What Are Particulate Matter 2.5 Pollutants?
Particulate matter (PM), also known as particle pollution, is a mixture of airborne tiny particles and liquid droplets. This mixture consists primarily of minute solid fragments, liquid fragments, or a combination of both.
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.
A Closer Look at PM Classes: PM10 and PM2.5
There are many classes of particulates. However, among these classes, PM10 and PM2.5 stand out as the most significant due to regulatory measures associated with them.
- PM 10 refer to inhalable coarse particles that are with diameter of about 10 micrometers. To put this in perspective, a single strand of human hair is about 70 micrometers in diameter, so PM10 particles are significantly smaller and invisible to the naked eye.
- PM 2.5 are fine particles with diameters of 2.5 micrometers and below. They're so tiny that when compared to a human hair, you could fit about 28 PM2.5 particles across its width!
The above diagram showing size distribution of different types of airborne particles in micrometres (µm).
Sources of PM 2.5
There 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 2.5
Exposure 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.
Particle pollution in the air causes shades of grey and pink in sky.
Environmental and Climatic Impact of PM2.5
PM2.5 pollution extends beyond human health, adversely affecting the environment and contributing to climate change. The environmental implications can lead to biodiversity loss, inflict damage on plants, and contribute to the corrosion of buildings and other structures.
On a broader scale, particulate matter in the atmosphere can influence the color of the sky, lending shades of grey and pink. This is due to the scattering and absorption of light by particles in the air, an optical effect known as Rayleigh scattering.
Understanding the consequences of particulate matter pollution is the first step towards mitigating its effects. A collective effort from industries, governments, and individuals can make a significant difference in reducing PM levels, improving both human and environmental health in the process.
Medical References
- 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
