| Pollutant | Standard | Objective - to be achieved by 2005 | Proposals for the amendments to the NAQS objectives | |
| Concentration | Measured as | |||
| Benzene | 5 ppb | running annual mean | 5 ppb | 5 ppb by end 2003, indicative level of 1ppb by end 2005 |
| 1,3-butadiene | 1 ppb | running annual mean | 1 ppb | 1ppb by end 2003 |
| Carbon monoxide | 10 ppm | running 8-hour mean | 10 ppm | 10 ppm by end 2003 |
| Lead | 0.5 mg/m3 | annual mean | 0.5 mg/m3 | 0.5 mg/m3 by end 2004 0.25 mg/m3 by end 2008 |
| Nitrogen dioxide | 150 ppb 21 ppb | 1 hour mean annual mean | 150 ppb 21 ppb | 104.6 ppb by end 2005 (max. 18 exceedences) 21 ppb retained as provisional objective for end 2005 New annual national objective of 15.7 ppb end 2000 |
| Ozone | 50 ppb | running 8-hour mean | 50 ppb, measured as 97th percentile | 50 ppb retained as indicative level for end 2005 |
| Particles (PM10) | 50 mg/m3 | running 24-hour mean | 50 mg/m3 measured as 99th percentile | New annual objective of 40 mg/m3 and 24 hr objective of 50 mg/m3 (max 35 exceedences) for end 2004 50 mg/m3 as 99th percentile of daily max running 24 hr means to be retained as indicative level for end 2005 New indicative annual level of 20 mg/m3 and 24hr level of 50 mg/m3 (max 7 exceedences) for end 2009 |
| Sulphur dioxide | 100 ppb | 15 minute mean | 100 ppb, measured as 99.9th percentile | 100ppb as 99th percentile of 15min means adopted as firm objective for end 2005 New 1hr objective of 131 ppb (max 24 exceedences) and 24 hr objective of 48.6ppb (max 3 exceedences) by end 2004 New national annual and winter objectives, for the protection of eco-systems, of 7ppb for end 2000 |
| ppm = parts per million; ppb = parts per billion; mg/m3 = microgrammes per cubic metre | ||||
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