Written by Joyce Lee '22
Edited by Ashwin Palaniappan
As the world continues to industrialize, the planet suffers its consequences—and the effects of environmental changes on health grow even more noticeable by the day. Air pollution poses a unique challenge to pollution response because it respects no state borders and cannot be selectively avoided. 9 out of 10 people breathe air with high levels of pollutants, and ambient air pollution is estimated to contribute to approximately 7 million deaths per year. 
One may argue that air pollution, and the seasonal winds that brought pollutants such as smoke or dust from one region to another, has always existed. But the continuous and increasing output of industrial waste, from fossil fuel combustion to desertification due to deforestation into the atmosphere, has resulted in an increased amount of a specific and more harmful pollutant than naturally occurring ones.  These pollutants,“particulate matter” or PM2.5, are particles that are approximately 2.5 microns in diameter. Approximately 24 times smaller than a strand of human hair, PM2.5 poses a unique threat to human health by being so small that it “penetrates” the lungs and cardiovascular system directly, without being filtered at the lungs.
The makeup of PM2.5 is diverse and can range from soot from wildfires to organic chemicals and heavy metals from industrial function. Therefore, studies that analyze the impact of PM2.5 are region-specific, as the makeup of pollutants contribute to the toxicological potency of pollution.  Not only does this make pinpointing the mechanism by which PM2.5 causes disease difficult, but it also makes the conclusions gained from one study difficult to translate exactly to another region.
However, through widespread studies throughout regions some common impacts can be found. For example, it was found that PM2.5 has an adverse effect on child lung function development, as measured through the change in volume of the air children could exhale after they were exposed to residential air pollution in sites around Europe.  PM2.5 is also associated with cancer development not just in the lungs, but in various organs, as seen through a Hong Kong study.  And it is well-established that PM2.5 is associated with cardiovascular disease, with cardiovascular events—any incidents that cause damage to the heart such as heart attacks—“spiking” days after a pollution event, and large increases in cardiovascular mortality (76%!) per 10 micrograms of PM2.5.  Considering that the worst-polluted city in the world, Gurugram, India, is subject to 52.5 micrograms of pollution a day on average, we can only imagine the effects of this amount of pollution on the population. 
But the regional nature of air pollution means that one could go their entire lives without encountering any significantly noticeable amount of bad air, and another could be born into grey-and-yellow skies that they know to be the only reality. Rapid economic growth is associated with the highest levels of air pollution, as many forms of economic development “necessitates extraction of natural resources and accumulation of waste.”  As such, there is a strong correlation between rapidly developing economies and the worst-polluted air—the five countries with highest real GDP growth in 2018 were within the first 22 countries with most polluted capitals, with Bangladesh and India (fourth and third in GDP growth, respectively) claiming the titles of first and third in terms of pollution.  
According to a Greenpeace report published in 2019, awareness of air pollution remains low in areas without data collecting mechanisms. When governments around the world are struggling to deal with the impact of air pollution on their populations, there are, of course, the practical steps: to move away from using pollutants, to sponsor sustainable energy. But another step that must not be overlooked in the search for a long-term solution is to establish mechanisms that can detect air pollution.
Information should not be underestimated – information about pollution levels is necessary for citizens to take protective measures, for political groups to raise awareness, for governments to recognize the severity of the situation, and for all groups party to the conflict, take action against air pollution.
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