What you may have heard
You might’ve heard that living near highways or breathing in car exhaust can increase cancer risk. Some people compare it to secondhand smoke in terms of long-term health effects.
What science tells us
Traffic-related air pollution contains known carcinogens including benzene, diesel exhaust, and fine particulate matter (PM2.5). Repeated exposure, especially in high-density urban or highway-adjacent areas, has been linked to increased risk of lung cancer in both occupational and residential settings. Children and older adults are especially vulnerable.
Epidemiological Evidence
- A Danish study of over 54,000 adults found that higher exposure to nitrogen oxides at home was also linked to higher risks of brain cancer and cervical cancer, with incidence rate ratios (IRRs) over 2. These findings suggest that traffic-related air pollution may contribute to cancer beyond the lungs. (PMID: 21771295).
- A 2015 meta-analysis of 36 studies found that traffic-related air pollution is significantly associated with lung cancer. Key pollutants linked to higher lung cancer risk included fine particulate matter (OR 1.11), nitrogen oxides, and sulfur dioxide. Professional drivers, who face high occupational exposure, had a 27% higher incidence of lung cancer (PMID: 26273377).
Laboratory Evidence / Supporting Evidence
Diesel exhaust and ultrafine particles from vehicles can lead to cancer. Animal studies confirm tumor development with long-term exposure to traffic-related air pollutants.
IARC Carcinogen Classification
- Diesel engine exhaust: Group 1 – Carcinogenic to humans
- Gasoline engine exhaust: Group 2B – Possibly carcinogenic
- Benzene, PM2.5, 1,3-butadiene, and formaldehyde: Group 1 – Carcinogenic
How to reduce your risk
- If you live close enough to a highway to hear traffic, using an indoor air purifier with a HEPA and activated carbon filter can help lower particle and gas pollutants that drift indoors.
- When driving in heavy traffic, keeping the windows closed and setting the car’s ventilation to “recirculate” reduces how much pollution comes in from outside.
- Electric vehicles can help reduce tailpipe pollution in cities, which lowers exposure for nearby residents over time, but they do not eliminate all traffic-related pollution because tire and brake wear still produce particles.
Bottom line
Traffic emissions contain multiple confirmed human carcinogens. Living or working near heavy traffic increases cancer risk, especially for lung cancer. Reducing long-term exposure helps lower your risk.