Air pollution in UK: the public health problem that won’t go awayBMJ 2015; 350 doi: https://doi.org/10.1136/bmj.h2757 (Published 22 May 2015) Cite this as: BMJ 2015;350:h2757
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Revised figures show domestic wood burning to be the UK’s largest single source of PM2.5 emissions, 2.4 times greater than all PM2.5 emissions from traffic. The new information (33% of PM2.5 emissions in 2013-2014 from domestic wood burning, twice the previous estimate of 17%) highlights the extremely misguided nature of current policies.
The European Environment Agency (EEA) estimates that PM2.5 caused 37,800 premature deaths in the UK in 2012 (420,800 lost years of life), compared to 14,100 premature deaths from NO2 pollution (156,900 lost years of life). The EEA’s estimates were based on methods recommended by the World Health Organization (WHO).
Although perhaps somewhat conservative for NO2 (see note below), these values suggest that current EEC requirements do not reflect the true health costs and are diverting attention away from PM2.5, arguably the most health-hazardous air pollutant. High levels of NO2, O3, and SO2 trigger official public health alerts but high levels of PM2.5 result in ‘notifications’. This might create a false sense of security.
Adding to the confusion, PM2.5 levels up to 35 ug/m3 (well above the WHO guideline of 25 ug/m3) are described as ‘low pollution’. Yet in a study with much lower levels (median PM2.5 of 7.3 ug/m3) an increase of just 3 µg/m3 in annual PM2.5 exposure was associated with a 9% increase in deaths from ischemic heart disease and 3-4.5% increases in all deaths. Describing 35 ug/m3 PM2.5 as low pollution could confuse both the public and policymakers about the most practical and cost-effective ways to reduce the considerable health damage from unhealthy air.
The disproportionate amount of PM2.5 pollution from domestic wood burning continues to escape attention. Few people who install wood stoves are likely to understand that a single log-burning stove permitted in smokeless zones emits more PM2.5 per year than 1,000 petrol cars and has estimated health costs in urban areas of thousands of pounds per year.
Contrary to popular belief, domestic wood stoves also increase the risk that the global temperature rise will exceed the 1.5 or 2 degree limit agreed in Paris. The UN Environment Program and the World Meteorological Organization (UNEP/WMO) recommended phasing out log-burning stoves in developed countries to reduce global warming as well as improve health.
Confusion arises because greenhouse gas inventories have traditionally used a 100-year timescale, despite the fact that current levels of emissions are predicted to cause 1.5 degrees of warming within 15 years and 2 degrees within 35 years. Over the critical period between now and when the temperature limit is likely to be exceeded, the methane, carbon monoxide and black carbon emitted by the average wood stove will cause more global warming than heating half a dozen similar homes with an efficient heat pump.
Rectifying misguided diesel policies will not be easy. Wood stoves last much longer than cars. The sooner policymakers recognize the disproportionate contribution of wood stoves to PM2.5 pollution (a tiny minority of UK households using wood stoves emit over twice as much PM2.5 as all the UK’s cars, trucks and buses), recognize the disproportionate health costs – thousands of pounds per wood stove per year – and consequently heed the UNEP/WMO recommendation to phase our log-burning stoves in developed countries, the better it will be for our health and the health of our planet.
References and additional information
1. UKDEFRA, Department for Environment Food & Rural Affairs. Statistics Release: Emissions of air pollutants in the UK, 1970 to 2014. Available at: https://www.gov.uk/government/statistics/emissions-of-air-pollutants, 2015.
2. EEA, European Environment Agency. Air quality in Europe — 2015 report. EEA Report No 5/2015. Available at: http://www.eea.europa.eu/publications/air-quality-in-europe-2015, 2015.
3. Air Quality News. High particle pollution in London and Birmingham. Available at: http://www.airqualitynews.com/2016/01/20/high-particle-pollution-in-lond.... 2016.
4. London Air. Air Quality Bands Health Information http://www.londonair.org.uk/london/asp/airpollutionhealth.asp?HealthPage... (accessed January 2016_. 2016.
5. Crouse, D.L., et al., Risk of Non-accidental and Cardiovascular Mortality in Relation to Long-term Exposure to Low Concentrations of Fine Particulate Matter: A Canadian National-level Cohort Study. Environ Health Perspect, 2012.
