It is hard to avoid air pollution. We are exposed to different levels of air pollution wherever we go. We are exposed to it when we travel to and from work or school, and when we play or exercise outdoors. We are exposed to certain kinds of air pollution in our homes and offices, and during the normal course of our daily activities. How much air pollution we are exposed to depends on how many chemicals or particles are in the air, how fast we breathe, and how much time we spend indoors or outdoors. This website is designed to help you learn more about air pollution, and to provide you with information that will help you reduce your exposure to harmful pollution levels.
The sources of air pollution vary from area to area and from day to day. Cars, trucks, buses, and other "mobile sources" are often major contributors to air pollution in California, but industrial plants and consumer products, such as paints or cleaning products that are used in many homes, can also cause air pollution. Fires and dusty operations can also contribute to air pollution.
It is unlikely that we will be able to completely avoid polluting the air, but we are making good progress in reducing unwanted and harmful air pollutants. Learning about air pollution and how to reduce your exposure is a good first step in protecting your health. Local air districts, the California Air Resources Board, and the U.S. Environmental Protection Agency are good sources of information on air quality and its health effects. The information provided below was drawn from all three of these governmental agencies. Additional references are given for those who want to learn more.top
What is ozone? Ozone is a gas that occurs in the Earth's upper atmosphere (protective ozone) and at ground level (harmful ozone). Ground level ozone results from the interaction of nitrogen oxides with volatile organic compounds in the presence of sunlight. The primary sources of these gasses are cars and trucks, and in California we get lots of sunlight from spring through fall which is our typical "ozone season."
Ozone is a very reactive chemical. It is an oxidant that can react on contact with the cells lining the surface of the lungs to form other reactive chemicals such as hydrogen peroxide. Ozone and its reactive products are strong irritants to the lungs and can trigger an asthma episode and worsen bronchitis.
Who is most at risk from ozone exposure? Health risks from ozone are primarily a function of the duration and level of exposure, whether we are exercising or working outdoors, and our health status. Children and adults who are active outdoors have greater exposures because they breathe faster, thereby inhaling more ozone and breathing it deeper into their lungs. People with respiratory diseases such as asthma, emphysema, and bronchitis may experience increased symptoms and difficulty breathing when ozone levels are high. Some healthy people are more sensitive to ozone, and experience health effects at lower levels of ozone during moderate levels of outdoor activity than the average person.
What are common symptoms of ozone exposure? Many people experience one or more of the following: irritation of the nose and throat, increased mucus production and tendency to cough, eye irritation, and rapid shallow breathing. When ozone reaches very high levels, most people experience discomfort when breathing and difficulty taking a deep breath without coughing. People with asthma may experience asthma attacks. Sometimes symptoms of asthma may not occur until hours after exposure to ozone. For some people who live in areas where ozone levels are frequently high, there may be no symptoms or they may be too subtle to notice.
Short-Term effects of ozone. Exposures to high levels of ozone air pollution (e.g., air quality index significantly greater than 100) during exercise can result in respiratory symptoms of irritation, decrease in lung function, and airway inflammation in some people. High ozone levels may increase emergency room visits, hospitalizations, and possibly mortality. How susceptible any person is to the effects of ozone depends on their age, genetic differences, activity levels and duration, and pre-existing health conditions (e.g., asthma, bronchitis, and emphysema). Some individuals adapt to high ozone levels and are less responsive than people in low ozone environments. Some people may experience few symptoms and little change in lung function during exposure, but develop inflammation in their airways hours after exposure.
The body's response to high ozone levels may not always be felt right away, making it important for people who are at risk to be aware of the air quality index (AQI) for ozone so they can reduce their exposure when necessary and/or medically manage their asthma.
Long-Term effects of ozone. Unlike short-term exposures, chronic or long-term exposure to ozone may cause irreversible changes in lung function that may become a concern for respiratory health later in life. In one scientific study, Yale College students who had lived for four years or more in areas with high summer ozone levels (AQIs above 100) showed decreased lung function. Similar effects were seen in first year students at the University of California at Berkeley. Scientists are also looking into a possible causal relationship between asthma and ozone exposures. In the Children's Health Study conducted in southern California, children who competed in three or more sports over several years were compared to children who played no sports in communities with seasonally high ozone. The more active children were more likely to experience symptoms of asthma and develop new cases of asthma.
How to reduce exposures to ozone. People can learn when to reduce their exposure to ozone by paying attention to air quality reports and forecasts that notify the public when ozone levels are at unhealthy levels. In the U.S., state and local government agencies use EPA's AQI to report air quality to the public. You can sign-up for air quality notices for the Imperial Valley by clicking on the tab "Air Quality Notifications."
