Long-term exposure to fine particulate air pollution is associated with an 11 percent higher risk of developing cancer and a 12 percent higher risk of cancer-related death, according to a major global evidence review.
The report, commissioned by the Union for International Cancer Control, synthesizes findings from 42 systematic reviews and meta-analyses to assess the relationship between air pollution and cancer. It confirms that air pollution is not only a well-established cause of lung cancer but is also linked to a broader range of malignancies.
Across the studies analyzed, both outdoor and indoor air pollution were identified as risk factors for lung cancer. Evidence also suggests associations with cancers of the breast, colorectum, liver, kidney, brain, cervix, and ovary, as well as childhood leukemia.
Fine particulate matter, smaller than 2.5 µm diameter (PM2.5), emerged as the most significant contributor. For every 10 µg/m³ increase in long-term exposure, overall cancer risk rose by 11 percent, with particularly strong links to liver and colorectal cancers. Mortality risk also increased, including higher death rates from breast, liver, and lung cancers. Larger particles (PM10) were also associated with increased cancer risk, though to a slightly lesser extent.
Long-term exposure to polluted air was also linked to increased risk of developing cancer - including a 63 percent higher risk of brain cancer. Because PM2.5 particles are small enough to cross the blood-brain barrier, it is thought that the increased brain cancer risk is a consequence of long-term absorption of pollution.
Indoor air pollution remains an important but less studied factor. Use of solid fuels for cooking and heating was linked to a 69 percent higher risk of lung cancer, with disproportionate exposure among women and children in low-resource settings.
The report highlights substantial inequities, with higher risks observed in populations living near industrial sources of pollution and in low- and middle-income countries. It recommends expanding the body of evidence for links between cancer and air pollution and increasing advocacy for the adoption of national air quality standards.
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