Christine Merkel

Christine Merkel

Air pollution: the heart of a health crisis

19 September 2017

graphic with layered roads and people walking

Air pollution is a significant contributor to cardiovascular, respiratory and other diseases. And with levels of pollution rising, policymakers must act to safeguard the health of their populations.

Just five days into 2017, one road in London had already exceeded its air pollution limit for the entire year – with many others soon to follow.

In ‘mega cities’ such as Beijing, periods of extreme air pollution lasting weeks are becoming the norm. And, shockingly, 2014 figures revealed 92% of the world’s population was living in places that did not meet the World Health Organization (WHO) air quality guidelines.

Air pollution disproportionately affects developing countries. The WHO announced in 2016 that 98% of cities in low- and middle-income countries did not meet air quality guidelines. In high-income countries, meanwhile, this figure was 56%. Considering the health impacts of air pollution – not to mention wider environmental effects – it is imperative that we act to reduce it.

What is air pollution?

Environmental (also known as ambient) air pollution arises from many sources. Among other things, sources include fossil fuel combustion from cars, coal power plants, and solid fuel burning at home. This pollution is a mix of gases and other particles, each of which can be harmful and affect the body differently. These include particulate matter and gases such as ozone (O3), nitrogen dioxide (NO2) and sulphur dioxide (SO2).

Particulate matter (PM) is a mixture of very small particles and liquid droplets that get into the air. This type of pollution affects people more than any other pollutant. When inhaled, PM can penetrate the lungs and even the vascular system. Negative effects have been noted from both very short-term and long-term exposure.

The smallest type of PM (fine PM of 2.5 microns: PM2.5) has been noted by the WHO to have ‘no threshold… identified below which no damage to health is observed’. PM2.5 alone has been estimated to cause 3.15 million deaths per year – and this is set to double by 2050. The greatest burden occurs across much of Asia and the Pacific. Together, ambient air pollution and tobacco smoking are significant contributors to morbidity and mortality. In the 2015 Global Burden of Disease study, they are the fifth-highest and second-highest risk factors, respectively. I’m not going to delve into ‘personal’ air pollution via tobacco smoking, but it is an avoidable cause of death and disease that directly impacts the health of the smoker and others around them, so could also be argued to contribute to ambient air pollution.

Even short-term exposure to air pollution can increase risk of heart attack, stroke and congestive heart failure.

What are the health impacts of air pollution?

Air pollution causes or aggravates numerous diseases and health issues. Some of the most obvious are those associated with the lungs: asthma, emphysema and chronic bronchitis. But even short-term exposure to air pollution can also increase risk of heart attack, stroke and congestive heart failure. Exposure to air pollution has been linked to higher rates of hospital admission and mortality for heart failure and stroke. This puts a significant burden on healthcare systems, not to mention patients and their families.

Risks are magnified among vulnerable groups – minorities, older people, children and people with pre-existing conditions. For pregnant women, pollutants can negatively affect a foetus and cause long-term health problems including congenital heart defects, obesity and predisposition to cardiovascular disease (CVD). Our knowledge of the impact of air pollution in utero is limited, but it has been shown that the ‘dose’ of pollution experienced by the foetus may be relatively higher than that of the mother.

Medical advances have led to more people surviving cardiovascular events and living with CVD, such as hypertension. This means a vast number of people will be affected if governments do not take action to combat air pollution.

What can be done?

Many people – including healthcare professionals and policymakers – often fail to appreciate the cardiovascular health risks of air pollution. The respiratory effects are easier to identify, but long-term exposure to air pollution can also have serious cardiovascular health implications. Although awareness of CVD is growing, the impacts of pollution are still not widely known.

There is clearly a case for change, from both a health and an environmental perspective. But when it comes to ambient air pollution, policymakers and leaders across a range of sectors have a duty to protect citizens. Even modest improvements and incremental change in air quality can lead to increased life expectancy over short timeframes. Whether it’s by reducing traffic, planning healthier cities and developments, passing anti-smoking legislation or regulating industry, there is much that can be done.

But too few countries meet WHO air quality guidelines and, all too often, there is not enough action at a national level. Air pollution control measures face countless barriers; increasing ‘green’ power infrastructure can be economically and politically challenging. Meanwhile, international treaties and national policies are often ‘toothless’ and end up being ignored. But there can be no doubt that this is a public health priority. Until policymakers act to overcome these obstacles, millions will continue to live in – and be harmed by – increasingly unhealthy environments.


The opinions expressed in this blog are those of the author and do not necessarily represent the views of The Health Policy Partnership.