Summary of upper exposure limits of the UK National Air Quality Strategy10
| Upper exposure limit or “standard” | ||
|---|---|---|
| Pollutant | Concentration | Measured as |
| Benzene | 5 ppb | Running annual mean |
| 1,3-Butadiene | 1 ppb | Running annual mean |
| Carbon monoxide | 10 ppm (10 000 ppb) | Running 8 h mean |
| Lead | 0.5 μg/m3 | Annual mean |
| Nitrogen dioxide | 150 ppb | 1 h mean |
| 21 ppb | Annual mean | |
| Ozone | 50 ppb | Running 8 h mean |
| Fine particles (PM10) | 50 μg/m3 | Running 24 h mean |
| Sulphur dioxide | 100 ppb | 15 min mean |