Particulate matter (PM) consists of a wide range of materials in solid or liquid phase that range in size from less than 1 nanometer up to one hundred micrometers and can have complex chemical composition.
Some of the components include nitrates, sulfates, metals, organic compounds, soil, pollen, soot, etc. Particulate matter (PM) is measured using a variety of size metrics, of which the most common are PM10 and PM2.5. Both are measures of the mass of particles with an aerodynamic diameter of less than 10 or 2.5 micrometers, respectively.
There are a large number of sources of particulate matter, with stationary combustion (e.g., non-mobile sources, such as power plants) being one of the major contributors, along with road transportation. Among the stationary, fuel combustion sources are industrial sector activities like iron and steel manufacturing, the residential sector heating and power stations.
Emissions of PM from the combustion of solid fuels (like coal) are, in general, larger in diameter than those originating from the combustion of liquid fuels, and the latter are coarser than particles generated from gas combustion. But in general, particles produced by combustion are smaller in diameter than 1 micrometer.
Some environmental impacts of particulate matter emissions are reduction in visibility, acid rain, and damage and stain on materials (statues and monuments).
Deposition of particulate matter can also contribute to the acidification of lakes and rivers, change the nutrient balance of water bodies and soil, and affect forests and farm crops .
Particulate matter can cause severe health problems in humans, especially the particles whose diameter is smaller than 10 micrometers, since they can be inhaled deeply into the lungs and even be absorbed into the bloodstream.
The most common health effects of particulate matter are respiratory symptoms such irritation of the air passages, coughing, difficulty in breathing, decreased lung function, asthma, chronic bronchitis and premature death .