Particulate Matter

Particulate Matter

News: The Centre has set a new target of 40 percent reduction in particulate matter concentration in cities covered under the National Clean Air Programme (NCAP) by 2026, updating the earlier goal of 20 to 30 percent reduction by 2024.

What is Particulate Matter (PM)?
• Particulate matter, or PM, is the term for particles found in the air, including dust, dirt, soot, smoke, and liquid droplets. Particles 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.
• Many manmade and natural sources emit PM directly or emit other pollutants that react in the atmosphere to form PM.

PM distinguished based on size:
• These particles come in a wide range of sizes.
• Particles less than 10 micrometers in diameter (PM10) pose a health concern because they can be inhaled into and accumulate in the respiratory system.
• Particles less than 2.5 micrometers in diameter (PM2.5) are referred to as “fine” particles and are believed to pose the greatest health risks.
• Particles with diameters between 2.5 and 10 micrometers are referred to as “coarse”.
• Because of their small size (approximately 1/30th the average width of a human hair), fine particles can lodge deeply into the lungs.

What are the sources of PM?
• Sources of fine particles include all types of combustion activities (motor vehicles, power plants, wood burning, etc.), forest fires and certain industrial processes.
• The secondary source of pollution can be due to complex reactions of chemicals like sulphur dioxide and nitrogen oxide. These particles are mixed in air and pollute it.
• Apart from these, forest fires, wood burning stoves, agricultural burning, smoke of the industry, dust occur from various construction sites also causes air pollution.
• Some indoor sources of fine particles are tobacco smoke, cooking (e.g., frying, sautéing, and broiling), burning candles or oil lamps, and operating fireplaces and fuel-burning space heaters (e.g., kerosene heaters).

What is the impact of exposure to PM on the human health?
• For PM2.5, short-term exposures (up to 24-hours duration) have been associated with premature mortality, increased hospital admissions for heart or lung causes, acute and chronic bronchitis, asthma attacks, emergency room visits, respiratory symptoms, and restricted activity days.
• Adverse health impacts have been primarily seen in infants, children and older adults (with pre-existing heart and lung issues)
• Long-term (months to years) exposure to PM2.5 has been linked to premature death, particularly in people who have chronic heart or lung diseases, and reduced lung function growth in children.
• According to a study, increase in PM2.5 by one microgram per cubic metre reduces life expectancy by three weeks, which implies that such alarming increases could chop off a significant portion of one’s healthy years.

What steps can be used to lower PM 2.5 levels in atmosphere?
• Particulate/Wet Scrubbers - In a wet scrubber, the polluted gas stream is brought into contact with the scrubbing liquid, by spraying it with the liquid, by forcing it through a pool of liquid, or by some other contact method, so as to remove the pollutants.
• Electrostatic Precipitators - Electrostatic precipitators are highly efficient filtration devices that minimally impede the flow of gases through the device, and can easily remove fine particulates such as dust and smoke from the air stream.
• Focus on NOx control – Opting for low NOx burners, using NOx scrubbers.

About NCAP:
• It is the first-ever effort in the country to frame a national framework for air quality management with a time-bound reduction target.
• The goal of NCAP is to meet the prescribed annual average ambient air quality standards at all locations in the country in a stipulated timeframe.
• Under NCAP, 131 cities are being targeted for improving air quality.
• Of these 131 cities, 123 cities (NACs) are identified under NCAP based on non-conforming to national ambient air quality standards (NAAQS) consecutively for five years. In addition, million plus cities (MPCs) are also covered, those identified by 15 th Finance Commission (XV-FC), for receiving performance based grant for air quality improvement.
• According to the Union Environment Ministry, 95 of the 131 non-attainment cities covered under the NCAP have witnessed an “overall improvement” in PM10 levels in 2021 as compared to 2017 levels.
• In Delhi, the PM10 concentration has reduced from 241 micrograms per cubic metre in 2017 to 196 micrograms per cubic metre in 2021.