6. AAQG. Health experts advise that current wood heater models are too polluting to be allowed. Australian Air Quality Group. Available at: http://woodsmoke.3sc.net/health. 2015.
7. UNEP/WMO, Integrated Assessment of Black Carbon and Tropospheric Ozone. Summary for Decision Makers. UN Environment Program & World Meteorological Organization. http://www.unep.org/dewa/Portals/67/pdf/Black_Carbon.pdf (accessed 13 March 2012). 2011.
8. Howarth, R.W., Methane emissions and climatic warming risk from hydraulic fracturing and shale gas development: implications for policy. Energy and Emissions Control Technologies, 2015: p. 45-53.
9. AAQG. The Most Effective Ways for Individuals to Reduce their Global Warming. Australian Air Quality Group. Available at: http://woodsmoke.3sc.net/ghg. 2014.
10. WHO, HRAPIE project: recommendations for concentration–response functions for cost–benefit analysis of particulate matter, ozone and nitrogen dioxide, 2013, World Health Organisation. Available at: http://www.euro.who.int/en/health-topics/environment-and-health/air-qual....
11. Pope, C.A., 3rd, et al., Lung cancer, cardiopulmonary mortality, and long-term exposure to fine particulate air pollution. JAMA, 2002. 287(9): p. 1132-41.
Note: the EEA estimates were based on the World Health Organization (WHO) recommendation to calculate effects of NO2 for levels above 20 ug/m3. PM2.5-related mortality has group A classification with sufficient data to enable reliable quantification of effects. Long-term mortality from NO2 exposure is classed as group B, because there is more uncertainty about the data used to quantify the effects. For example, no effects of long-term exposure to NO2 were identified for the half million subjects in the American Cancer Society study.
Competing interests: No competing interests
The misguided nature of favourable tax regimes for diesel vehicles was demonstrated by a comprehensive review that concluded: “global warming has been negatively affected, and air pollution has become alarming in many European locations.” Policymakers failed to take account of the serious health effects of PM2.5 air pollution,(known since 1993 when the Six Cities study was published), and the additional global warming from increased NOx, O3 and black carbon emissions.
We continue to make equally misguided mistakes. Emissions from domestic wood burning are increasing in the UK. They accounted for 17% of PM2.5 emissions in 2013, only marginally less than the 18% from all road transport.
The UN Environment Program and the World Meteorological Organization recommended phasing out log-burning stoves in developed countries to reduce global warming as well as dangerous air pollution. Even if the wood is from a sustainable source, methane and black carbon emissions from log-burning stoves cause more global warming than a gas heater or electric heat pump.
There is much concern about the NO2 standard, yet fine particles (PM2.5) are believed to affect more people than any other pollutant, with chronic exposure causing the most deaths from serious disease. The estimate of 29,000 UK deaths from air pollution is for PM2.5 (not NOx) pollution.
Effective policies should aim to achieve the greatest possible reduction in health damage for the available resources. London’s PM2.5 average (15.5 μg/m3) is much higher than the World Health Organization guideline of 10 μg/m3, which is now considered inadequate. An analysis of 268,050 deaths of people living in areas with 10 μg/m3 or less PM2.5 found that, compared with 6 μg/m3, exposure to 10 μg/m3 increases death rates by 3.7%. New studies using high-resolution PM2.5 data generally show larger increases in mortality than COMEAP’s estimate of 0.6% per 1 μg/ m3 additional annual PM2.5 exposure.
PM2.5 pollution also increases the risk of lung diseases, heart attacks, strokes, cancer and even neurological diseases. A recent study found Alzheimer’s increased by 15% for every 1 μg/ m3 increase in annual PM2.5 exposure.
The annual mean concentration of PM10 from wood burning (1.1 μg/ m3) in London is more than 6 times greater than the city-wide reduction of 0.17 μg/m3 predicted from the first two phases of the London Low Emission Zone to reduce PM from traffic. With 17% of PM2.5 emissions from wood burning and 18% from road transport, solving the wood burning problem could generate more benefits for less cost than solving the problem of diesel emissions.
