Delhi's Air Quality Index Reaches Severe Levels for First Time This Season Amid Dense Fog

Delhi experienced the worst air quality in India on Wednesday, with the Air Quality Index (AQI) reaching the severe category for the first time this season. The central pollution authority attributed this to an unusually dense fog, calling it an episodic event. The city's AQI at 4 pm was 418, up from 334 the previous day, potentially triggering strict measures under the Graded Response Action Plan (GRAP).

The Commission for Air Quality Management (CAQM) anticipates a decline in pollutant levels due to stronger winds starting Thursday. The AQI is expected to return to the very poor category. After reviewing the situation, the CAQM's sub-committee decided to monitor conditions closely before implementing Stage-III of GRAP and will reassess on Thursday.

Severe Air Quality and Potential Restrictions

If Delhi's air quality remains severe on Thursday, authorities might enforce restrictions under GRAP's third stage. This could include bans on construction activities and certain vehicles. The Central Pollution Control Board (CPCB) data showed that 30 out of 36 monitoring stations in Delhi recorded severe air quality.

Bihar's Hajipur had the second-worst AQI reading at 417. An AQI between zero and 50 is good, 51 to 100 satisfactory, 101 to 200 moderate, 201 to 300 poor, 301 to 400 very poor, and above 400 severe. In January, Delhi's AQI was severe for three days: January 14 (447), January 24 (409), and January 26 (409).

Pollution Sources and Health Risks

According to the Centre's Decision Support System for Air Quality Management, vehicular emissions were the top pollution source on Wednesday, contributing 13.3%. Other significant pollutants included PM2.5 and PM10 particles. PM2.5 are fine particles that can penetrate deep into lungs and enter the bloodstream, posing serious health risks.

PM10 particles are coarser but can still irritate airways and worsen respiratory issues. Long-term exposure increases heart disease risk. CPCB data indicates Delhi's annual average PM10 and PM2.5 levels rose by 5% and 7% respectively from January 1 to November 12 compared to last year.

Impact on Health and Visibility

L M Darlong from Rajiv Gandhi Cancer Institute highlighted that prolonged exposure to PM2.5 significantly raises lung cancer risk. "These fine particles can trigger mutations in lung cells," he said. Early detection is crucial as symptoms like persistent cough appear late, complicating treatment.

The dense fog also caused visibility issues at Delhi airport, dropping to zero metres in the morning. This climate shift led to some flight diversions due to low visibility. At Indira Gandhi International Airport, visibility varied between 125 metres and 500 metres at different locations.

Weather Forecast and Future Outlook

The India Meteorological Department (IMD) reported very dense fog forming around 5:30 am, covering parts of Delhi with a thick haze by morning. Visibility dropped to as low as 125 metres in some areas. The IMD forecasts a clear sky for Thursday with northwest winds at less than six kmph in the morning.

Wind speeds are expected to increase slightly in the afternoon before decreasing again in the evening and night. Smog or dense fog is likely in the morning, with mist or moderate fog anticipated later in the day.

Delhi's air quality challenges highlight ongoing pollution issues affecting health and daily life. Authorities continue monitoring conditions closely while considering necessary actions to mitigate risks.