Air pollution is a mixture of harmful particles, liquids and gases. Outdoor air can be polluted by chemicals and particles released by traffic, industries, farming, energy production and waste burning. Indoor air pollution originates from second-hand smoke, heating and cooking, and everyday products containing harmful chemicals.
Air pollution is associated with at least 28,000 deaths a year in the UK and contributes to breathing issues, heart problems and allergies.
Strong scientific evidence shows that outdoor air pollution, as well as some substances in it, can promote cancer in humans. In addition, some pollutants in outdoor and indoor air may also be Endocrine Disrupting Chemicals (EDCs) that can interfere with our hormones.
Traffic pollution is the main factor contributing to air pollution in the UK. When fuel is burned to power cars, buses and other vehicles, many pollutants are released into the air. Emissions from diesel engines are particularly harmful and diesel exhaust fumes can increase cancer risk.
The main traffic pollutants are particulate matter (PM), polycyclic aromatic hydrocarbons (PAHs) and nitrogen dioxide (NO2), which are all emitted when fuel is burned.
Particulate matter (PM) is a mixture of particles dispersed in air which are small enough to be inhaled. These solid particles can trap and carry other chemicals emitted by traffic, some of which may be cancer-causing or EDCs.
Nitrogen dioxide (NO2) is a gas associated with traffic emissions, particularly diesel engines. Nitrogen dioxide is often measured to estimate the levels of traffic-related pollution. Higher levels of nitrogen dioxide mean poorer air quality.
Most studies have found that traffic-related air pollution may increase breast cancer risk. In particular, high levels of nitrogen dioxide (NO2) are linked to an increased risk of breast cancer.
Exposure to polycyclic aromatic hydrocarbons (PAHs) may also increase risk, whilst the link between particulate matter (PM) and breast cancer is inconclusive. Some evidence, including a recent UK study, has shown that exposure to particulate matter may increase breast cancer risk, whilst other studies found no link.
Whilst traffic is the main source of pollution in urban areas, industrial and farming activities are the main polluters in rural settings. For example, particulate matter (PM) and nitrogen dioxide (NO2) may be released into the air when industrial or farming equipment is used. Some manufacturing and waste facilities may also release harmful chemicals that are unintentionally formed during various processes or whilst waste is burned.
Indoor air pollution is a mixture of chemicals and particles that may be released into our homes by different sources. EDCs and harmful particles may be released by everyday products and from certain appliances. Poor air quality is also linked to outdoor air, lack of ventilation, as well as second-hand tobacco smoke.
Within our homes, products containing fragrances, such as sprays, candles, air fresheners, cleaning and beauty products, may release phthalates and other EDCs into the air. Other chemicals can accumulate in dust, which can be carried in the air and breathed in.
Air pollutants may also be released by some cooking or heating appliances that work by burning gas or wood. Ensuring adequate ventilation in our homes can reduce air pollution and improve air quality.
There is limited evidence on indoor air pollution and breast cancer, but a small number of studies in humans have suggested that burning gas or wood for cooking and heating may increase risk.
Download our “A guide to EDCs: how to reduce your breast cancer risk” to learn more about reducing your exposure to harmful chemicals.
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