Short-term exposure to air pollution increases stroke risk

Recent research indicates that even short-term exposure to air pollution could significantly increase the risk of stroke. 

This revelation comes from a comprehensive meta-analysis published by the American Academy of Neurology. 

Short-term exposure 

The study defines “short-term exposure” as any exposure occurring within five days prior to the stroke event.

“Previous research has established a connection between long-term exposure to air pollution and an increased risk of stroke. However, the correlation between short-term exposure to air pollution and stroke had been less clear,” said study lead author Dr. Ahmad Toubasi from the University of Jordan. 

“For our study, instead of looking at weeks or months of exposure, we looked at just five days and found a link between short-term exposure to air pollution and an increased risk of stroke.”

Focus of the study 

The experts reviewed 110 distinct studies, which collectively involved more than 18 million stroke cases. Key pollutants such as nitrogen dioxide, ozone, carbon monoxide, and sulfur dioxide were the primary focus. 

Furthermore, the researchers investigated the different sizes of particulate matter present in the air. This included PM1, particles that are less than 1 micron (μm) in diameter; PM2.5, minute inhalable particles emanating from vehicle exhaust, industrial fuel burning, and natural fires; and PM10, which captures dust from roads and construction sites.

Increased stroke risks

The results of the study showed that exposure to elevated concentrations of these pollutants was directly associated with an increased stroke risk.

• Nitrogen dioxide: 28% increased risk
• Ozone: 5% increased risk
• Carbon monoxide: 26% increased risk
• Sulfur dioxide: 15% increased risk
• PM1: 9% increased risk
• PM2.5: 15% increased risk
• PM10: 14% increased risk

These pollutants were also associated with a higher risk of death from stroke, with nitrogen dioxide leading to a 33% increased risk and sulfur dioxide resulting in a 60% increase.

“There is a strong and significant association between air pollution and the occurrence of stroke as well as death from stroke within five days of exposure,” said Dr. Toubasi.

“This highlights the importance of global efforts to create policies that reduce air pollution. Doing so may reduce the number of strokes and their consequences.”

Air pollution and cardiovascular health

Air pollution is known to have extremely detrimental impacts on health, particularly the cardiovascular system. 

Heart attacks

Air pollution is associated with a higher incidence of heart attacks. Particulate matter and toxic gases in polluted air can accelerate the formation of plaque in the arteries, leading to atherosclerosis, which increases the risk of heart attacks.

Stroke

As found in the meta-analysis published in Neurology®, short-term exposure to air pollution has been linked to an increased risk of strokes. The pollutants can cause inflammation and oxidative stress, leading to changes in the arteries that supply blood to the brain.

Hypertension

Studies have shown that exposure to air pollution can result in elevated blood pressure levels. Pollutants may cause the blood vessels to constrict, leading to hypertension, a significant risk factor for cardiovascular diseases.

Heart failure

There is evidence that air pollution can exacerbate heart failure, where the heart doesn’t pump blood as well as it should. The pollutants can lead to inflammation, affecting the heart’s functionality and worsening pre-existing conditions.

Arrhythmias

Exposure to air pollution has been linked with irregular heartbeats (arrhythmias). Particulates and other pollutants can affect the heart’s electrical activity, leading to arrhythmias, which can be dangerous if not managed.

Deep vein thrombosis

Research has found correlations between exposure to high levels of air pollution and an increased risk of developing DVT, a condition where blood clots form in veins deep in the body, usually in the legs.

Long-term effects

Chronic exposure to air pollution over the years can lead to persistent inflammation and stress on the cardiovascular system, resulting in long-term damage and an increased risk of cardiovascular diseases.

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