Table 2.
WHO air quality guideline values (AQG), number of countries with air quality standards (AQS) and percentage of countries compliant with WHO recommendation for the classical pollutants PM2.5, PM10, ozone, NO2, SO2 and CO for various short- and long-term averaging times
| Short-term ambient air quality standards | Long-term ambient air quality standards | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 24-h (µg/m3) | PM10 24-h (µg/m3) | O3 1-h (µg/m3) | O3 8-h daily max (µg/m3) | NO2 1-h daily (µg/m3)mean | NO2 24-h (µg/m3) | SO2 10-min (µg/m3) | SO2 1-h (µg/m3) | SO2 24-h (µg/m3) | CO 15-min (mg/m3) | CO 1-h (mg/m3) | CO 8-h (mg/m3) | CO 24-h (mg/m3) | PM10 1-year (µg/m3) | PM2.5 1-year (µg/m3) | NO2 1-year (µg/m3) | SO2 1 year (µg/m3) | |
| No. of countries with AQS | 39 | 101 | 40 | 70 | 77 | 45 | 9 | 71 | 100 | 8 | 52 | 87 | 12 | 83 | 62 | 85 | 50 |
| Number and (%) of countries compliant | 8 (21%) | 47 (46%) | n/a | 11 (16%) | 56 (73%) | n/a | 9 (100%) | n/a | 7 (7%) | 8 (100%) | 30 (58%) | 81 (93%) | 7 (58%) | 6 (7%) | 6 (2%) | 56 (66%) | n/a |
| WHO AQGs | 25 | 50 | None | 100 | 200 | None | 500 | None | 20 | 100 | 35 | 10 | 7 | 20 | 10 | 40 | None |
| WHO Interim target 3 | 37.5 | 75 | None | None | None | None | None | None | None | None | None | None | 30 | 15 | None | None | |
| WHO Interim target 2 | 50 | 100 | None | None | None | None | None | None | 50 | None | None | None | None | 50 | 25 | None | None |
| WHO Interim target 1 | 75 | 150 | None | 160 | None | None | None | None | 125 | None | None | None | None | 70 | 35 | None | None |
Footnote regarding averaging times: 24-h—daily mean, mean of 24-h, 1-h: mean of 1-h values, O3 8-h daily max: daily maximum of running 8-h mean