Air pollution is one of the world’s largest killers, responsible for 6.4 million deaths per year (1 in 9 deaths), of which 600,000 are children. This is more than the number of deaths from AIDS, Malaria and tuberculosis combined. The World Health Organization estimates that 2 billion children live in areas where outdoor air pollution exceeds international limits and 300 million children live in areas where outdoor air pollution exceeds 6 times international limits. Children, the elderly, and people with heart or lung disease, diabetes, minority and low - income communities are particularly vulnerable to adverse health outcomes from exposure to air pollution, including cardiovascular disease, asthma and other respiratory diseases, and cancer. Recent evidence suggests that air pollution is also linked to higher risk of diabetes, autism, and lower IQ.
What we typically think of as "air pollution" is actually a mixture of small particles (such as: black carbon gases like nitrogen oxides, ozone, and sulfur dioxide.
Particulate matter (PM10, PM2.5)
Particulate matter (PM) is made up of small airborne particles like dust, soot, and drops of liquids. The majority of PM in urban areas is formed directly from burning of fossil fuels by power plants, automobiles, non-road equipment, and industrial facilities. Other sources are dust and diesel emissions and secondary particle formation from gases and vapors.
Coarse particulate matter (PM10, particles < 10 microns in diameter) is known to cause nasal and upper respiratory tract health problems. Fine particles (PM2.5, particles < 2.5 microns in diameter; Ultra Fine Particles) penetrate deeper into the lungs and cause heart attacks, strokes, asthma, and bronchitis, as well as premature death from heart ailments, lung disease, and cancer. Studies show that higher PM2.5 exposure can impair brain development in children.
Black Carbon (BC)
Black carbon is one of the components of particulate matter and comes from burning fuel (especially diesel, wood, coal, and others). Most air pollution regulations focus on PM2.5, but exposure to black carbon is a serious health threat as well. Populations with higher exposures to black carbon over a long period are at a higher risk for heart attacks and stroke. In addition, black carbon is associated with hypertension, asthma, chronic obstructive pulmonary disease (COPD), bronchitis, and a variety of types of cancer.
Nitrogen Oxides (NO and NO2)
Nitrogen oxide (NO) and Nitrogen dioxide (NO2) are produced primarily by the transportation sector. NO is rapidly converted to NO2 in sunlight. NOx (a combination of NO and NO2) is formed in high concentrations around roadways, and can result in development and exacerbations of asthma, bronchitis, as well as lead to a higher risk of heart disease.
Ozone high up in the atmosphere can protect us from ultraviolet radiation. But ozone at ground level (where it is part of what is commonly called smog) is a well-established respiratory irritant. Ozone is formed in the atmosphere through reactions of volatile organic compounds and nitrogen oxides, both of which are formed as a result of combustion of fossil fuels. Short-term exposure to ozone can cause chest pain, coughing, throat irritation, while long term exposure can lead to decreased lung function and cause chronic obstructive pulmonary disease (COPD). In addition, ozone exposure can aggravate existing lung diseases.
Sulfur dioxide (SO2)
SO2 is emitted into the air by the burning of fossil fuels that contain sulfur. Coal, metal extraction and smelting, ship engines, and heavy equipment diesel equipment burn fuels that contain sulfur. Sulfur dioxide causes eye irritation, worsens asthma, increases susceptibility to respiratory infections, and impacts the cardiovascular system. When SO2combines with water, it forms sulfuric acid; this is the main component of acid rain, a known contributor to deforestation.