Fine-Particle Air Pollution

Women living and working in areas with high levels of fine-particle air pollution — think smoke, dust, and soot — seem to have a higher risk of developing breast cancer than women who live and work in less polluted areas.

Fine-particle air pollution, also called fine particulate matter air pollution or ambient fine particulate matter, is made up of tiny pieces of solid or liquid material in the air. The particles are grouped according to size: coarse, fine, and ultrafine.

Fine particles are between 0.1 microns and 2.5 microns in diameter and are called PM2.5 by scientists. 

One micron is .000393710 inches or .001 millimeters.

These particles can be from things that are burned — like liquid fuels, coal, or wood — or from organic compounds, like the chemicals that give paint its smell. The particles also can be tiny pieces of metal.

It’s difficult for your body to get rid of fine particles. If you breathe them in, they can penetrate deep into lung tissue and move into the bloodstream. From there, scientists believe the particles can be absorbed into breast tissue. While researchers aren’t sure exactly how the particles cause cancer to develop, it may be that the pollutants allow cells in breast tissue with pre-existing mutations to become cancerous, possibly through inflammatory processes, similar to what scientists have seen in non-smokers with lung cancer.

This type of research can’t account for all of the factors that might be responsible for higher breast cancer risk, but does suggest that high levels of fine-particle air pollution may be partially responsible for increased risk.

Exhaust from motor vehicles and particles from mining operations and agriculture, as well as the increasing number of wildfires around the world all contribute to poor air quality and higher levels of fine-particle air pollution in many areas.

Unhealthy air can be very concerning, but air quality indexes can help monitor the air quality in your area and help you stay safe.

For air quality in the United States, visit AirNow.gov, which allows you to put in your ZIP code, city, or state to see the air quality around you.

In Europe, you can find air quality stations using the European Air Quality Index.

IQAir is an international air quality site that allows you to look at air quality on a world map. It also lists the cities with the best and worst air quality.

When the air quality in your area is bad:

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  Limit the time you spend outside to less than 30 minutes, and reduce the intensity of any outdoor activities you’re doing. So instead of running for 25 minutes, walk instead.

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  If you must be outside, consider wearing a well-fitted N95 or KN95 mask. Since the COVID-19 pandemic, these masks are available at many stores and online.

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  Keep your indoor air healthy by keeping your windows and doors closed. If you run an air conditioner, run it on the recirculate setting. You also may want to use an air cleaner or purifier with a HEPA (high-efficiency particulate air) filter.