• Asthma
• Bronchitis
• Chest Congestion

How Does Air Pollution Affect Lung Health?

Published: May 30, 2025
Updated: June 01, 2025
4 mins

Air pollution has become an increasingly urgent public health issue in the U.S., with more days of poor air quality reported across major cities and rural communities alike. From vehicle emissions to wildfire smoke, the sources of pollution are widespread – and their effects are not limited to the environment. 

Growing evidence shows that air pollution is affecting health in ways both immediate and long-term. Whether it’s triggering asthma, contributing to heart disease, or increasing the risk of lung cancer, polluted air carries serious health consequences. 

Understanding the health impacts of air pollution isn’t just important for people with preexisting conditions – it’s essential for anyone who breathes. 

What Causes Air Pollution?

Air pollution stems from a wide range of human activities and natural events that release harmful substances into the air. In the U.S., several key sources contribute to the ongoing problem:

Vehicle emissions

Cars, trucks, and buses are among the biggest contributors to air pollution, especially in densely populated urban areas and along major highways. Tailpipe emissions release nitrogen dioxide (NO₂), carbon monoxide (CO), and particulate matter – all of which have been directly linked to adverse health outcomes.

Industrial processes and power plants

Factories, oil refineries, and coal- or gas-burning power plants emit large amounts of pollutants, including sulfur dioxide (SO₂), volatile organic compounds (VOCs), and heavy metals. These emissions not only degrade air quality but also contribute to the formation of ground-level ozone and smog.

Construction and agriculture

Dust from construction sites, diesel-powered equipment, fertilizer use, and livestock waste all contribute to air pollution. Agricultural practices in particular can release ammonia and methane, which affect both air quality and climate.

Wildfires and wood burning

The increasing frequency and severity of wildfires in the U.S. has become a major source of fine particulate matter (PM2.5), which can travel hundreds of miles and linger in the air for days. Wood-burning stoves and fireplaces also add to indoor and outdoor pollution levels, especially in colder months.

Household products

Common items like cleaning sprays, paint, and air fresheners release VOCs that contribute to indoor air pollution and the formation of ozone when they react with sunlight outdoors.

The Most Harmful Air Pollutants

When we talk about the health effects of air pollution, we're often referring to specific harmful substances that can be inhaled and absorbed into the body. Many of these pollutants not only irritate the lungs but also enter the bloodstream, triggering a wide range of systemic health risks.

Particulate matter (PM2.5 and PM10)

These tiny airborne particles – PM10 being coarse and PM2.5 fine enough to enter the bloodstream – are among the most dangerous pollutants. Generated by vehicles, wildfires, and industrial processes, they can penetrate deep into the lungs, causing inflammation, oxidative stress, and exacerbating conditions like asthma, COPD, and heart disease. Long-term exposure to PM2.5 has also been linked to lung cancer and cognitive decline.

Nitrogen dioxide (NO₂)

Primarily produced by vehicle emissions and power plants, NO₂ is a reactive gas that irritates the airways and reduces lung function. Inhaling NO₂ can worsen asthma and increase susceptibility to respiratory infections. It also contributes to the formation of ground-level ozone and secondary particles, compounding its health impacts.

Ozone (O₃)

Unlike the protective ozone layer high in the atmosphere, ground-level ozone is a harmful pollutant formed when sunlight reacts with NOx and VOCs. Breathing ozone can lead to shortness of breath, chest pain, and throat irritation. It’s especially dangerous for people with asthma or other chronic lung conditions. Over time, it can cause permanent lung damage and reduced lung capacity.

Sulfur dioxide (SO₂)

A byproduct of burning fossil fuels (especially coal), SO₂ can irritate the respiratory tract almost immediately upon inhalation. It triggers bronchoconstriction, making it difficult to breathe – especially for those with asthma. SO₂ also reacts in the atmosphere to form fine particulate pollution (secondary PM), compounding its harmful effects.

Carbon monoxide (CO)

This colorless, odorless gas is released from car exhaust, wildfires, and inefficient home heating systems. When inhaled, CO binds to hemoglobin more readily than oxygen, reducing the blood’s ability to transport oxygen throughout the body. This can lead to fatigue, dizziness, impaired cognition, and, in high exposures, death. People with heart disease are especially vulnerable to CO’s systemic effects.

Volatile organic compounds (VOCs)

Found in paints, cleaning products, fuel, and emissions, VOCs are a broad category of chemicals that easily become vapors or gases. When inhaled, VOCs can irritate the eyes, nose, and throat, and some may cause headaches, nausea, or liver and kidney damage. Chronic exposure is associated with certain cancers and nervous system effects. VOCs also contribute to ozone formation, worsening outdoor air quality.

Benzene and formaldehyde

These specific VOCs are particularly toxic. Benzene, found in vehicle exhaust and tobacco smoke, is a known human carcinogen linked to leukemia. Formaldehyde, used in building materials and household products, can cause throat and nasal irritation, trigger asthma, and has also been classified as a probable human carcinogen. Both substances pose dangers not just through breathing but also through prolonged, low-level indoor exposure.

Health Effects of Air Pollution

Air pollution doesn't just irritate the lungs – it affects nearly every system in the body. Exposure to polluted air, even at low levels, can lead to a range of short- and long-term health consequences, with some effects appearing within hours and others developing after years of exposure.

