What does air pollution do to your body? Who is most at risk? What can you do about it? What even is air pollution?

Pulmonologist Marc Sala, MD and associate professor at Northwestern Medicine, is here to break it down.

What is air pollution?

Pollution heavy in combustion products, like wildfire smoke or material burned during manufacturing, is considered especially carcinogenic, Sala said.

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It comes in many forms — wildfire smoke, car exhaust, manufacturing emissions, even the dust inside your own home. It can be local or global. 

Globally, Sala notes, one of the most common causes of Chronic Obstructive Pulmonary Disease (COPD) is biofuel exposure: people cooking indoors, often over coal or an open flame, without proper ventilation. In the U.S., tobacco remains the leading cause.

Let’s start with the lungs

Your lungs have two main jobs: pull oxygen in and push out the carbon dioxide your body makes.

The biggest misconception, Sala says, is that "it's only people with existing lung disease that suffer from air pollution."

When you breathe pollution in, it doesn't simply go in and out. 

"Your lungs are a major vascular bed that absorb things," Sala said, meaning particles can pass into your bloodstream and travel through the body.

The smallest ones do the most damage. Scientists sort particles by size, drawing rough cutoffs at 10 micrometers and 2.5 micrometers. Those under 2.5 reach the deepest parts of the lung, where they interact with blood vessels and get absorbed.

And the harm shows up in two ways: right away, and over a lifetime.

How does it hurt your body?

"Pollution can have both acute and chronic problems for your health," Sala said. 

On a high-ozone day, or when wildfire smoke moves in, people with asthma, COPD or bronchiectasis can have an immediate reaction.

This can be in the form of what Sala calls a bronchospasm: "where you start to cough very aggressively, or it becomes hard to breathe." 

Even healthy lungs can be irritated by high pollution.

(MORE: More than 33 million American kids face unhealthy air, report warns)

Over the long term, the stakes climb. Constant exposure doesn't just aggravate existing disease — it can cause it, especially when exposure starts early in life. 

"Certainly the air we're exposed to now can make us struggle for years to come,” Sala said.

Once it makes it to your bloodstream, pollution drives oxidative stress and inflammation throughout the body. This process is linked to far more than breathing trouble, including potentially higher rates of diabetes, heart disease and cancer, he says. 

What actually helps

For protection, Sala starts with the basics: limit your exposure and run HEPA filters at home, especially during months with more ozone or pollution. 

If you have asthma, COPD or another lung condition, work with your provider on an action plan. Bronchodilators and other medications can offer relief on a bad air day, so when your lungs start acting up, that's a conversation worth having with a pulmonologist.

Keep in mind that sensitivity varies from person to person — the same level of pollution affects people differently, so it helps to know your own threshold.

Content writer Ada Wood enjoys exploring the stories that science and climate teach us about our natural world and how it influences the way we live in it.