September 22nd, 2013 by Michael Ricciardi
Each year millions of premature deaths world-wide result from various forms of air pollution. According to a new atmospheric pollution model designed by earth scientist Jason West of the University of North Carolina (data from which informs the NASA map shown above), some 2.1 million deaths per year result from just one particular form of atmospheric pollution: fine particulate matter, or PM2.5, which is emitted in car exhaust and smokestack effluent (and other industrial, domestic and natural sources).
In general, these polluting particles in the atmosphere are referred to as aerosols (a mixture of particulate matter and air). Aerosols can take the form of suspended particulate matter (SPM), respirable suspended particles (RSP), which are particles with a diameter of 10 micrometers (microns) or less, and, the aforementioned fine PM2.5…the ‘2.5’ refers to particles of 2.5 microns or less and may include ultrafine particles, and some forms of soot (such as black carbon soot from cooking stoves and biomass burning).
Sometimes transient, natural, meteorological conditions combine with human pollution, resulting in “extreme outbreaks of air pollution.” For example, in January, 2013, a blanket of industrial pollution enveloped northeastern China, and, in June, 2013, smoke from agricultural fires in Sumatra engulfed Singapore.
Health researchers have linked PM2.5 with everything from asthma to lung disease, and even heart attacks (perhaps caused from the stress of not getting sufficient oxygen into the lungs). But the longer-term impacts of this form of pollution can be far more insidious. According to NASA’s Earth Observatory website:
‘In most cases, the most toxic pollution lingers for a few days or even weeks, bringing increases in respiratory and cardiac health problems at hospitals. Eventually the weather breaks, the air clears, and memories of foul air begin to fade. But that’s not to say that the health risks disappear as well. Even slightly elevated levels of air pollution can have a significant effect on human health. Over long periods and on a global scale, such impacts can add up.’
The map shows regions around the globe with significant numbers of annual deaths due to particulate pollution. The darker the coloration the greater the death rates, with the darkest coloration indicating death rates as high as 1,000 deaths per 1,000 square kilometers.
One can easily identify vast regions in Central/Eastern Europe, Southern and Northern India, South/Southeast Asia, and most of Japan as having the darkest coloration. These areas typically include highly populated, extensively urbanized areas.
Areas colored blue (Southern US, mid South America) represent more positive trends where reductions in smog and other particulate pollution (mostly from agricultural burning) have been dramatically reduced since the 1850’s. Sadly, there are very few such regions, globally speaking, perhaps due to the lack of air quality laws.
This newest model by West et al combines 6 different atmospheric models into one — a major improvement over their 2010 estimate that relied on just one model (which included premature mortality estimates from ozone and PM 2.5 pollution). The pollution models used to inform this map include historical data going back 160 years — to the beginnings of the Industrial Revolution.
The details of their premature mortality estimation (for the 2.1 million deaths cited) can be found in their March, 2013 paper ‘Global premature mortality due to anthropogenic outdoor air pollution and the contribution of past climate change‘ published in Environmental Research Letters.
Map Credit/Source: Map made by NASA’s Robert Simmon based on data from Jason West
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