Table 1.

Ambient Air Quality Standards (WHO, 2011–2013).

Pollutant		WHO Standard
Sulfur Dioxide		20 μg/m3 (24-h mean) 500 μg/m3 (10-min mean)
Nitrogen Dioxide		40 μg/m3 (annual mean) 200 μg/m3 (1-h mean)
Carbon Monoxide		10 mg/m3(8-h mean) 30 mg/m3(1-h mean)
Particulate Matter	PM2.5	10 μg/m3 (annual mean) 25 μg/m3 (24-h mean)
	PM10	20 μg/m3 (annual mean) 50 μg/m3 (24-h mean)
Ozone		100 μg/m3 (8-h mean)