You can reduce exposures to ozone by 20 to 80 percent by remaining indoors. While outdoors, you can reduce ozone exposures by reducing the intensity of your activities. Work or play that makes you breathe significantly harder also increases the amount of ozone inhaled deeper into your lungs.
Where can I find more information on the health effects of ozone?
What is particulate matter? Particulate matter (PM) is a complex mixture of solid and liquid particles suspended in air that vary in size and composition. Sources of PM include dust from the earth's surface, biologic material such as pollen and spores, combustion sources such as forest fires, heating furnaces, power plants, factories and internal combustion engines (cars, trucks, buses, ships, trains, and construction equipment). The size, composition, and concentration of PM depend on its sources.
Particle size determines how likely different particles are to deposit in different parts of the respiratory tract. The smaller the particles, the deeper they can travel into the lungs. The composition and concentration of chemicals found in PM contribute to its toxicity. Particles can contain: metals like iron, nickel, and copper; ions such as sulfate and nitrate; organic compounds; biological materials such as viruses and bacteria, and reactive gases such as ozone and peroxides.
The particles of concern for health effects are those that are readily inhaled into the lungs, typically 10 micrometers (µm) or less in diameter. For comparison, a human hair is about 60 µm in diameter and a human red blood cell is about 7 µm in diameter. Airborne particles ranging in size between 10 and 1 µm are generated from dust from unpaved roads and wind-blown dust. Smaller particles (around 2.5 µm and less) are generated from diesel and gasoline engines, tire and brake wear, and some agricultural practices. Particles less than 1 µm are combustion related or are formed by condensation of much smaller particles (less than 0.1 µm) and constitute smoke and haze.
U.S. EPA regulates PM in two size categories, 10 µm or less (PM10) and 2.5 µm or less (PM2.5, "fine"). U.S. EPA is currently in the process of revising the national standards for these two categories of PM. Fine and ultrafine (less than 0.1 µm) particles are of most concern because they can be inhaled very deep into the lungs. These small particles can be more toxic because they have much larger surface areas on a weight-for-weight basis than larger particles (e.g., compare a pound of rocks with a pound of sand). Large surface areas allow easy transfer of soluble chemicals into cells lining the lungs. Very small particles may even penetrate into the bloodstream.
How do particles affect my lungs? Coughing is your body's first line of defense, as it naturally tries to clear the airways of any deposited particles. Particles that remain in the airways can induce an inflammatory response. This inflammation can cause damage to the cells lining the lungs and other cells in the airways. Such damage may reduce the body's defense mechanisms and increase susceptibility to infections if exposed to viruses and bacteria. The inflammatory response can cause certain constituents of the blood to clot. Particles can also affect the nervous system, changing our pattern of breathing, heart rate, and heart rate variability. These changes are more likely to affect persons who already have heart or lung disease.
Health effects from short-term exposures to PM. Healthy children and adults may experience temporary symptoms that include: coughing, phlegm, chest tightness; shortness of breath, and irritation of the eyes, nose and throat. Shortâ€‘term exposures over a few hours or a day can exacerbate lung disease, causing asthma attacks and acute bronchitis. Particulate air pollution can also increase susceptibility to respiratory infections such as colds, the flu, or bronchitis. In people with heart disease, such as coronary artery disease and congestive heart failure (heart can't pump enough blood to the body's other organs), short-term exposures have been linked to ischemia (reduced blood flow and oxygen delivery to the heart), heart attacks, and cardiac arrhythmias (irregular heart rhythms). Episodes of high levels of particulate air pollution have also been associated with increased hospital and emergency room visits. Epidemiological studies have shown an increase in mortality from heart and lung disease within a few days following high levels of PM.
Health effects from long-term exposures to PM. The effects of exposure to high PM levels over many years can be similar to short-term exposure. School-aged children may experience decreased lung function from long-term exposures to PM in combination with other air pollutants (nitrogen dioxide and acid vapors). These changes in lung function are not reversible and add to the normal decline in lung function that occurs later in life.
Who is most at risk from PM exposures? Older adults (60+ yrs) with heart and lung disease are likely to experience more severe effects from short-term exposures to PM compared to healthy adults. Epidemiological studies have shown an increase in mortality from heart or lung disease within a few days following high levels of PM. Premature mortality appears to be associated with both PM10 and PM2.5.
People with asthma may experience more intense or more frequent symptoms or attacks. People with diabetes may be at greater risk to the health effects of particulate air pollution. Infants and very young children may be more at risk to long-term PM exposures because their lungs are still in a rapid stage of development, and because children breathe more air per lung volume and body weight than adults. Healthy school-aged children are at lower risk to short-term PM exposures. Although scientists have just started researching these effects, there is some evidence for neonatal or infant mortality, low birth weight, and higher rates of premature deliveries associated with PM exposure.
