Heart disease patients have been advised to avoid being outside during rush hour traffic in a paper published in the European Heart Journal. The position paper on air pollution and cardiovascular disease was written by experts from the European Society of Cardiology and also calls for decreasing the use of fossil fuels.
More than 3 million deaths worldwide are caused by air pollution each year. According to the 2010 Global Burden of Disease Study, air pollution ranks ninth among the modifiable disease risk factors, ahead of low physical activity, high sodium diet, high cholesterol and drug use.
In 2004, the American Heart Association (AHA) issued a scientific statement concluding that exposure to air pollution contributes to cardiovascular illness and mortality. A 2010 update elaborated on those risks. Short-term exposure can increase the risk of heart attack, stroke, arrhythmias and heart failure in susceptible people, such as the elderly or those with pre-existing medical conditions, according to the statement.
“There is now ample evidence that air pollution is associated with cardiovascular morbidity and mortality. It not only makes existing heart conditions worse but also contributes to development of the disease,” says Dr. Robert F. Storey, corresponding author of the paper.
“Avoiding air pollution where possible may help to reduce cardiovascular risk and cardiologists should incorporate this information into lifestyle advice for their patients. We also need to increase pressure on policy makers to reduce levels of air pollution,” he adds.
Effects of pollution on cardiovascular health
Up to one-third of Europeans who live in urban areas are exposed to air pollution levels above European Union (EU) standards. But using the more stringent science-based criteria from the World Health Organization (WHO), around 90% of Europeans are exposed to levels that are damaging to health. The U.S. is in no better shape; according to the State of the Air 2014, half of Americans live in areas where pollution levels are often too dangerous to breathe, an increase from the previous year’s report.
Medical researchers are particularly concerned about pollution particles smaller than 2.5 microns, which are usually related to fuel combustion. Because they are so tiny, they aren’t easily screened and more readily enter the human body. They then begin to irritate the lungs and blood vessels around the heart. Current science suggests that over time pollutants aggravate or increase the process of disease in the arteries.
Ground-level ozone, known for years to worsen lung disease, may also trigger heart attacks and strokes in susceptible people. It is formed when pollutant gases emitted by cars and trucks, power plants, industrial boilers, refineries, chemical plants, and other sources react chemically in the presence of sunlight and heat.
The paper recommends the following actions to reduce exposure to air pollution:
- Travel by walking, cycling, and public transportation in preference to car or motorbike
- Avoid inefficient burning of biomass for domestic heating
- Avoid walking and cycling in streets with high traffic intensity, particularly during rush hour traffic
- Exercise in parks and gardens, but avoid major traffic roads
- Limit time spent outdoors during highly polluted periods, especially infants, elderly, and those with cardiorespiratory disorders
- Consider ventilation systems with filtration for homes in high pollution areas.
People with or at high risk of cardiovascular disease are particularly urged to follow this advice. They should also ensure that they take their prescribed medication for primary or secondary prevention of cardiovascular disease, which will help to combat the potential effects of air pollution exposure.
Air pollution as a modifiable risk factor for disease
The authors explain that there is a two way interaction between air pollution and cardiovascular risk factors. For instance, obese people and those with diabetes are thought to be at higher risk of the cardiovascular effects of pollution, while air pollutants appear to exacerbate and instigate the development of risk factors such as high blood pressure and impaired insulin sensitivity.
“The public health implications that air pollution might be a ubiquitous environmental risk factor for hypertension and diabetes are enormous,” the authors write, noting that as a modifiable risk factor, reducing air pollution could yield remarkable health benefits.
They also warn that the role of indoor air pollution should not be downplayed. Past research demonstrates that outdoor air pollution infiltrates buildings and that much exposure actually occurs indoors. “Indoor air quality in homes, schools, working places and community sites is not a trivial problem in Europe,” they note.
The authors point out that fossil fuels are a major source of air pollution and the major source of greenhouse gases, which are fueling climate change and its related effects. This is particularly dangerous for those already at risk of disease, as the interaction of climate change and air pollution could be even more deadly than either on its own.
For example, studies suggest that hot and cold weather extremes may increase the risk of heart attacks or death related to heart attacks. Weather extremes and high pollution sometimes occur together and may be particularly dangerous for those at risk.
Shifting away from the use of fossil fuels for energy production will result in major benefits to human health, the authors say, “both from reduced exposure to air pollution and from mitigation of climate change.”
“Policy makers have an important role to reduce outdoor pollution in order to limit indoor pollution where much of the exposure occurs,” says Dr. Storey. “Apart from reducing their personal contributions to outdoor pollution, there is not much that individuals can do about this unless they invest in systems to filter the air they breathe indoors.”
The paper adds that planning authorities should be encouraged or required to incentivize housing developments that are a reasonable distance from heavily congested roads and polluting industries.
“Air pollution should be considered one of the major modifiable risk factors to prevent and manage cardiovascular disease,” says Dr. Storey. “Individuals, especially those with or at risk of cardiovascular disease, can take measures to reduce their exposure and doctors should include these in lifestyle advice. Policy makers urgently need to reduce levels of air pollution and this should be backed up by legislation.”