Health Risks (Particle Pollution)

Health Risks | Ozone | Particle Pollution | Children's Health | At-Risk Populations

Ozone and particle pollution are the most widespread air pollutants—and among the most dangerous. Recent research has revealed new insights into how they can harm the body—including taking the lives of infants and altering the lungs of children. All in all, the evidence shows that the risks are greater than we once thought.

Two types of air pollution dominate the problem in the U.S.: ozone and particle pollution.

Particle Pollution
Ever look at dirty truck exhaust? The dirty, smoky part of that stream of exhaust is made of particle pollution. More new evidence shows that the particle pollution—like that coming from the exhaust smoke—can lead to shorter lives, heart disease, lung cancer and asthma attacks and can interfere with the growth and work of the lungs.

What Is Particle Pollution?
Particle pollution refers to a mix of very tiny solid and liquid particles that are in the air we breathe. But nothing about particle pollution is simple. First of all, the particles themselves are different sizes. Some are one-tenth the diameter of a strand of hair. Many are even tinier; some are so small they can only be seen with an electron microscope. Because of their size, you can’t see the individual particles. You can only see the haze that forms when millions of particles blur the spread of sunlight. You may not be able to tell when you’re breathing particle pollution. Yet it is so dangerous it can shorten your life.

The differences in size make a big difference in how they affect us. Our natural defenses help us to cough or sneeze larger particles out of our bodies. But those defenses don’t keep out smaller particles, those that are smaller than 10 microns (or micrometers) in diameter, or about one-seventh the diameter of a single human hair. These particles get trapped in the lungs, while the smallest are so minutethat they can pass through the lungs into the blood stream, just like the essential oxygen molecules we need to survive.

Researchers categorize particles according to size, grouping them as coarse, fine and ultrafine. Coarse particles fall between 2.5 microns and 10 microns in diameter and are called PM10-2.5. Fine particles are 2.5 microns in diameter or smaller and are called PM2.5. Ultrafine particles are smaller than 0.1 micron in diameter11 and are small enough to pass through the lung tissue into the blood stream, circulating like the oxygen molecules themselves. No matter what the size, particles can be harmful to your health.

Because particles are formed in so many different ways, they also can be composed of many different compounds. Although we often think of particles as solids, not all are. Some are completely liquid; some are solids suspended in liquids. As the U.S. Environmental Protection Agency puts it, particles are really “a mixture of mixtures.”12 The mixtures differ between the eastern and western United States. For example, the eastern states have more sulfate particles than the west, largely due to the high levels of sulfur dioxide emitted by large, coal-fired power plants. By contrast, in Southern California, nitrate particles from motor vehicle exhaust form a larger proportion of the unhealthful mix.13

Where Does Particle Pollution Come From?
Particle pollution is produced through two separate processes—mechanical and chemical. Mechanical processes break down bigger bits into smaller bits with the material remaining essentially the same, only becoming smaller. Mechanical processes primarily create coarse particles.14 Dust storms, construction and demolition, mining operations, agriculture, and coal and oil combustion are among the activities that produce coarse particles.

By contrast, chemical processes in the atmosphere create most of the tiniest fine and ultrafine particles. Combustion sources burn fuels and emit gases. These gases can vaporize and then condense to become a particle of the same chemical compound. Or, they can react with other gases or particles in the atmosphere to form a particle of a different chemical compound. Particles formed by this latter process come from the reaction of elemental carbon (soot), heavy metals, sulfur dioxide (SO2), nitrogen oxides (NOx) and volatile organic compounds with water and other compounds in the atmosphere.15 Burning fossil fuels in factories, power plants, steel mills, smelters, diesel- and gasoline-powered motor vehicles (cars and trucks) and equipment generate a large part of the raw materials for fine particles. So does burning wood in residential fireplaces and wood stoves or burning agricultural fields or forests.

What Can Particles Do to Your Health?
Studies showing the dangers of particle pollution are pouring in by the thousands. The new studies validate earlier research showing a strong relationship between particle pollution and illness, hospitalization and premature death.16

Researchers these days are exploring possible differences in health effects of the three sizes of particles and particles from different sources, such as diesel particlesfrom trucks and buses or sulfates from coal-fired power plants. So far, the evidence remains clear that all particles from all sources are dangerous.17

Particle pollution can damage the body in ways similar to cigarette smoking. A recent review of the research on how particles cause harm found that the body responds to particles in similar ways to its response to cigarette smoke. These findings help explain why particle pollution can cause heart attacks and strokes.18

Short-term Exposure Can Be Deadly
First and foremost, short-term exposure to particle pollution can kill. Deaths can occur on the very day that particle levels are high, or within one to two months afterward. Particle pollution does not just make people die a few days earlier than they might otherwise—these are deaths that would not have occurred if the air were cleaner.19 Particle pollution also diminishes lung function, causes greater use of asthma medications and increased rates of school absenteeism, emergency room visits and hospital admissions. Other adverse effects can be coughing, wheezing, cardiac arrhythmias and heart attacks. According to the findings from some of the latest studies, short-term increases in particle pollution have been linked to:

  • death from respiratory and cardiovascular causes, including strokes20,21,22,23
  • increased mortality in infants and young children24
  • increased numbers of heart attacks, especially among the elderly and in people with heart conditions25
  • inflammation of lung tissue in young, healthy adults26
  • increased hospitalization for cardiovascular disease, including strokes and con
    gestive heart failure27,28,29
  • increased emergency room visits for patients suffering from acute respiratory ailments30
  • increased hospitalization for asthma among children31,32,33
  • increased severity of asthma attacks in children34

Year-Round Exposure
Breathing high levels of particle pollution day in and day out also can be deadly, as landmark studies in the 1990s showed conclusively.35 Chronic exposure to particle pollution can shorten life by one to three years.36 Other impacts range from premature births to serious respiratory disorders, even when the particle levels are very low.

Year-round exposure to particle pollution has also been linked to:

  • increased hospitalization for asthma attacks for children living near roads with heavy truck or trailer traffic37,38
  • slowed lung function growth in children and teenagers39,40
  • significant damage to the small airways of the lungs41
  • increased risk of dying from lung cancer42
  • increased risk of death from cardiovascular disease43

Alarmingly, the risks may be even greater than previously thought. Earlier studies of the long-term health risks of air pollution relied on estimates of the average exposure to people in the community. New evidence from studies published since 2005 suggests that those estimates may be far too low. Tracking 23,000 residents of Los Angeles and looking at data from monitors nearest to them, researchers found that the risk of premature death from fine particle pollution may be three times higher than previously reported.44 New research into risks to the health of 65,000 women over age 50 found that those who lived in areas with higher levels of particle pollution faced a much greater risk of dying from heart disease than had been previously estimated. Even women who lived within the same city faced differing risks depending on the annual levels of pollution in their neighborhood.45

Who Is at Risk?
Anyone living in an area with a high level of particle pollution is at risk (you can take a look at levels in your state in this report). People at the greatest risk from particle pollution exposure include those with lung disease such as asthma and chronic obstructive pulmonary disease (COPD), which includes chronic bronchitis and emphysema; people with sensitive airways, where exposure to particle pollution can cause wheezing, coughing and respiratory irritation; the elderly; people with heart disease; and children. New research points to ever-larger groups at higher risk, including diabetics, and most recently, women over 50.46