学术文献库

The influence of human activity own the earth's atmospheric composition has never been more pronounced. Anthropogenic pollution is in fact the largest effector of the observed evolving atmospheric composition (Wallace, 2006). PM2.5 is a class of particulate matter pollutants of notable interest due to their significant driving of chemical, atmospheric change, their wide-scale, global circulations, and their malignant effects on human health; with a diameter of less than 2.5 microns; PM2.5s derive from combustion of organic materials, including fossil fuel combustion (Wallace, 2006) and forest fires (Newman, 2007). The gases released in these combustion reactions then condense in the atmosphere, undergoing gas to particle conversion, resulting in the atmospheric presence of PM2.5s. Particulate matter (PM) pollutants are harmful to human health in all diameter scales; increasing in recent years global morbidity and mortality (Araujo, 2011). The health risks of PM2.5 in particular are troubling due to their small size, which facilities their permeability in the respiratory system and ready diffusion into the bloodstream, inducing pathologies like ischaemic heart disease, respiratory infections, and lung cancers to name a few (Araujo, 2011). Once PM2.5 manifest in the atmosphere, they circulate on a larger scale due to atmospheric circulation patterns. Though government-enacted air quality measures have reduced the average PM2.5 levels in North America, pollution episodes still cause localized, acute PM2.5 exposure. The purpose of this project was to analyze PM2.5 mean concentration across America to identify and quantify any pollution episodes, as well as try to explain their dynamics using large scale, meteorological processes.