Table A - Summary of National Air Quality and International Standards, Objectives and Guidelines

Table A. Summary of National Air Quality and International Standards, Objectives and Guidelines
PollutantStandard / Objective / GuidelineAveraging PeriodDate(1)
Nitrogen dioxide (NO2)200 μg m-3 not to be exceeded more than 18 times a year1-hour mean31 December 2005
Nitrogen dioxide40 μg m-3Annual mean31 December 2005
Nitrogen dioxide (NO2)WHO AQG(2): 10 μg m-3Annual mean 
Particles (PM10)50 μg m-3 not to be exceeded more than 35 times a year24-hour mean31 December 2004
Particles (PM10)WHO AQG(2): 45 μg m-3 not to be exceeded more than 3 to 4 times a year24-hour mean 
Particles (PM10)40 μg m-3Annual mean31 December 2004
Particles (PM10)WHO AQG(2): 15 μg m-3Annual mean 
Particles (PM2.5)10 μg m-3(3)Annual mean2040
Particles (PM2.5)London Mayoral Commitment(4): 10 μg m-3Annual mean2030
Particles (PM2.5)WHO AQG(2): 5 μg m-3Annual mean 
Particles (PM2.5)Target of 15% reduction in concentration at urban background locations3-year meanBetween 2010 and 2021
Particles (PM2.5)WHO AQG(2): 15 μg m-324-hour mean 
Sulphur dioxide (SO2)266 μg m-3 not to be exceeded more than 35 times a year15-minute mean31 December 2005
Sulphur dioxide (SO2)350 μg m-3 not to be exceeded more than 24 times a year1-hour mean31 December 2004
Sulphur dioxide (SO2)125 μg m-3 not to be exceeded more than 3 times a year24-hour mean31 December 2004
Sulphur dioxide (SO2)WHO AQG(2): 40 μg m-3 not to be exceeded more than 3 to 4 times a year24-hour mean 

Notes:

(1) Date by which to be achieved by and maintained thereafter
(2) 2021 World Health Organisation Air Quality Guidelines
(3) Environmental Target Regulations under the Environment Act 2021
(4) London Mayoral Commitment