Particulate Pollution Linked to Cancer, Premature Births

All around the world, air pollution is wreaking havoc on health. Experts at the World Health Organizations do not have data from every country, but in the countries that do collect air pollution data, four out of five residents of cities face levels of pollution greater than recommended as safe. More than 98 percent of residents of cities with populations over 100,000 in low or middle income countries suffer serious health risk.

Experts place the blame for deteriorating health in cities all over the planet on particulate matter. Particulate matter pollution or dust pollution of the air is a well-known contributor to heart disease and cancer that most of us never give a second thought. How you choose the place you live, whether it's in a dusty area or not, can have a huge impact on your long-term health.

What Is Particulate Matter Pollution?

Just about everybody is familiar with particulate matter in the air. When you can see dust in the air, that's particulate matter. When you can feel the spray from an ocean wave, that's also particulate matter. Pollen is also particulate matter. In the "Smoky" Mountains, trees emit so much pollen in the spring that they appear to be covered with smoke. For that matter, smoke itself is also particulate matter.

The difference between particulate matter and particulate matter pollution is the size of the particles in the air. Some visible particulate matter is so bulky that it gets stuck in the cilia, tiny hairs, of our noses. Even if we inhale it, it is too bulky to reach the innermost passages in the lungs. Tiny particles, however, can penetrate not just deep into the lungs but into the bloodstream itself, carrying other forms of chemical pollution along with them.

What Are Some Examples of Particulate Matter Air Pollution?

"Fine" particulate matter is defined as particles with a diameter of 2.5 microns (millionths of a meter) or less. Inhalable particulate matter has a diameter of 2.5 to 10 microns. Particles larger than 10 microns don't get into the lungs, for the most part. Here are some common examples.

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• The dust you might see settling in the streets after a dust storm or haboob after a summer thunderstorm in the desert has particle sizes of 10 to 100 microns. Particles of this size can cover your cart in grime, but they don't get into your lungs.
• The dust that settles on your furniture has particle sizes of 1 to 10 microns. You may breathe in some of it, but you probably won't inhale all of it.
• The dust you see floating in the air around the house when you haven't used your vacuum cleaner in a while has particle sizes of 0.01 to 1 microns. All of this can go into your lungs.
• Some pollen, most bacteria, most cat dander, most mold spores, and all viruses are small enough to be inhaled.
• Cement dust, oil smoke, auto engine particulates, fly ash, coal ash, soot, and compounds released from wood fires and kerosene are all small enough to be inhaled.

What Goes Wrong When You Inhale Particulate Matter Pollution, and What Can You Do About It?

It probably won't come to a surprise to anyone that particulate matter is related to lung cancer. Tiny particles can pick up carcinogenic chemicals and carry them deep into the lungs. These tiny particles, whether not someone smokes cigarettes, can cause changes in DNA that lead to cancer, and may explain why most people who smoke don't get cancer and some people who don't smoke nonetheless get the disease. However, it isn't just lung cancer that can becomes more common with exposure to particulate matter.

Between 1998 and 2011, researchers in Hong Kong enrolled residents over the age of 65 to study the relationship between exposure to fine particle pollution (from buses, cars, boats, power plants, and industrial activity) and cancer. The research team used 13 years of satellite data to calculate cumulative exposure to particulate matter. In older people, cancer tends to emerge as the result of cumulative exposure to carcinogens; the more carcinogens that have gone into your body, the more likely you are to get cancer. The researchers confirmed that the cancer-causing effects of small particle air pollution on cancer are cumulative. For every 10 micrograms per cubic meter average particulate matter pollution to which Hong Kong residents were exposed, there was a:

• 22 percent greater risk of developing some kind of cancer,
• 40 percent greater risk of developing esophageal cancer, and, in women,
• 80 percent greater risk of developing breast cancer.

In fact, it wasn't just cancer that was more common with more exposure to particulate pollution. Researchers on this team also found that exposure to soot, smoke, engine exhaust, and other fine particulate matter increased risk of:

• Heart disease. Exposure to fine particles, particles the size of germs, activates the immune system. The white blood cells that attack germs also feed on cholesterol, so increased immune system activity can result in greater atherosclerosis.
• Peptic ulcer disease. Exposure to particulate matter pollution increases the risk of stomach ulcers although not intestinal ulcers. People who lived in parts of Hong Kong where pollution was greater had up to a 53 percent greater risk of having to be hospitalized for gastric ulcers.
• Influenza and pneumonia. On days when there was the most particulate matter in the air, the greatest numbers of people over 65 had to be hospitalized for pneumonia or flu.
• Hospital admissions for any reason. All illnesses are made worse by high levels of air pollution, but the effects are greater for higher-income families than for lower-income families. The researchers found that spikes in air pollution had less of an effect on health outcomes for families living on less than $250 a month, which is to say, in poverty. Of course, this could be because they are sick all the time. However, the highest-income families in Hong Kong suffered the greatest increases in illnesses when particulate matter levels spiked.

Particulate air pollution can even effect the unborn. All over the world, except in the United States, data find a relationship between cumulative exposure to particulate air pollution and low birth weight. Exposure to this form of air pollution during part of the pregnancy is bad, but exposure during the entire pregnancy is worse. In the United States, ozone is a greater factor in low birth weight babies than particulate pollution; however, American cities have made considerable progress in controlling this form of pollution.

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If you are like four out of five of the world's city dwellers and you live in a region where this form of bad air can hurt your health, what can you do?

• It's especially important to take precautions during pregnancy in China, India, the Middle East, and North Africa. Prevailing winds carry soot and smoke from China and India westward almost to the eastern coast of North America. Anywhere in this zone, it is healthier to get a pregnant woman out of any city. Low birth weight babies are up to 250 percent more common in the most polluted parts of China.
• The more you avoid wood fires, commercial kitchens (especially those that cook meat over wood), kerosene lamps, and exposure to diesel exhaust, the better it will be for your overall health, no matter where you live in the world.
• It's never too late to make a difference. Exposure to particles in the air is cumulative. If you stop the exposure, your condition at least doesn't get worse. Breathe the cleanest air you can and choose the cleanest locations you can for optimal health.