New Delhi (ABC Live) :Air Pollution Impact : Air pollution comes in many forms, contaminating the air we breathe both indoors and outdoors. Some of the most pernicious constituents of air pollution are tiny particles measuring less than 2.5 microns in diameter, capable of penetrating deep into the lungs.
Collectively referred to as PM2.5, these particles may contain a mix of dust, dirt, smoke, vapors, gases, microscopic liquid droplets, and even heavy metals. Depending on their composition, they may come from a variety of sources.
Direct sources of ambient PM2.5 commonly include emissions from motor vehicles and power plants. Indoor sources of PM2.5 include smoke from burning solid fuels such as coal, wood, charcoal, or dung for cooking and heating.
Secondary PM2.5 may occur when primary pollutants such as ammonia from agricultural fertilizers react with sunlight, water, oxygen, and other pollutants. Though the composition and sources of air pollution can vary greatly from place to place, pollution is truly a global challenge.
The results of the GBD 2015 show that exposure to air pollution—including ambient PM2.5, household PM2.5 from cooking with solid fuels, and ambient ozone—caused nearly 6.5 million premature deaths in 2015, accounting for more than one in ten deaths worldwide .
The number of fatalities from illnesses caused by pollution exposure is about 5.4 times the number of deaths each year from HIV/AIDS and 8.8 times that from malaria (IHME 2016), making air pollution the fourth-leading fatal health risk, just after tobacco smoke.
These estimates of the disease burden attributable to air pollution in the GBD 2015 are derived by first measuring the severity of air pollution and the extent to which people are exposed (Brauer et al. 2016; Cohen et al., forthcoming; Forouzanfar et al. 2016). Estimates of exposure to ambient PM2.5 combine information from satellite observations of aerosols, numerical models of atmospheric chemistry, and ground monitoring of PM (van Donkelaar et al. 2016; Shaddick et al. 2017).
Exposure to household PM2.5 is estimated using data on the proportion of people reliant on solid fuels, the resulting concentrations of PM2.5 in the kitchen from cooking with those fuels, and the level of personal exposure of men, women, and children in the household to those kitchen concentrations.
The GBD 2015 then evaluates how exposure raises people’s relative risk of contracting illnesses associated with air pollution, including lower respiratory infections, lung cancer, ischemic heart disease, stroke, chronic obstructive cardiopulmonary disease, and pneumonia (see Burnett et al. 2014).
Cause-specific models of relative risk combine information from epidemiological studies of the effects of exposure to widely varying levels of PM2.5 from ambient air pollution, household air pollution, active cigarette smoking, and second-hand smoke.
These models then allow researchers to estimate what portion of recorded deaths from these illnesses can be statistically attributed to pollution exposure. Estimates of exposure to ambient PM2.5 for the GBD 2015 reveal that 92 percent of the world’s population in 2015 lived in areas with average annual concentrations in excess of World Health Organization guidelines (map 9.1).
Air quality is deteriorating in many fast-growing, fast-urbanizing regions, particularly South Asia and East Asia and Pacific, whereas air quality has improved on the whole in other regions such as Europe and North America.
Trends in exposure to household air pollution, by comparison, show signs of mixed progress. The share of the world’s population reliant on solid fuels dropped from about 52 percent in 1990 to 40 percent in 2015.
Rates of solid fuel use dropped the fastest in middle-income countries such as China. Yet, because the When the health impacts of air pollution are broken down by age, it becomes clear that pollution is particularly damaging to the elderly.
Individuals age 65 years and older make up about 8 percent of the world’s population but account for 61 percent of fatalities due from illnesses attributed to air pollution. In Sub-Saharan Africa, in particular, a high portion of fatal health effects due to air pollution also are suffered by children younger than age 5 years. Children represented 16 percent of the region’s population in 2015 and 26 percent of pollution-attributed deaths.
Source : The Changing Wealth of Nations 2018