Air Pollution: A Silent Journey To Your Heart

Air pollution is a serious issue that poses a range of health risks, particularly to the cardiovascular system. The air we breathe contains tiny particles emitted from power plants, industrial factories, and vehicles, which can have detrimental effects on our heart health. These particles, known as particulate matter (PM), can be inhaled and reach the deepest parts of our lungs, where they can irritate receptors and trigger nerves that regulate vital functions such as heart rate and breathing.

Research has linked both short- and long-term exposure to particulate matter with an increased risk of heart attacks, strokes, and other forms of heart disease. Additionally, air pollution has been found to contribute to the development of atherosclerosis, a buildup of plaque in the coronary artery, which can restrict blood flow and increase the likelihood of cardiovascular events.

The impact of air pollution on heart health is a growing concern, with studies suggesting that even relatively low levels of air pollution can increase the risk of heart-related issues. As a result, it is important to recognize the role of air pollution in cardiovascular health and take steps to reduce exposure and improve air quality.

Particulate matter and nitrogen oxides in the air can lead to premature ageing of blood vessels

Particulate matter, or PM, is made up of tiny pieces of solids or liquids in the air. These particles can be composed of sulphate, nitrates, ammonia, sodium chloride, black carbon, mineral dust, or water. The size of particulate matter is generally defined by their aerodynamic diameter, with PM2.5 and PM10 being the most common in regulatory frameworks and relevant for health. PM2.5 refers to fine inhalable particles with diameters that are generally 2.5 micrometres and smaller, while PM10 refers to inhalable particles with diameters of 10 micrometres and smaller. These small particles can be inhaled deeply into the lungs, where they can then affect the heart and blood vessels.

Nitrogen oxides, or NOx, are also of concern when it comes to air pollution and their effects on the cardiovascular system. Nitrogen dioxide (NO2), a reddish-brown gas that is soluble in water, is an important precursor to ground-level ozone, which is closely linked to asthma and other respiratory conditions. Exposure to nitrogen dioxide can irritate the airways and aggravate respiratory diseases.

Long-term exposure to both particulate matter and nitrogen oxides has been linked to premature ageing of blood vessels. A 2016 study published in The Lancet found that exposure to these pollutants at levels close to the National Ambient Air Quality Standards (NAAQS) can prematurely age blood vessels and contribute to a more rapid buildup of calcium in the coronary artery. This buildup of calcium restricts blood flow to the heart and other major blood vessels, increasing the likelihood of cardiovascular events such as heart attacks and strokes. The study also found that the higher the exposure level, the faster atherosclerosis progresses.

The effects of particulate matter and nitrogen oxides on the cardiovascular system are serious and should not be overlooked. It is important to take steps to reduce exposure to these pollutants, such as checking local air quality and staying indoors when the air quality is poor, as well as advocating for policies that address air pollution and protect heart health.

Fine particles in the air can be inhaled deeply into the lungs and affect the heart

These fine particles are the biggest problem when it comes to air pollution because they are the most likely to cause health problems. Their small size allows them to be inhaled deeply into the lungs. Once in the lungs, they can affect the heart and blood vessels. This is why breathing in particle pollution can cause serious problems, such as a heart attack for someone with heart disease.

Research shows that both short- and long-term exposure to particulate pollution are linked to an increased risk of heart attacks and other forms of heart disease. A decade-long study by the EPA found a direct link between air pollution and atherosclerosis, which is a buildup of plaque in the coronary artery that can affect heart health. The study also found that long-term exposure to air pollution can prematurely age blood vessels and contribute to a more rapid buildup of calcium in the coronary artery, restricting blood flow to the heart and increasing the likelihood of cardiovascular events like heart attack and stroke.

The American Heart Association reports that someone dies from cardiovascular disease every 40 seconds in the United States. While doctors often tell their patients to exercise more, eat better, and quit smoking to lower their cardiovascular risk, there are other factors that impact heart health, like air pollution exposure.