Instead, misguided policies are allowing the problem to get worse. Log-burning stoves permitted in smokeless zones emit more PM2.5 per year than 1,000 petrol cars, with estimated annual health costs of thousands of pounds per stove per year. Buyers often think log-burning stoves are good for the environment, but in reality they create alarming levels of PM2.5 pollution and their methane and black carbon emissions increase the risk of exceeding 2 degrees of global warming.
Dr Gary Fuller studied sources of PM2.5 pollution in the UK, commenting: “Home wood burning needs to be addressed before more people invest in stoves or make open fires a feature in their living rooms.”
BMJ readers and other health professionals need to convey this message to policymakers so that future policies do not repeat the mistakes of the past, but instead use the best and most cost effective ways to minimize the public health damage from air pollution.
1. Cames, M. and E. Helmers, Critical evaluation of the European diesel car boom - global comparison, environmental effects and various national strategies. Environmental Sciences Europe, 2013. 25(1): p. 15.
2. Dockery, D.W., et al., An association between air pollution and mortality in six U.S. cities. N Engl J Med, 1993. 329(24): p. 1753-9.
3. Department for Environment Farming and Rural Affairs, Emissions of air pollutants in the UK 1970 to 2013. Available at: www.gov.uk/government/uploads/system/uploads/attachment_data/file/388195.... . 2014.
4. UNEP/WMO, Integrated Assessment of Black Carbon and Tropospheric Ozone. Summary for Decision Makers. UN Environment Program & World Meteorological Organization. http://www.unep.org/dewa/Portals/67/pdf/Black_Carbon.pdf (accessed 13 March 2012). 2011.
5. AAQG. The Most Effective Ways for Individuals to Reduce their Global Warming. Australian Air Quality Group. Available at: http://woodsmoke.3sc.net/ghg. 2014.
6. American Heart Association. Long-term exposure to air pollution may harm your brain. Available at: http://newsroom.heart.org/news/long-term-exposure-to-air-pollution-may-h.... 2015.
7. Hawkes, N., Air pollution in UK: the public health problem that won’t go away. Vol. 350. 2015.
8. DEFRA. FOI release. Anthropogenic and non anthopogenic PM2.5 estimates for England. Department for Environment, Food & Rural Affairs and Dan Rogerson. Produced by uk-air.defra.gov.uk. Available at: https://www.gov.uk/government/publications/anthropogenic-and-non-anthopo.... 2013.
9. Shi, L., et al., Low-Concentration PM2. 5 and Mortality: Estimating Acute and Chronic Effects in a Population-Based Study. Environmental health perspectives, 2015.
10. COMEAP, Committee on the Medical Effects of Air Pollutants. The mortality effects of long-term exposure to particulate air pollution in the UK. www.gov.uk/government/uploads/system/uploads/attachment_data/file/304641.... 2010.
11. AAQG. Health experts advise that current wood heater models are too polluting to be allowed. Australian Air Quality Group. Available at: http://woodsmoke.3sc.net/health. 2015.
12. Kioumourtzoglou, M., et al., Long-term PM2.5 Exposure and Neurological Hospital Admissions in the Northeastern United States. Environ Health Perspect; http://dx.doi.org/10.1289/ehp.1408973. 2015.
13. Fuller, G.W., et al., Contribution Of Wood Burning To PM10 In London. Atmospheric Environment, 2014.
14. Fuller, G.W., Pollutionwatch: Please don’t keep the home fires burning, in The Guardian. Available at: http://www.theguardian.com/environment/2015/jan/11/pollutionwatch-dont-k....
Competing interests: No competing interests
When catalytic converters and diesel particulate filters require replacement, it is essential that the replacement unit fitted to a vehicle has the ability to perform its functions to the required standards in order to reduce air pollution and the consequent health problems that ensue.
Independent laboratory evidence obtained confirms that some catalytic converters currently being sold in the UK do not meet the EC standards against which they received their original homologation certification.
It is important that the EC and UK regulators (Department for Transport) monitor the performance of replacement emission control equipment to ensure that the products comply with the legally prescribed performance standards against which they obtained their original official approval status.
Competing interests: DISTRIBUTOR OF EMISSION CONTROL EQUIPMENT FOR MOTOR VEHICLES