How air pollution from cars affects humans

Air pollution from cars harms human health by inflaming the lungs and cardiovascular system, triggering asthma attacks and heart events, increasing risks of cancer and adverse pregnancy outcomes, and contributing to cognitive decline. Exposure occurs outdoors near traffic and inside vehicles during commutes, with children, older adults, pregnant people, and those with existing illnesses most affected. This article explains the pollutants cars emit, how they affect the body, who is most vulnerable, how exposure happens, and what policies and personal actions can reduce harm.

What cars emit and why it matters

Modern vehicles emit a mix of primary pollutants directly from tailpipes and non-exhaust particles from brakes and tires; some emissions also react in sunlight to form new pollutants like ground-level ozone. Even as engines get cleaner, non-exhaust sources and the sheer volume of traffic keep health risks high, especially along busy roads and in dense urban corridors.

The major pollutants linked to traffic

The following list outlines the key harmful pollutants associated with road traffic and how each affects health and the environment.

• Fine and ultrafine particles (PM2.5, PM10, and nanoparticles): penetrate deep into lungs, enter the bloodstream, drive inflammation and oxidative stress; significant shares come from exhaust, brake wear, tire wear, and resuspended road dust.
• Nitrogen oxides (NOx, especially NO2): irritate airways, worsen asthma, and contribute to the formation of ozone and secondary particles.
• Ozone (O3, formed downwind): damages lung tissue, reduces lung function, and exacerbates respiratory diseases—especially on sunny, warm days.
• Carbon monoxide (CO): reduces blood’s oxygen-carrying capacity; dangerous in enclosed or poorly ventilated spaces and for people with heart disease.
• Volatile organic compounds (VOCs) and air toxics (e.g., benzene, formaldehyde, PAHs): some are carcinogenic and can damage the liver, kidneys, and nervous system.
• Black carbon (soot): a component of PM linked to cardiopulmonary harm and climate warming.
• Carbon dioxide (CO2): the primary greenhouse gas from engines, indirectly harming health by intensifying heatwaves, wildfire smoke, and ozone formation.

Together, these pollutants make traffic a dominant source of nitrogen dioxide and a major contributor to particulate pollution in many cities worldwide, with impacts that extend miles downwind from busy corridors.

How car pollution affects the human body

Decades of epidemiological and clinical research show that traffic-related air pollution increases both short-term and long-term health risks. There is no known safe level of fine particulate matter; risk rises as exposure increases, even at levels below many legal standards.

Health effects with the strongest evidence

Below are the health outcomes most consistently linked to traffic-related air pollution in large studies and reviews by agencies such as the World Health Organization (WHO), the U.S. Environmental Protection Agency (EPA), and the International Agency for Research on Cancer (IARC).

• Respiratory: more asthma attacks and new-onset asthma in children, COPD exacerbations, bronchitis, reduced lung growth in children, and increased respiratory infections.
• Cardiovascular: higher risks of heart attacks, strokes, arrhythmias, heart failure exacerbations, and accelerated atherosclerosis.
• Cancer: diesel exhaust and outdoor air pollution are classified as Group 1 (carcinogenic to humans); strongest evidence is for lung cancer, with benzene linked to leukemia.
• Pregnancy and infants: increased risks of preterm birth, low birth weight, and small-for-gestational-age infants; mounting evidence of impacts on infant lung development.
• Neurological: associations with cognitive decline and dementia in older adults, and developmental impacts in children including attention and learning deficits.
• Metabolic and systemic: increased risks of type 2 diabetes, hypertension, and systemic inflammation.
• Eye and airway irritation: immediate symptoms such as coughing, wheezing, sore throat, and eye irritation, especially near heavy traffic.

While individual risk varies, traffic pollution contributes to a significant population burden: ambient air pollution is linked to millions of premature deaths globally each year, with vehicle emissions a substantial contributor in many urban areas.

What’s happening inside the body

Mechanistically, particles and gases trigger oxidative stress and inflammation in the lungs and blood vessels, impair endothelial function, and can disrupt the autonomic nervous system. Ultrafine particles can cross into the bloodstream and have been found in multiple organs; some may reach the brain via the olfactory nerve. These processes help explain rapid effects (such as triggering a heart attack) and long-term disease progression.

Who is most at risk

Air pollution does not affect everyone equally. The following groups face higher exposure, greater susceptibility, or both.

• Children and adolescents: developing lungs and higher breathing rates increase dose; proximity of schools and playgrounds to busy roads adds risk.
• Older adults: more likely to have heart and lung conditions that pollution can exacerbate.
• People who are pregnant and infants: sensitive developmental windows heighten risks.
• Individuals with asthma, COPD, cardiovascular disease, or diabetes: pollution can trigger acute events.
• Low-income and marginalized communities: disproportionately located near highways, depots, and freight corridors, leading to higher chronic exposure.
• Outdoor workers and commuters: spend extended time near traffic or inside vehicles where concentrations can spike.

