Recent advances in the understanding of the health impacts of air pollution

Frank Kelly

King’s College London

The case for a national network of low emission zones Coin Street Community Centre, 1st May 2014

Update sources since 2005 WHO guidelines

• 1000’s new health studies, reviews (2006-2014)• NPACT study (2013); ESCAPE (2013)• REVIHAAP (July 2013); HRAPIE (Dec 2013)• HEI Ultrafines report (2013)• WHO Black Carbon report (2012)• IARC Diesel exhaust report (2013)• WHO Burden of disease report (March 2014)

Benefits of improved air quality

Increased volume of evidence Broader range of evidence

Role of fractions

Recent developments in the evidence of the health effects of traffic pollutants – PM2.5 and NO2

As concluded by REVIHAPP• Since WHO 2005 there is additional support for the effects of short-

term exposure to PM2.5 on both mortality and morbidity based on several multicity epidemiologic studies.

• Since WHO 2005 there is additional support for the effects of long-term exposures to PM2.5 on mortality and morbidity based on several studies of long-term exposure conducted on large cohorts in Europe and North America.

• An authoritative review of the evidence for cardiovascular effects, conducted by cardiologists, epidemiologists, toxicologists and other public health experts, concluded that long-term exposure to PM2.5 are a cause of both cardiovascular mortality and morbidity.

Benefits of improved air quality

Increased volume of evidence Broader range of evidence

Role of fractions

Recent developments in the evidence of the health effects of traffic pollutants – PM2.5 and NO2

As concluded by REVIHAPP – PM2.5

• Significantly more insight has been gained into physiological effects and plausible biological mechanisms linking short- and long-term PM2.5 exposure with mortality and morbidity as observed in epidemiological, clinical and toxicological studies;

• Additional studies linking long-term exposure to PM2.5 to several new health outcomes including atherosclerosis, adverse birth outcomes and childhood respiratory disease;

• Emerging evidence also suggests possible links between long-term PM2.5 exposure and neurodevelopment and cognitive function as well as other chronic disease conditions such as diabetes.

As concluded by REVIHAPP – NO2• Many new studies document associations between day-to-day variations

in NO2 concentration and variations in mortality, hospital admissions, and respiratory symptoms.

• Studies have now been published, showing associations between long-term exposure to NO2 and mortality and morbidity.

• Both short- and long-term studies have found these associations with adverse effects at concentrations at or below the current EU limit values.

• The results of these new studies provide support for updating the 2005 global update of the WHO air quality guidelines which could result in lower guideline values.

Benefits of improved air quality

Increased volume of evidence Broader range of evidence

Role of fractions

Recent developments in the evidence of the health effects of traffic pollutants – PM2.5 and NO2

Role of PM fractions

Chemical Composition Physical properties Source types

Transition metals Size• UF• Fine• coarse

Traffic• Carbonaceous material• Traffic-generated dust

Black carbon Particle number Coal combustion

Organic carbon Surface area Industry• Shipping• Power generation• Metal industry

Secondary inorganic aerosols

Biomass combustion

Desert dust

Source types• Road traffic

– Carbonaceous material– Traffic generated dust including road, brake & tyre wear

• Coal combustion• Shipping (oil combustion)• Power generation (oil & coal combustion)• Metal industry (nickel)• Biomass combustion (wood combustion, wild fires)• Desert dust episodes

Traffic is the main source of urban pollution

GlasgowManchester

Summary of air pollution related health effects- epidemiology evidence synthesis -

Health outcome Association with traffic air pollution exposure

MortalityAll-cause & CV Sufficient

Asthma & Respiratory – childrenAsthma onset & prevalence

Asthma is more common in children living in the street buffers with the highest concentration of traffic-related pollutants

Exacerbation of asthma symptomsChildren living in hot spots of traffic-related pollution experience more symptoms and exacerbations

Sufficient

Sufficient

Asthma & Respiratory – AdultsAdult onset of asthma (one study)Exacerbation of asthma symptoms (few studies)Hospitalisation rates

InsufficientSuggestive but not sufficient

Insufficient

Lung functionLiving in proximity to high concentration of traffic air pollution may be associated with reduced lung function

Suggestive but not sufficient

Benefits of improved air quality

Increased volume of evidence Broader range of evidence

Role of fractions

Recent developments in the evidence of the health effects of traffic pollutants – PM2.5 and NO2

Improvements in PM10 (& PM2.5) reduces respiratory symptoms

SAPALDIA Study, Schindler et al, 2009

New CoughPersistent Cough

New WheezePersistent Wheeze

THANK YOU FOR YOUR ATTENTION!

PM2.5 air pollution & life expectancy in the US

Pope et al, 2009

Reduction in PM2.5, 1980-2000 (μg/m3)

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REVIHAAP – Question C2

Is there any new evidence on the health effects of NO2 that impact upon the current limit values? Are long-term or short-term limit values justified on the grounds that NO2 affects human health directly, or is it linked to other co-emitted pollutants for which NO2 is an indicator substance?

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10 years of air quality guidelines

Particulate matter (PM)Nitrogen dioxide (NO2)Ozone (O3)

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• resulted in the equivalent of 29,000 deaths due to breathing tiny particles released into the air (in 2008)

• the average loss of life was 11.5 years, (although the actual amount varies between individuals)

Published December 2010

Across the UK poor air quality......