Exposure to air pollution can lead to an increased risk of heart attacks

Particulate matter comes in many sizes and shapes and can be made up of hundreds of different chemicals. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small that they can only be detected using an electron microscope. These smaller particles, known as PM2.5, are of particular concern as they are not trapped by the body's natural defences against airborne contaminants. They travel deep down into the lungs, where they irritate receptors and trigger nerves involved in regulating vital functions such as heart rate and breathing.

Research has shown that exposure to increased concentrations of PM2.5 over a few hours to weeks can trigger heart attacks in people with heart disease. Longer-term exposure can lead to an increased risk of cardiovascular mortality and decreased life expectancy. The Multi-Ethnic Study of Atherosclerosis Air Pollution Study (MESA Air) also found that long-term exposure to particulate matter and nitrogen oxides can prematurely age blood vessels and contribute to a more rapid buildup of calcium in the coronary artery, restricting blood flow to the heart and increasing the likelihood of a heart attack.

Overall, while the individual risk of cardiovascular disease from particle pollution is smaller than that of other well-established risk factors, population-level exposure has been shown to increase hospitalizations for serious cardiovascular events, particularly in people with established heart disease.

Air pollution can cause inflammation and accelerate atherosclerosis

Particulate matter (PM) in the air, especially PM2.5 (particles with diameters less than 2.5 microns), can infiltrate deep into the lungs and irritate receptors, triggering nerves involved in regulating vital functions like heart rate and breathing. This can lead to an increased risk of heart rhythm disorders such as atrial fibrillation. PM2.5 can also cause inflammation, with immune system cells and other substances accelerating the buildup of fatty plaque inside the arteries.

Research has found a link between exposure to PM2.5 and the progression of atherosclerosis. For example, a study in Los Angeles found a positive association between long-term exposure to ambient PM2.5 and increased carotid intima-media thickness (CIMT), a measure of subclinical atherosclerosis. Another study in Cleveland, Ohio, showed that long-term exposure to PM2.5 was associated with enhanced progression and vulnerability of atherosclerotic lesions.

The Multi-Ethnic Study of Atherosclerosis Air Pollution Study (MESA Air) also found a direct link between air pollution and atherosclerosis. The study involved collecting and analyzing data on 6,800 diverse participants and the air quality in six regions where they lived. It concluded that there was a direct link between air pollution exposure and plaque buildup, with healthy individuals exposed to air particle pollution over the long term exhibiting accelerated cases of atherosclerosis.

Overall, the evidence suggests that air pollution, particularly PM2.5, can cause inflammation and accelerate atherosclerosis, increasing the risk of cardiovascular events.

Air pollution is linked to an increased risk of stroke

Air pollution is an established risk factor for stroke, with evidence from epidemiological studies demonstrating a strong association between the two. While the relative risk at an individual level is small, air pollution is so ubiquitous that the absolute risk to populations is significant.

A 2015 meta-analysis of 103 observational studies across 28 countries found an association between gaseous pollutants (carbon monoxide, sulphur dioxide, and nitrogen dioxide) and stroke-related hospitalisations or deaths. Both PM2.5 and PM10 particulate matter were also associated with hospitalisations or deaths due to stroke. The Global Burden of Diseases study in 2015 estimated that air pollution accounted for 19% of all cardiovascular deaths, 21% of deaths due to stroke, and 24% of deaths due to ischaemic heart disease.

The adverse health effects of air pollution are particularly pronounced in low- and middle-income countries, where air pollution is projected to rise due to rapid industrialisation. A study in China found indoor coal fumes to be a risk factor for stroke, independent of age, blood pressure, and smoking status.

While the biological mechanisms underlying the link between air pollution and stroke are still under investigation, air pollution is thought to affect the cells lining the circulatory system and increase the activity of the sympathetic nervous system, leading to narrower blood vessels, increased blood pressure, restricted blood supply to tissues, and a higher risk of thrombosis.

Strategies to Reduce Air Pollution Exposure

• Check local air quality and stay indoors when it is poor.
• Use an N95 mask when going outside to filter out fine airborne contaminants.
• Use a portable air cleaner at home, especially if you live in an area affected by wildfire smoke.
• Reduce pollution production by walking, biking, carpooling, or using public transportation.
• Choose renewable energy sources like solar or wind power if possible.

Frequently asked questions