Previous Year Question

Respirable Suspended Particulate Matter (RSPM) consists of extremely small solid particles and liquid droplets suspended in the air that can enter the lungs during respiration. One micron is equal to one-millionth of a metre (10⁻⁶ metre). The penetration and deposition of fine particles within the respiratory system depend primarily on their Aerodynamic Diameter.

The major sources of Particulate Matter (PM) include vehicle emissions, industrial activities, thermal power plants, coal and biomass combustion, construction activities, and road dust. Some particles are emitted directly into the atmosphere, while others form through chemical reactions involving gases such as Sulfur Dioxide (SO₂) and Nitrogen Oxides (NOₓ). Larger particles generally deposit more frequently in the nose, throat, and upper respiratory tract, whereas smaller particles can penetrate deeper into the respiratory system.

Under modern air-quality classification, PM₁₀ refers to particles with an aerodynamic diameter generally equal to or smaller than 10 micrometres, whereas PM₂.₅ includes particles measuring 2.5 micrometres or less. PM₂.₅ particles are classified as Fine Particles. They can penetrate deep into the lungs, and some may also enter the bloodstream. Therefore, the 5-micron threshold should not be regarded as a universal scientific definition of all respirable particles; different health and environmental standards use different particle-size thresholds.

Fine Particulate Pollution is an important contributor to respiratory and cardiovascular health problems. Prolonged exposure can increase the risks of Asthma, reduced lung function, Chronic Obstructive Pulmonary Disease (COPD), cardiovascular diseases, and lung cancer. Children, older adults, and individuals with existing respiratory or cardiovascular conditions are particularly vulnerable. According to the World Health Organization (WHO), both PM₂.₅ and PM₁₀ are important air pollutants whose concentrations are monitored in air-quality assessments.