How to reduce exposures to PM. Exposures to PM can occur both indoors and outdoors. To reduce your exposure to outdoor air pollution, try to limit your activities to times when air quality is better. Try to play and exercise at least 500 feet away from busy freeways and roads. When you drive in your car, especially in stop-and-go traffic, it is important to try to keep your windows closed and the air conditioner running (if you have one). Outdoor particles can seep in through doors, windows, and even ventilation systems. Properly equipped and functioning air ventilation and filtration systems can reduce indoor levels of PM. Not smoking indoors will markedly reduce indoor PM.
Where can I find more information on health effects of PM?
What is carbon monoxide? Carbon monoxide is an odorless and colorless gas formed from the incomplete combustion of organic (carbon-containing) matter. The largest source of carbon monoxide is from vehicular exhaust, up to 95% in cities. Other sources include wildfires, some industrial processes, and kerosene and gas-fired appliances that are not properly vented. The highest exposure to carbon monoxide comes from smoking cigarettes.
How does carbon monoxide affect my health? Exposure to low levels of carbon monoxide can cause headaches, nausea, or heart pain. Those most susceptible include infants, small children, the elderly and heart and respiratory patients. Carbon monoxide competes with oxygen to bind to the hemoglobin proteins in your blood. Because it binds more tightly to hemoglobin than oxygen, it tends to build up in the blood even when exposure levels are low. Carbon monoxide can also remain elevated hours after exposures have decreased.
The feeling of carbon monoxide poisoning is similar to the feeling of being at high altitude where there is less oxygen in the air. The brain and the heart must have an adequate supply of oxygen to function; decreased oxygen to the brain and central nervous system results in slowed reaction times, light-headedness, and headaches. Exposure to very high levels of carbon monoxide can cause oxygen starvation of the brain, leading to coma and even death. Such a condition is not likely in outdoor air, but could occur indoors when appliances are not properly vented or if a lawn mower or vehicle is operated inside a closed garage.
Who is most at risk from carbon monoxide exposures? People with certain types of heart disease are most at risk. For example, people with angina may experience chest pain and other cardiovascular symptoms while exercising. People with ischemic heart disease (reduced blood flow and oxygen delivery to the heart) are susceptible to carbon monoxide. The narrowing of their coronary arteries (often from plaque) physically restricts blood flow to their heart tissue that cannot compensate for low oxygenated blood due to carbon monoxide exposures. Low oxygen conditions disturb normal heart rhythms and can lead to a heart attack. Pregnant women should avoid exposure to high levels of carbon monoxide because of potential harm to their babies.
How to reduce exposures to carbon monoxide. Because carbon monoxide is colorless and odorless there is no warning that you are being exposed. Carbon monoxide levels are highest during the winter because cars don't operate as efficiently in colder temperatures. Winter weather conditions often produce inversions that trap colder air beneath a layer of warmer air that results in less mixing of air pollutants and higher ground levels of carbon monoxide. Vigorous outdoor activities on such days should be reduced if carbon monoxide levels are in the "unhealthy" category. Carbon monoxide poisoning can be prevented by proper use, maintenance, and venting of any appliances that produce a flame. Care should also be taken not to operate car engines or other gas-powered equipment in enclosed or attached garages.
Where can I find more information on carbon monoxide?top
Epidemiology studies of the health effects of air pollution look at large populations exposed to the pollution in the air where they live. In these studies, it can be difficult to determine which of the observed health effects are due to a single air pollutant or a combination of pollutants. Individual air pollutants are best evaluated in controlled breathing chamber studies; however, these are limited to a smaller number of people. Toxicology studies examine the effects of single chemicals and mixtures of pollutants on laboratory animals and specific cell types. By comparing the results from epidemiology, breathing chamber, and toxicology studies we can determine how air pollution affects the body, and how we can better protect our health.
Information from epidemiology and toxicology studies indicates that both ozone and PM can affect the respiratory system, and that people with asthma are sensitive to both pollutants. The combination of PM and carbon monoxide can affect people with heart disease. Chronic exposure, over multiple years, to PM2.5, nitrogen dioxide, acidic vapors, and elemental carbon may be associated with changes in lung development in children 10 to 18 years old. Whether each of these four pollutants contributed to changes in lung function is uncertain since these pollutants are typically found together in urban air.
Ozone and PM together can intensify the inflammatory response in people with asthma. Exposure to ozone and PM together may also cause a reduction in heart rate variability, the natural ability of the heart to change rhythm in response to exercise and stress.
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