Breathing problems, eye irritation, and fatigue

Short-term exposure to pollutants like ozone and fine particulate matter (PM2.5) can cause coughing, wheezing, throat irritation, and eye discomfort. Many people also experience fatigue or headaches when air quality is poor, even if they don’t have underlying conditions.

Increased risk of cardiovascular disease

Polluted air doesn’t stop at the lungs – it enters the bloodstream and affects the heart. Studies have linked long-term exposure to air pollution with high blood pressure, increased risk of stroke, heart attacks, and the development or worsening of heart disease.

Impaired immune function

Certain pollutants can weaken the immune system, making the body more vulnerable to infections. Chronic inflammation caused by airborne toxins may also contribute to autoimmune conditions and reduce the body’s ability to recover from illness.

Developmental effects in children

Children are particularly vulnerable to air pollution due to their developing lungs and higher respiratory rates. Exposure during pregnancy and early childhood has been associated with lower birth weights, impaired lung growth, and higher risks of asthma and neurodevelopmental delays.

Cognitive decline in older adults

Emerging research has drawn a strong connection between long-term exposure to air pollution and cognitive decline. Older adults exposed to high levels of pollution may face an increased risk of dementia, including Alzheimer’s disease, as well as more rapid loss of memory and mental processing.

Lung Diseases Linked to Air Pollution

When it comes to the health impacts of air pollution, the lungs are often the first to suffer. Breathing in pollutants day after day can irritate airways, damage lung tissue, and worsen existing conditions. Over time, this exposure can also lead to the development of serious respiratory diseases.

Asthma

Air pollution is a well-known trigger for asthma attacks. Ozone, particulate matter, and nitrogen dioxide can inflame the airways, making it harder to breathe. Children and adults with asthma often experience more frequent and severe symptoms on days with poor air quality.

Chronic obstructive pulmonary disease (COPD)

COPD – which includes conditions like chronic bronchitis and emphysema – is worsened by long-term exposure to polluted air. Inhaling harmful particles and gases causes inflammation, narrows the airways, and can accelerate lung function decline, especially in smokers and older adults.

Bronchitis

Pollutants like sulfur dioxide and particulate matter can irritate the lining of the bronchial tubes, leading to both acute and chronic bronchitis. Symptoms include coughing, chest tightness, and increased mucus production – especially during pollution spikes.

Emphysema

A subtype of COPD, emphysema is marked by damage to the air sacs in the lungs. Air pollution, particularly fine particulate matter (PM2.5), can speed up this damage, reducing the lungs' ability to bring in oxygen and expel carbon dioxide.

Lung cancer

The connection between air pollution and lung cancer is well-established. Long-term exposure to PM2.5 – tiny particles that can penetrate deep into the lungs – has been shown to increase the risk of developing lung cancer, even in non-smokers. These particles often carry carcinogenic chemicals that can alter DNA, trigger chronic inflammation, and encourage abnormal cell growth over time.

Most Polluted Areas in the U.S.

Air pollution remains a significant public health concern across the United States, with certain regions consistently ranking among the most polluted. According to the American Lung Association’s 2025 “State of the Air” report, nearly 40% of Americans – approximately 131.2 million people – live in areas with unhealthy levels of ozone or particle pollution.

In 2025, the top 10 most polluted cities by ozone are as follows:

1. Los Angeles–Long Beach, CA 2. Visalia, CA 3. Bakersfield–Delano, CA 4. Phoenix-Mesa, AZ 5. Fresno-Madera-Hanford, CA 6. Denver–Aurora–Greeley, CO 7. Houston–Pasadena, TX 8. Sacramento-Roseville, CA 9. Salt Lake City–Provo–Orem, UT-ID 10. Dallas–Fort Worth, TX-OK

How to Protect Yourself from Air Pollution

While large-scale solutions require policy change and long-term planning, there are several ways you can reduce your personal exposure to air pollution in your day-to-day life. These precautions are especially important for people with respiratory issues, heart conditions, children, and older adults – groups more vulnerable to the health risks of air pollution. 

Check the air quality index (AQI daily)

Before heading outside, especially for physical activity, check your local AQI using your weather app or websites like airnow.gov and PurpleAir. On days when pollution levels are high – often marked “unhealthy for sensitive people” or worse – consider rescheduling outdoor plans or reducing exertion. 

Avoid high-traffic and industrial areas

One of the biggest impacts of traffic-related air pollution other than health includes degraded environments and property damage, but its direct health impact is just as concerning. 

Use air purifiers indoors

Indoor air can also be polluted by outdoor sources or household chemicals. HEPA-filter air purifiers can help reduce particulate matter, allergens, and volatile organic compounds (VOCs) indoors.

Keep windows closed when air quality is poor

When pollution levels rise – whether due to traffic, industrial activity, or wildfire smoke – close your windows and doors to keep dirty air outside. Use fans or air conditioning with clean filters to stay comfortable while maintaining indoor air quality.

Wear a proper mask when needed

During wildfires or high-smog days, wearing an N95 or similar mask can filter out fine particles (like PM2.5) that pose serious health threats. Cloth masks are not effective for pollution, so use certified respirators when protection is necessary.

How Can LifeMD Help?

If you're experiencing breathing issues or have concerns about how air quality may be impacting your lungs, a team of licensed providers may be able to help. We offer personalized guidance and, when appropriate, prescription treatment options to support your respiratory health.

Connect with a medical provider today – your lungs will thank you.

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