmospheric pressure.
5. Ambient concentrations of lead (Pb) may not exceed a one-month average of 2.5 micrograms
per cubic meter (Ig/m3).
6. Ambient concentrations of particulate matter with a particle size of less than 10 microns (I) in
size (PM10) may not exceed -
(a) a 24-hour average of 180 micrograms per cubic meter (Ig/m3) and the 24-hour limit
may not be exceeded more than three times in one year; or
(b) an annual average of 60 micrograms per cubic meter (Ig/m3).
7. Ambient concentrations of total suspended solids may not exceed -
(a) a 24-hour average of 300 micrograms per cubic meter (Ig/m3) and the 24-hour limit
may not be exceeded more than three times in one year; or
(b) an annual average of 100 micrograms per cubic meter (Ig/m3).