Airsheds: Why Cities Can't Clean Air Alone

Why pollution crosses city and state boundaries, how the Indo-Gangetic Plain forms one airshed, and why regional bodies like the Commission for Air Quality Management matter.

Air doesn’t respect boundaries.

Airsheds

An airshed is a region where air moves and mixes, sharing pollution.

The Indo-Gangetic Plain

Stretching from Punjab through UP and Bihar to West Bengal, it forms a large airshed.
Geography and weather trap pollution across the region.

Cross-boundary pollution

Studies suggest a large share of a city’s pollution, often half or more, can come from outside its limits.

Governance

The Commission for Air Quality Management (CAQM) was set up in 2020-21 for Delhi-NCR and adjoining areas, coordinating across states.
Most pollution rules are enforced by state pollution control boards.

Coordination problems

States may not act on pollution that mainly harms neighbours, a free-rider problem.
Political differences between states complicate cooperation.

Lesson

Clean air needs regional planning and cooperation.

The borrowed pollution

On many winter days, much of Delhi's pollution comes from outside the city, making Delhi-only measures insufficient.

Thinking each city can clean its own air

Much pollution comes from outside city limits.

Key takeaways

Airsheds share pollution across boundaries.
The Indo-Gangetic Plain is one large airshed.
Half or more of a city's pollution can come from outside.
CAQM coordinates across Delhi-NCR states.