What is PM 2.5?Particulate matter (PM) or particle pollution in the air is a mixture of airborne tiny particles and liquid droplets that is consists of tiny solid fragments, liquid fragments and fragments mixing with both solid and liquid. These tiny fragments are made up of various components, such as acids, toxic exhaust, organic chemicals, metal, dust, soot, soil, or a mixture of these components.
There are many classes of particulates. However, among these classes, PM 10 and PM 2.5 are the mostly regulated ones.
- PM 10 refer to inhalable coarse particles that are with diameter of about 10 micrometers.
- PM 2.5 refer to fine particles that are with diameter 2.5 micrometers and smaller.
The above diagram showing size distribution of different types of airborne particles in micrometres (µm).
Sources of PM 2.5There are both natural and anthropogenic (i.e. manmade) sources of PM 2.5. Carbonaceous (organic) material from traffic causes a direct adverse effect on health and has been identified as a most evident source of PM2.5. Burning fuels such as oil, gasoline, or wood can directly contribute to the rising of PM levels. On the other hand, windblown dust and chemical reactions between different gases (e.g., nitrogen, sulfur, phosphorus etc.) and other substances (e.g., ammonia) can indirectly enhance the rising of atmospheric PM levels.
Power stations as well as Industrial sources contribute most to manmade pollutions (35%), trailed by vehicles or road traffic (24%), suburban (13%), and shipping (10%). Natural sources of particulate matter include sea salt that results 5-15% of urban background PM 2.5 and with higher contributions found near the coastal areas.
Health effects of PM 2.5Exposure to airborne particulate matter (PM) has harmful consequences on human health, the environment, and climate change. Many researches have already provided much information concerning the hazardous adverse effects of PM exposure.
As PM 2.5 are finer particles, they can penetrate deeply and travel through the respiratory system to reach the lung. The Committee on the Medical Effects of Air Pollutants (COMEAP) reported that high-level exposure to PM could increase hospital admissions and premature death of the old and sick because of respiratory and cardiovascular system illnesses. As evidence, the COMEAP showed a statistical data on high pollution days and this data revealed that both PM 10 and PM 2.5 caused additional hospital admissions and premature deaths.
Long-term PM exposure is associated with chronic respiratory, cardiovascular, and neurological diseases, including lung cancer, neurodevelopment disorders, poor cognitive function, diabetes, and heart attack.
Short-term PM exposure during pollution episodes can produce less severe effects, including temporary breathing difficulty, worsening of asthma symptoms, feeling of unwell, decreased activity level, etc.
In addition to adverse health effects, PM 2.5 also have other widespread effects on environment and climate change. The environmental effect can contribute to biodiversity loss, damaging plants as well as corrosion of buildings.
- Air Quality Expert Group (2012). Fine Particulate Matter (PM2.5) in the United Kingdom. http://uk-air.defra.gov.uk/reports/cat11/1212141150_AQEG_Fine_Particulate_Matter_in_the_UK.pdf
- COMEAP (2009). Long-Term Exposure to Air Pollution: Effect on Mortality. The Committee on the Medical Effects of Air Pollutants.
- COMEAP (2010). The Mortality Effects of Long-Term Exposure to Particulate Air Pollution in the United Kingdom. The Committee on the Medical Effects of Air Pollutants.
- Regulatory Actions and Particulate Matter - US EPA - http://www.epa.gov/pm/actions.html