Reducing exposure and emissions in these settings can yield outsized health benefits and narrow environmental health disparities.

Where and when exposure happens

Traffic-related exposure is highly localized and varies over time. Concentrations are typically highest within a few hundred meters of major roads, during rush hours, and under weather conditions that trap pollutants near the ground.

Near-road and in-vehicle exposure

People can encounter higher concentrations while walking or cycling along busy streets and while driving or riding in vehicles. Cabin air can be two to several times more polluted than general urban air during congestion, tunnels, or close-following of diesel vehicles. Recirculating cabin air and effective filtration can markedly reduce this exposure.

Indoor infiltration and time of day

Traffic pollutants infiltrate homes, schools, and offices, especially in buildings close to major roads or with leaky envelopes. Ozone typically peaks in the afternoon on sunny days downwind of urban centers, while NO2 and primary particles peak with morning and evening traffic.

Trends, technology, and policy

Cleaner engines, catalytic converters, diesel particulate filters, and selective catalytic reduction have decreased tailpipe emissions per vehicle in many countries. However, growth in vehicle miles traveled, non-exhaust emissions (brakes, tires, road dust), and urban congestion keep health risks relevant. Electrification eliminates tailpipe emissions and, via regenerative braking, can reduce brake dust, but tire wear particles and road dust remain challenges.

Recent standards and actions

Regulators are tightening limits on vehicle emissions and promoting zero-emission technologies. In the United States, the EPA finalized multi-pollutant standards for light- and medium-duty vehicles for model years 2027–2032 to cut smog-forming and greenhouse-gas emissions and encourage electric vehicles, and set updated greenhouse-gas standards for heavy-duty trucks through 2032. Similar policies are advancing in the European Union and parts of Asia, while many cities are piloting low-emission or zero-emission zones and expanding clean public transit.

How to reduce harm now

While policy-level changes bring the largest benefits, individuals, schools, and workplaces can meaningfully reduce exposure with practical steps. The following actions focus on exposure reduction and emission avoidance.

• Plan routes: choose side streets or greenways away from heavy traffic for walking, cycling, and jogging; avoid busy roads during rush hours when possible.
• Optimize commuting: use recirculate mode in traffic, keep windows closed in congested corridors, and maintain a high-efficiency cabin air filter; avoid tailgating diesel vehicles.
• Improve indoor air: use well-sealed windows and doors near highways; run HVAC systems with MERV-13 or better filters; use portable HEPA purifiers in rooms facing busy roads.
• Check air quality: follow your local AQI, especially for ozone and PM2.5; reschedule strenuous outdoor activity when levels are high.
• Cut emissions at the source: avoid idling, keep tires properly inflated, maintain vehicles, and consider cleaner options such as public transit, carpooling, walking, cycling, or electric vehicles.
• Protect vulnerable groups: place playgrounds and classroom air intakes away from roadways; use indoor activity alternatives for children on high-pollution days.

Combined, these measures can substantially lower your personal exposure while broader policies continue to reduce emissions at scale.

Key context and numbers

Globally, outdoor air pollution is associated with millions of premature deaths annually, and traffic is a major contributor in urban environments. The WHO’s air quality guidelines advise very low annual targets—such as 5 µg/m³ for PM2.5 and 10 µg/m³ for NO2—because health risks persist even below many national standards. In cities, traffic often dominates NO2 and contributes significantly to PM2.5, making near-road interventions especially impactful.

Bottom line

Car pollution affects humans by damaging lungs and hearts, worsening chronic diseases, increasing cancer risk, and harming pregnancies and brain health. Exposure is highest near busy roads and in vehicles, and it disproportionately affects children, older adults, and communities living by traffic corridors. Policies that cut tailpipe and non-exhaust emissions, expand clean transport, and protect near-road populations, together with practical personal measures, can significantly reduce health risks.

Summary

Air pollution from cars—both exhaust and non-exhaust—drives respiratory, cardiovascular, cancer, pregnancy, and neurological harms through inflammation and oxidative stress. The greatest risks occur near heavy traffic and during commutes, with vulnerable populations bearing disproportionate burdens. Progress in emissions standards and vehicle electrification is reducing tailpipe pollution, but non-exhaust particles and high traffic volumes sustain health risks. Choosing cleaner transport options, optimizing commutes and indoor air, and supporting strong clean-air policies are the most effective ways to protect health now and in the future.

What role do cars play in causing air pollution?

Burning gasoline and diesel fuel creates harmful byproducts like nitrogen dioxide, carbon monoxide, hydrocarbons, benzene, and formaldehyde. In addition, vehicles emit carbon dioxide, the most common human-caused greenhouse gas.

Are car fumes bad for your health?

Car exhaust fumes cause a range of short-term and long-term health effects, including eye, nose, and throat irritation, headaches, dizziness, and nausea. Long-term exposure can lead to serious conditions such as respiratory illnesses like asthma and bronchitis, cardiovascular diseases, and an increased risk of cancer. Certain components, like carbon monoxide (a poisonous gas) and benzene (a carcinogen), are particularly dangerous, with diesel exhaust specifically classified as a carcinogen.
 
Short-Term Effects

• Irritation: Exposure can irritate the eyes, nose, and throat. 
• Neurological Symptoms: Headaches, dizziness, confusion, and nausea can occur. 
• Respiratory Symptoms: Coughing, breathlessness, and wheezing are common, especially with diesel exhaust. 

Long-Term Effects

• Respiratory Damage: Chronic exposure can lead to or worsen respiratory conditions, including asthma, bronchitis, and other chronic lung diseases. 
• Cardiovascular Disease: Fine particulate matter in exhaust is linked to heart attacks, strokes, and other cardiovascular problems. 
• Cancer: Long-term exposure to certain components, such as diesel exhaust and benzene, is linked to an increased risk of lung, bladder, and blood cancers. 
• Neurological Damage: Some chemicals in exhaust can lead to neurological problems, including developmental delays and cognitive impairment. 
• Immune System Damage: Exposure can also harm the immune system. 

Key Pollutants and Their Effects

• Carbon Monoxide (CO): Opens in new tabA poisonous gas that, even in small amounts, can cause headaches, dizziness, and confusion. High levels can be fatal. 
• Particulate Matter: Opens in new tabTiny particles that can enter deep into the lungs and cause respiratory and cardiovascular issues. 
• Benzene: Opens in new tabA hydrocarbon that is a known carcinogen, severely impacting bone marrow and increasing the risk of leukemia. 
• Nitrogen Oxides: Opens in new tabPotent respiratory irritants that can cause wheezing and chronic lung disease. 
• Diesel Exhaust: Opens in new tabClassified as a Group 1 carcinogen by the IARC, increasing the risk of lung and bladder cancer. 

Risk Factors

• Enclosed Spaces: Inhaling exhaust is especially dangerous in enclosed spaces, such as in a garage with an exhaust leak. 
• Urban Areas: People living in densely populated urban areas face a higher risk of pollution-related health problems. 
• Pre-existing Conditions: Individuals with pre-existing lung or heart conditions are more vulnerable to the effects of exhaust exposure. 

How does air pollution affect us as humans?

Air pollution affects humans by causing short-term problems like coughing, wheezing, and asthma attacks, and long-term issues including heart disease, stroke, lung cancer, chronic obstructive pulmonary disease (COPD), and even premature death. These pollutants, primarily inhaled through the respiratory system, can lead to inflammation, oxidative stress, and damage to various organs such as the heart, brain, and lungs, contributing to a wide range of systemic illnesses.
 
Respiratory & Cardiovascular Effects

• Respiratory Illnesses: Opens in new tabShort-term exposure can trigger coughing, wheezing, shortness of breath, and asthma attacks. Long-term exposure can lead to chronic bronchitis, COPD, and an increased risk of lung cancer. 
• Cardiovascular Problems: Opens in new tabPollutants can increase blood pressure and heart rate, making blood more likely to clot. This increases the risk of heart attacks, strokes, and high blood pressure. 

Neurological & Systemic Effects

• Brain Health: Opens in new tabResearch indicates that air pollution is linked to negative impacts on neurological health, potentially contributing to dementia. 
• Immune System: Opens in new tabAir pollution can suppress the immune system, making individuals more susceptible to infections. 
• Other Systemic Issues: Opens in new tabLong-term exposure to air pollution has also been associated with diabetes mellitus, reproductive disorders, and obesity. 

Mechanism of Harm

• Inflammation & Oxidative Stress: Opens in new tabWhen you breathe polluted air, pollutants enter your respiratory tract and trigger inflammation and oxidative stress in cells throughout the body. 
• Systemic Impact: Opens in new tabThis inflammation and oxidative stress can spread to other organs, including the heart and brain, and contribute to the development of various chronic diseases. 

Vulnerable Populations

• Children and Elderly: Opens in new tabChildren and the elderly are particularly vulnerable to the health effects of air pollution. 
• People with Pre-existing Conditions: Opens in new tabThose with existing heart or respiratory conditions are at a higher risk of severe health impacts from air pollution. 

How much of air pollution is caused by vehicles?

According to the Environmental Protection Agency, as much as 95 percent of all CO emissions in cities may come from motor vehicle exhaust. Nitrogen dioxide (NO2) — when fuel burns, nitrogen and oxygen react with each other and form nitrogen oxides (NOx).