Air quality warning system improving, but long way to go; old data a problem: Study, Pg4.

Key Highlights:

• Delhi's Air Quality Early Warning System (AQEWS) accurately predicted high-pollution days over 80% of the time [in the winters of 2023-24 and 2024-25].
• The AQEWS, run by IITM Pune and IMD, forecasts Delhi's air quality three days in advance.
• A study by CEEW found the system's effectiveness is limited by outdated emission inventories and underprediction of pollutant levels.
• The Commission for Air Quality Management (CAQM) announced in December 2024 it would no longer use the Decision Support System (DSS) due to outdated inventories.

Detailed Insights:

• The AQEWS struggles to detect the most severe air pollution episodes, although prediction of episodes with AQI > 400 improved from 1 out of 15 in 2023-24 to 5 out of 14 in 2024-25.
• The study highlighted the persistent underprediction of particulate matter pollution, with Mean Absolute Percentage Error (MAPE) for PM2.5 forecasts at 35% and PM10 at 37% in 2023-24.
• The DSS currently operates only in winter, limiting its ability to track pollution sources year-round, and should incorporate modeling scenarios for better air quality improvements.
• The Graded Response Action Plan (GRAP) implementation is reactive, with restrictions imposed after AQI thresholds are breached, rather than preemptively based on forecasts.
• The study recommends updating India’s emission inventories every two to three years, making forecast data publicly available, and running the DSS year-round for stronger air quality mitigation.

Key Concepts Involved:

• Air Quality Index (AQI): A metric used to communicate the level of air pollution and associated health risks.
• Emission Inventory (EI): A comprehensive list of pollutants released from various sources within a specific area and time frame.
• Graded Response Action Plan (GRAP): A set of measures implemented in stages to combat air pollution based on air quality levels.