Do you know Stroke is the second leading cause of 6.6 million deaths annually? Moreover, it also contributes majorly to the disabilities as of 5.7% of total disability-adjusted life years (DALYs) lost globally. Usually, stroke occurs due to several factors including high blood pressure, diabetes, smoking and other factors. But recently, an eye-opening study has confirmed that exposure to air pollution and stroke risk have connections. According to a study published in Global Burden of Disease, air pollution ranked as the fourth leading risk factor for stroke-related deaths and disabilities. 

Air pollution is not just limited to lung or breathing problems. This silent killer is taking millions of lives each year and still, certain conditions are hidden. You cannot imagine how air pollution can affect your body in which way. This study published in Current Opinion on Neurology highlights the connection between air pollution and stroke. Here let us read more to understand how both have connections and can impact human health in which terms. 

How Air Quality Affects Your Body & Increases Stroke Risk?

Air pollution includes various pollutants such as PM10, PM2.5, PM1 and ultrafine particles. Besides, it also includes some harmful gases such as nitrogen dioxide (NO2), ozone (O3), sulfur dioxide (SO2), and carbon monoxide (CO). These pollutants can become the major contributors to stroke and related conditions. 

air polluants and gases responsible for the stroke

1. Particulate Matter: 

Particulate Matter includes tiny particles that can easily get deep into your lungs and even into your bloodstream. It means they have largely damaged the blood vessels and made them narrow and stiff. And in this condition, it blocks the blood flow to the brain which can result in forming clots and strokes. 

  • Another study found that stroke patients exposed to PM2.5 were more likely to die from stroke complications. 

2. Nitrogen Dioxide (NO2):

NO2 in the air is emitted from Various sources including vehicle emissions, factories and others. The exposure can damage the blood vessels and affect the function of blood flow in the body. In a result, the exposed person can face an increase in blood pressure and stroke.

  • Another study showed that people exposed to high NO₂ levels were more likely to have a second stroke after their first one.

3. Ozone (O3):

Ozone can form due to many sources as cars and factories’ emission reacts with the sunlight. And it can result in damage of the blood vessels lining and make them weak which can result in stroke faster.

4. Sulfur Dioxide (SO2):

Sources like factories, power plant emission or coal burning emits SO2 in the air. Inhaling SO2 can affect the blood vessels health as tightening them and affects the blood flow to the brain. It can also result in severe inflammation and increase the stroke risks. 

  • A study found that even a tiny increase in SO₂ levels increased stroke risk by 17%.

5. Carbon Monoxide (CO):

Vehicle emissions, cigarette smoke, and gas stoves can emit CO in the environment. Inhaling CO can affect the oxygen supply to the brain through the blood and can damage the brain cells. It increases the chances of silent strokes due to blood thickness. 

  • A study showed that even a small amount of CO exposure increased stroke risk by 26%.

Do you know according to the study, strokes have around $720 (0.66% of the global GDP) billion annually in global economic cost?

The Study

Here understand the biological mechanisms of how air pollution can trigger the problem:

biological mechanisms of air pollution causing stroke

a. Inflammation and Blood Vessel Damage

Breathing polluted air can cause swelling in the lungs. This swelling then spreads through the body, damaging blood vessels and making arteries tighter. As a result, this increases the risk of heart problems and stroke.

b. Higher Risk of Blood Clots

Pollution can make the blood thicker and more likely to form clots. If a clot blocks an artery, it can stop blood from reaching the brain, causing a stroke.

c. Pollution Can Harm the Brain

Tiny pollution particles can enter the blood and travel to the brain. This can damage brain cells and increase the risk of stroke. Some studies show pollution may even affect memory and thinking.

d. Heart and Blood Pressure Problems

Breathing polluted air for a long time can make the heart beat unevenly and raise blood pressure. This makes heart disease worse and increases the chance of a stroke.

 Air Pollution and Stroke Risk: What the Research Shows

Long-Term Exposure Increases Stroke Risk

  • A study of 30 million people in the U.S. found that for every 1 µg/m³ increase in PM2.5, the risk of stroke went up by 2.79%.
  • A study in Denmark with 2 million people showed that a 5 µg/m³ rise in PM2.5 increased stroke risk by 22.3%.
  • Research in China found that exposure to NO₂ and O₃ also raises the chances of having a stroke.

Short-Term Exposure Can Trigger Strokes Quickly

  • A review of 18 million stroke cases found that stroke risk rises within hours of pollution exposure:
    • PM2.5: 15% higher risk per 10 µg/m³ increase
    • NO₂: 30% higher risk per 10 ppb increase
    • CO: 26% higher risk per 1 ppm increase
  • Visits to the emergency room for stroke increase within just 2 hours of exposure to PM2.5, PM10, NO₂, and SO₂.

Air Pollution Makes Stroke Outcomes Worse

  • A study of 3 million stroke patients in China found that exposure to PM2.5 increased the risk of death by 15.8% for ischemic strokes and 8.2% for hemorrhagic strokes.
  • Furthermore, In Sichuan, China, a study of 1 million stroke patients found that those exposed to higher pollution levels were more likely to be readmitted to the hospital within 30 days.
  • Lastly, A UK study of 370,000 people found that long-term exposure to air pollution sped up the progression from a first stroke to heart disease and, eventually, death.

How to Reduce the Impact of Air Pollution on Stroke Risk?

What Governments Can Do

  • Reduce pollution from traffic and factories to lower exposure.
  • Enforce stricter air quality laws to decrease stroke cases.

What Individuals Can Do

  • Use air purifiers at home and stay indoors on high-pollution days.
  • Wear high-quality masks (N95 or better) in polluted areas.

The Role of Green Spaces

  • Living near parks and trees can help reduce some harmful effects of air pollution and lower stroke risk.

Why This Matters

The science is clear that air pollution is a major cause of strokes. But unlike ageing or genetics, we can control pollution levels through laws and personal actions. Reducing air pollution won’t just prevent strokes but will also improve heart and lung health and save lives.