Understanding the Health Impacts of Air Pollution in London

Project Lead

Dr Heather Walton
Science Policy Group, King's College London

The project, commissioned by the Greater London Authority and Transport for London , estimates, for the first time, the mortality burden of long-term exposure to nitrogen dioxide (NO₂) in London, as well as providing  a new mortality burden estimate for fine particulate matter (PM_2.5). The final report was published on 15^th July 2015.

The mortality burden is expressed as life-years lost across the population as a result of deaths in 2010.

This result is also expressed as ‘equivalent deaths at typical ages’, the deaths that would account for the loss of life years if PM_2.5 or NO₂ were the sole cause.  Generally, many different factors contribute to the development of disease and consequent deaths.

The report extends previous work on the mortality burden of PM_2.5 in London (Miller, 2010) to cover effects of short-term exposure to PM_2.5 and NO₂ as well as the economic valuation of short and long-term effects of both pollutants.

Key findings:

• The total mortality burden of anthropogenic PM_2.5 for the year 2010 is estimated to be 52,630 life-years lost, equivalent to 3,537 deaths at typical ages. The estimate for PM_2.5 attributable deaths has decreased from the previous estimate (4,267 deaths in 2008 based on 2006 concentrations) (Miller, 2010) partly due to a decrease in concentrations, to which policy interventions will have contributed, as well as some adjustments to the previous methods and inputs, such as using anthropogenic rather than total PM_2.5.
• Whilst much less certain than for PM_2.5, the total mortality burden of long-term exposure to NO₂ is estimated to be up to 88,113 life-years lost, equivalent to 5,879 deaths at typical ages (assuming the WHO value of up to a 30% overlap between the effects of PM_2.5and NO₂.  Some of this effect may be due to other traffic pollutants.
• If added together, the total mortality burden in 2010 from PM_2.5 and NO₂ is estimated to be as much as 140,743 life-years lost, equivalent to 9,416 deaths at typical ages.
• In 2010, PM_2.5 and NO₂ were associated with approximately 1990 and 420 respiratory hospital admissions respectively, with an additional 740 cardiovascular admissions associated with PM_2.5.
• The estimated economic costs of the above health impacts ranged from £1.4 billion to £3.7 billion.

Outputs from the health report were also included in the progress report on the delivery of the Mayor of London’s Air Quality Strategy.