What is Particulate Matter?
Particulate matter pollution is made up of very small liquid and solid particles floating in the air. The greatest concern to health are particles small enough to be inhaled into the deepest parts of the lung. These particles are about 1/7th the thickness of the a human hair. There are two kinds of particulate matter; coarse particulate matter(PM10) and fine particulate matter (PM2.5).
The larger particles or PM10 usually contain earth crust materials and fugitive dust from roads and industries. Fine particles usually contain acidity that is found in larger particulate matter and in fog acid droplets are also present. Sources of particulate matter can be both man made or natural. Increased levels of fine particles in the air are linked to serious health hazards such as heart disease, altered lung function and lung cancer.
Particulate matter can include dust, dirt, soot, smoke and liquid droplets that can be suspended in the air for long periods of time. Some particles are large or dark enough to be seen as soot or smoke. Others are so small that individually they can only be detected with an electron microscope.
Another component of particulate matter is black carbon (BC). Often called soot, black carbon is one of the most important absorbing aerosol species in the atmosphere. BC from fossil fuels is discussed by the Inter-Governmental Panel on Climate Change (IPCC) in the Fourth Assessment Report of the IPCC. For further information see the report at http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-spm.pdf.
Where Does Particulate Matter Come From?
There are both natural and human sources of atmospheric particulates. The biggest natural sources are dust, volcanoes, and forest fires. Sea spray is also a large source of particles though most of these fall back to the ocean close to where they were emitted. The biggest human sources of particles are combustion sources, mainly the burning of fuels in internal combustion engines in automobiles and power plants, and wind blown dust from construction sites and other land areas where the water or vegetation has been removed. Some of these particles are emitted directly to the atmosphere (primary emissions) and some are emitted as gases and form particles in the atmosphere (secondary emissions).
Particulates may also come from a variety of sources such as unpaved roads, stone crushing, burning of wood, and construction sites. Particles can be formed in the air from the chemical change of gases and when gases from burning fuels (gaseous precursors such as sulfur dioxide, nitrogen oxides or organic compounds) react with sunlight and water vapor.
Fine particles are generally composed of sulfate, nitrate, metals, chloride and ammonium compounds, organic and elemental carbon. Combustion of coal, oil, diesel, gasoline, and wood, as well as high temperature process produce emissions that contribute to fine particle formation.
Fine particles can remain in the atmosphere for days to weeks and travel through the atmosphere hundreds to thousands of miles. Most coarse particles typically return back to the earth minutes to hours and within a few miles from the emission source. The particles that travel can include wind-blown dust from uncovered soil, unpaved roads or mining operations. Traffic produces road dust and air turbulence that can stir up road dust.
Near coasts, evaporation of sea spray can produce coarse or large particles. Pollen grains, mold spores, plant and insect parts are all in this larger size range. Combustion of fossil fuels such as coal, oil and gasoline can produce coarse particles from the release of non-combustible materials, (i.e. fly ash, fine particles from the condensation of materials vaporized during combustion, and secondary particles through the atmospheric reactions of sulfur oxides and nitrogen oxides initially released as gases).
How can Particulate Matter effect my family and my community?
The effects of inhaling particulate matter have been widely studied in humans and animals. Effects include asthma, lung cancer, cardiovascular issues and premature death.The size of the particle is a main determinant of where in the respiratory tract the particle will come to rest when inhaled. Larger particles are generally filtered in the nose and throat and do not cause problems, but coarse or PM10 particulate matter can settle in the bronchi and lungs and cause health problems.
Similarly, fine particles or PM2.5 particles tend to penetrate into the gas-exchange regions of the lung, and may pass through the lungs to affect other organs. A study published in the Journal of the American Medical Association http://jama.ama-assn.org/cgi/content/full/295/10/1127 indicated that PM2.5 leads to high plaque deposits in arteries, causing vascular inflammation and atherosclerosis — a hardening of the arteries that reduces elasticity, which can lead to heart attacks and other cardiovascular problems. It has been suggested that even short-term exposure at elevated concentrations could significantly contribute to heart disease.
Even smaller particles can be even more damaging to the cardiovascular system. There is evidence that these tiny particles can pass through cell membranes and migrate into other organs, including the brain. It has been suggested that particulate matter can cause similar brain damage as that found in Alzheimer patients. Particles emitted from modern diesel engines (commonly referred to as Diesel Particulate Matter, or DPM) are typically in this size range.
What Can I Do to Decrease Particulate Matter in My Community?
A variety of ways for a community to reduce emissions, include:A few things individuals and organizations can do immediately to reduce the threat of PM10: