PM2.5 Air Pollution Threshold and Toxicity Levels
Recent research has brought into light the critical threshold for PM2.5 air pollutants in Kolkata. The study reveals that once PM2.5 concentration surpasses 70 micrograms per cubic metre (µg/m³), its potential to cause cellular damage increases . This finding is crucial as it indicates a need for new air quality standards that consider toxicity levels, not just concentration.
About PM2.5 and Its Impact
PM2.5 refers to particulate matter with a diameter of less than 2.5 micrometres. These tiny particles can penetrate deep into the lungs and enter the bloodstream. They originate from various sources, including vehicular emissions, industrial processes, and biomass burning. Due to their size, they pose a serious health risk, leading to respiratory and cardiovascular issues.
Toxicity Thresholds in Kolkata
The study, conducted by researchers at the Bose Institute, found that the toxicity of PM2.5 sharply rises after crossing the 70 µg/m³ threshold. Between 70 and 130 µg/m³, the potential for harm increases. Beyond this point, toxicity stabilises, indicating a saturation point for cellular damage.
Mechanism of Damage
At lower PM2.5 concentrations, the human body can manage the adverse effects of inhalation. However, exceeding the threshold overwhelms the body’s defence mechanisms. The immune system releases Reactive Oxygen Species (ROS) to combat pollutants. Unfortunately, high levels of ROS can lead to oxidative stress, damaging cells.
Role of Antioxidants
Antioxidants are crucial for neutralising ROS. However, their production is limited and slow. When PM2.5 levels are high, the body cannot produce enough antioxidants to counteract the excess ROS, leading to increased cellular damage and health risks.
Variability of Threshold Levels
The toxicity thresholds for PM2.5 may vary by city. Different urban areas have distinct pollutant compositions. For instance, cities with higher biomass burning may experience different toxicity levels compared to those dominated by vehicular emissions.
Policy Implications for Air Quality Standards
Current air quality standards focus primarily on concentration levels. In India, a yearly average of 40 µg/m³ for PM2.5 is deemed safe. However, this does not account for toxicity. The research suggests that a concentration of 70 µg/m³ should trigger alerts, as the health risks increase at this level.
Need for Toxicity-Based Standards
The study advocates for the establishment of toxicity-based air quality standards. Such standards would enable timely warnings and emergency actions when pollution levels exceed the identified thresholds, ultimately protecting public health more effectively.
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