Delhi records lowest October average AQI in eight years at 166

Delhi's average air quality index (AQI) for October 2026 was 166, the lowest October average in eight years, the Union Ministry of Environment, Forest and Climate Change said in a statement released on Saturday, October 31, 2026. The figure compares with 223 in October 2025 and 269 in October 2018, the worst of the eight years. The ministry said the capital also recorded 220 days in the "Good to Moderate" categories between January and October, the highest for that period since 2018 apart from 2020, while the January-October average AQI fell to 167 from 170 a year earlier.

October is when Delhi's air usually turns. Winds slow down, temperatures drop, and smoke from crop-residue burning in neighbouring states, festival firecrackers, vehicle exhaust and construction dust collect over the city. An October average of 166 keeps the month, on average, inside the "Moderate" band, which on India's scale runs up to 200. In five of the previous seven years, the October average was above 200, in the "Poor" band.

The numbers matter for health. Fine particles known as PM2.5 are small enough to enter deep into the lungs and the bloodstream, and long exposure is linked to heart and lung disease. A cleaner October means fewer days when children, older people and those with asthma or heart conditions are exposed to the worst air. The ministry's count of 220 "Good to Moderate" days by the end of October is a measure people can feel in daily life: more days when walking, running or sending children to play outside carries less risk.

There is a caution, though. A monthly average can hide bad days, and Delhi's worst air usually arrives in November and December. The Graded Response Action Plan (GRAP) Stage 1 was already imposed in Delhi-NCR in October as the AQI crossed into the "Poor" range on some days. The real test of whether the improvement holds will come in the next eight weeks.

Rows show selected years from the ministry's eight-year series.

The ministry's statement reports the improvement but does not by itself show which measures produced it, so the reasons are likely to be debated as winter arrives and the city's anti-pollution plans are tested.

Short-term: The better October gives residents some relief going into November, but GRAP measures stay in force and can be tightened if the AQI worsens. Daily AQI should still be checked before outdoor exercise, especially by people with breathing or heart conditions.

Long-term: If the trend continues through winter, 2026 could become one of Delhi's cleaner years on record since 2018, and the data will be used to judge whether current anti-pollution measures are working and should be expanded.

Who is affected: Delhi's residents, especially children, older people and those with asthma, lung or heart disease; schools and outdoor workers; and the Delhi government, the Commission for Air Quality Management and neighbouring states.

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