Particulates or particulate matter (abbreviated as PM), are suspended solid and liquid particles in our atmosphere. They are considered significant polluters of our air and have health implications. Particulates are divided according to their size and the two main classes are PM2.5 and PM10, i.e. particulate matter smaller than 2.5 microns (micrometers) and particles larger than 2.5 microns and smaller than 10 microns in size. These are typically generated by combustion of fossil fuels, including coal and petroleum products (petrol or gasoline, diesel, etc.). They are hazardous to our health since they can enter our blood stream and lungs and lead to cardiovascular diseases. One advantage of particulate matter is that they reflect solar radiation, thus reducing the amount of solar energy reaching earth's surface, thereby limiting the effects of global warming.
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