Pollutant

Concentration in mircograms per cubic metre (i)

Health effects of
pollutant at
elevated ambient
levels

1 Hour
(ii)

8 Hours
(iii)

24 Hours
(iii)

3 Months
(iv)

1 Year
(iv)

Sulphur Dioxide

350

80

Respiratory illness; reduced lung function; morbidity and mortality rates increase at higher levels.

Total Suspended particulates

260

80

Respirable fraction has effects on health.

Respirable Suspended Particulates (v)

180

55

Respiratory illness; reduced lung function; cancer risk for certain particles; morbidity and mortality rates increase at higher levels.

Nitrogen Dioxide

300

150

80

Respiratory irritation; increased susceptibility to respiratory infection; lung development impairment.

Carbon Monoxide

30 000

10 000

Impairment of co-ordination; deleterious to pregnant women and those with heart and circulatory conditions.

Photochemical Oxidants (as Ozone) (vi)

240

Eye irritation; cough; reduced athletic performance; possible chromosome damage.

Lead

Affects cell and body processes; likely neuropsychological effects, particularly in children; likely effects on rates of incidence of heart attacks, strokes and hypertension

(i)

(ii)

Not to be exceeded more than three times per year.

(iii)

Not to be exceeded more than once per year.

(iv)

Arithmetic means.

(v)

Respirable suspended particulates means suspended particles in air with a nominal aerodynamic diameter of 10 micrometres and smaller.

(vi)

Photochemical oxidants are determined by measurement of ozone only.