Quick guide to air pollution

Known health and other impacts of air pollution have risen much faster than levels of air pollution have fallen

1.      How bad is air pollution in London?

  • London has the highest levels of nitrogen dioxide (NO2) pollution of any capital city in Europe.  Concentrations of dangerous airborne particles (PM10) also breach legal limits in several parts of the city particularly near waste management sites.
  • Government estimates that some 440,439 Londoners were exposed to unlawful levels of NO2 in 2011 at background locations alone i.e. away from busy roads.
  • London’s residents are not the only ones affected by poor air quality.  Every day hundreds of thousands of people commute into the polluted heart of London.  NO2 concentrations are well over twice legal limits and World Health Organisation (WHO) guidelines near many London roadside monitoring sites.  NO2 limits are also breached at a larger number of city centre ‘background’ sites away from busy roads.

2.      What are the health impacts of air pollution in London?

  • Air pollution comprises particles and gases.  The particles are categorised by their maximum diameter in microns e.g. PM2.5 and PM10.  In practice, nitrogen dioxide (NO2), a toxic gas, is the only molecule within the gas category with relevant WHO guidelines and legal limits.
  • Poor air quality has a significant impact on the health of London residents.  The Mayor published a study in 2010 estimating 4,267 premature deaths in London in 2008 attributable to long term exposure to fine particles (PM2.5).  These occur mostly as heart attacks and strokes.  The Department of Health estimates 6.3% to 9.0% of all deaths in London in 2010 were attributable to long-term exposure to man-made PM2.5 alone.
  • Children, the elderly and people with existing respiratory illness suffer disproportionately from the effects of air pollution.  Over 1,100 schools in London are within 150 metres of the city’s busiest and most polluted roads (i.e. those that carry over 10,000 vehicles a day).  Traffic pollution from such roads may be responsible for 15-30% of all new cases of asthma in children and chronic obstructive pulmonary disease in adults of 65 years of age and older.

3.      Are there air pollution standards that London should be meeting?

  • Legally binding, health based limit values have been set for several air pollutants by the European Union since 1999.  London is failing to meet these for PM10 and NO2.
  • For PM10 London was required to meet limit values by 2005 but obtained unlawfully a time extension in 2011 to comply that year.  That time extension has now expired but London has continued to exceed PM10 limits known as ‘Bad Air Days’ particularly near waste management sites e.g. Neasden Lane in Brent.
  • NO2 limits were required to be met by 2010.  The Government has admitted they are not expected to be met in London before 2025 and has been caught seeking to weaken NO2 laws.
  • The Commission is expected to commence infraction action against the UK early in 2013.
  • Useful generic background, resources and links for those involved in planning issues in London (and elsewhere) https://cleanair.london/indoor-air-quality/eight-wins-for-clean-air-in-london-in-new-london-plan/

4.      What are the authorities doing to reduce air pollution in London?

The Mayor of London’s Air Quality Strategy is not ‘fit for purpose’.  The Mayor has also used Pollution Suppressor vehicles to reduce air pollution near air quality monitoring stations most-used to report legal breaches and warn the public of smog episodes.  The Mayor has also been caught lobbying to weaken international air pollution laws.

Diesel engine exhaust, recently classified by the World Health Organisation as carcinogenic to humans, is a particular problem in London which has: some 8,500 diesel buses; over 20,000 diesel taxis; and a low emission zone that is two steps and two years behind the equivalent in Berlin.  A ground breaking study by Policy Exchange found that diesel vehicles are responsible for 95% of NO2 and 91% of PM2.5 exhaust emissions respectively from road transport in London.

The Government has not published a press release warning of smog since April 2011 when it made headline news.  The Mayor also refuses to issue public warnings of smog even though Murad Qureshi AM discovered that hundreds of additional people in London have been admitted to hospital during smog episodes in the last five years alone.

5.      Supporting guides, links and contacts


Health:              ‘Invisible’ air pollution: the biggest public health failing or ‘cover-up’ for decades

Legal:               UK is cheating on air quality laws and misleading the European Commission

Sources:            London has the highest levels of NO2 of any capital city in Europe

Solutions:          Manifesto for the Mayoral and London Assembly elections in 2012

Indoor:              Indoor air quality can be worse than outdoor

Pollutant Legal standard World Health Organisation guideline
  Short term Annual mean Short term Annual mean
Fine particulate matter (PM2.5)
  1. 25 ug/m3 annual mean to become limit value in 2015
  2. 20 ug/m3 exposure concentration obligation based on a 3-year average by 2015
  3. Exposure reduction target in percentage by 2020
25 ug/m324-hour mean 10 ug/m3
Particulate matter (PM10) 35 days over 50 ug/m3 since 2011 40 ug/m3since 2011 50 ug/m324-hour mean 20 ug/m3
Ozone (O3) 25 days over 120 ug/m3 maximum daily 8-hour mean target value averaged over 3 year since 2010   100 ug/m3 8-hour mean  
Nitrogen dioxide (NO2) 18 hours over 200 ug/m3 since 2010 40 ug/m3 since 2010 200 ug/m3 40 ug/m3

Note: ug/m3 is micrograms per cubic metre

Examples of legal breaches in 2012

London Air Quality Network:     Marylebone Road

                                          Neasden Lane

                                          Putney High Street

Smog episodes

London Air Quality Network:     Latest hourly bulletin

London Air Quality Network:     Health advice

London Air Quality Network:     Reports on smog episodes

Defra website:                          UK-Air: Air Information Resource (selective monitoring)

Article from The Independent newspaper on the effects of air pollution on athletes, quoting air pollution and health expert Professor Frank Kelly (Kings College, London)

LBC Radio 97.3 news on 27 February 2013


CAL 186 Quick guide 220612

CAL 221 EEB Agenda_Air conference 080113

CAL 230 NGO joint position paper with logos 050313

CAL 258 MAQS_Sources of PM

CAL 256 UK AQ Zones and AQ as reported September 2013_Updated draft 311213

Contact Clean Air in London




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