# The Air Quality Regulations 1997, Schedule: AIR QUALITY OBJECTIVES


TABLE
Substance
Air Quality Objective levels
Benzene
5 ppb or less, when expressed as a running annual mean
1,3-Butadiene
1 ppb or less, when expressed as a running annual mean
Carbon Monoxide
10 ppm or less, when expressed as a running 8 hour mean
Lead
0.5 micrograms per cubic metre or less, when expressed as an annual mean
Nitrogen Dioxide
150 ppb or less, when expressed as an hourly mean, and 21 ppb or less, when expressed as an annual mean
PM10
50 micrograms per cubic metre or less, when expressed as the 99th percentile of daily maximum running 24 hour means
Sulphur Dioxide
100 ppb or less, when expressed as the 99.9th percentile of 15 minute means

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Source: https://www.legislation.gov.uk/uksi/1997/3043/schedule (the official version)
Page: https://openlegislation.uk/air-quality-regulations-1997/schedule
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.