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Information collected by the World Health Organization (WHO) from 4,300 cities in 108 countries indicates that 9 out of 10 people breathe air that contains high levels of pollutants, which are responsible for 7 million deaths annually. The pollutants are a complex mixture of solid and liquid droplets containing sulfates, nitrates, carbon, and other toxins that are inhaled into the lungs with each breath.
Outdoor air pollution contains thousands of components derived primarily from cars, industry, power generation, and home heating using oil, coal, or wood. Such pollutants can lead to health problems including asthma, chronic obstructive pulmonary disease, lung cancer, blood clots, strokes, inflammation, and heart disease, mainly coronary artery disease.
Pollution concentrations often vary during the day, depending on weather conditions such as wind direction and speed, temperature, and sunlight that affect chemical reactions that produce toxins such as ozone. Traffic-related pollutants, like ultrafine particles and soot, often peak during the morning and evening rush hours, causing high exposure for commuters.
Even though people in most Western societies spend about 90% of their time indoors, predominantly in their own homes, outdoor air pollution infiltrates buildings, and most of the exposure typically occurs indoors. The problem is especially prominent when solid fuels are used for cooking and heating, or from cigarette smoking in the home.
More than 80% of the world’s population lives in areas in which particulate matter reaches or is above thresholds recommended by the World Health Organization. The WHO data show that U.S. cities on the polluted list include Los Angeles, Bakersfield, Napa, Calexico and Fresno, California; Indianapolis and Gary, Indiana; Louisville, Kentucky; and St. Louis, Missouri. More than 40% of the world’s population does not have access to clean cooking technology or lighting, making travel to cities like Peshawar and Rawalpindi, Pakistan; Varanasi and Kanpur, India; Cairo, Egypt; and Al Jubail, Saudi Arabia risky from an air pollution perspective. Cleaner air can be found in some cities in Arizona, Wyoming, Colorado, Alaska, and Hawaii.
What Can We Do about Air Pollution?
Fortunately, air pollution is a modifiable condition that can be reduced by replacing driving with walking, biking, or taking public transportation. For outdoor joggers, exposure to high levels of air pollution does not reduce the benefits of physical activity on both the incidence and the recurrence of heart attacks. Individuals at risk, such as those with heart problems or the elderly, can stay inside when air pollution levels are high. Installing filtration equipment in the home ventilation system can also reduce exposure.
Finally, we need to urge our politicians to develop standards for environmental risk factors such as air pollution and pass laws to protect us from these health risks.