New paper finds no association between air pollution and heart attacks

A new paper published in The British Medical Journal Heart finds "no clear evidence for pollution effects on heart attacks and stroke, though it did for pulmonary embolism." The study was one of the largest of its kind and analyzed over 2 million cardiovascular events in England and Wales.

The study analyzed actual air pollutants such as carbon monoxide (CO), nitrogen dioxide (NO2), particulate matter, sulfur dioxide (SO2), and ozone (O3). Note CO2 was not studied for associations since, despite the claims of President Obama and EPA administrator McCarthy, CO2 is not "carbon pollution" and does not have any association with heart attacks, asthma, or any other public health effects. 

Heart doi:10.1136/heartjnl-2013-304963

• Cardiac risk factors and prevention

• Original article

Short-term effects of air pollution on a range of cardiovascular events in England and Wales: case-crossover analysis of the MINAP database, hospital admissions and mortality

1. Ai Milojevic1, 
2. Paul Wilkinson1, 
3. Ben Armstrong1, 
4. Krishnan Bhaskaran2, 
5. Liam Smeeth2,
6. Shakoor Hajat1

+Author Affiliations

1. ¹Department of Social and Environmental Health Research, London School of Hygiene and Tropical Medicine, London, UK
2. ²Department of Non-Communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK

1. Correspondence toDr Ai Milojevic, Department of Social and Environmental Health Research, London School of Hygiene & Tropical Medicine, 15-17 Tavistock Place, London, WC1H 9SH, UK;ai.milojevic@lshtm.ac.uk

• Received 13 September 2013
• Revised 21 February 2014
• Accepted 16 March 2014
• Published Online First 4 June 2014

Abstract

Objective To inform potential pathophysiological mechanisms of air pollution effects on cardiovascular disease (CVD), we investigated short-term associations between ambient air pollution and a range of cardiovascular events from three national databases in England and Wales.

Methods Using a time-stratified case-crossover design, over 400 000 myocardial infarction (MI) events from the Myocardial Ischaemia National Audit Project (MINAP) database, over 2 million CVD emergency hospital admissions and over 600 000 CVD deaths were linked with daily mean concentrations of carbon monoxide (CO), nitrogen dioxide (NO₂), particulate matter less than 10 μm in aerodynamic diameter (PM₁₀), particulate matter less than 2.5 μm in aerodynamic diameter (PM_2.5) and sulfur dioxide (SO₂), and daily maximum of 8-hourly running mean of O₃ measured at the nearest air pollution monitoring site to the place of residence. Pollutant effects were modelled using lags up to 4 days and adjusted for ambient temperature and day of week.

Results For mortality, no CVD outcome analysed was clearly associated with any pollutant, except for PM_2.5 with arrhythmias, atrial fibrillation and pulmonary embolism. With hospital admissions, only NO₂ was associated with a raised risk: CVD 1.7% (95% CI 0.9 to 2.6), non-MI CVD 2.0% (1.1 to 2.9), arrhythmias 2.9% (0.6 to 5.2), atrial fibrillation 2.8% (0.3 to 5.4) and heart failure 4.4% (2.0 to 6.8) for a 10th–90th centile increase. With MINAP, only NO₂ was associated with an increased risk of MI, which was specific to non-ST-elevation myocardial infarction (non-STEMIs): 3.6% (95% CI 0.4 to 6.9).

Conclusions This study found no clear evidence for pollution effects on STEMIs and stroke, which ultimately represent thrombogenic processes, though it did for pulmonary embolism. The strongest associations with air pollution were observed with selected non-MI outcomes.