Measuring Air Quality: AQI and Monitors

How India's Air Quality Index turns pollutant readings into categories, why monitoring stations are unevenly spread, and how low-cost sensors and satellites help.

You can’t manage what you don’t measure.

The AQI

India launched a National Air Quality Index in 2015.
It combines readings of pollutants like PM2.5, PM10, ozone and nitrogen dioxide.
Categories: Good (0-50), Satisfactory, Moderate, Poor, Very Poor and Severe (above 400).

Monitoring stations

Continuous monitoring stations are concentrated in big cities.
Many towns and rural areas have few or none.

Low-cost sensors

Cheaper sensors can fill gaps, though they’re less accurate.

Satellites

Satellite data help estimate pollution where there are no monitors and track stubble fires.

Information matters

Public AQI apps raise awareness.
Research shows that information can change behaviour, like people buying masks and purifiers.

Data gaps

Where pollution isn’t measured, it’s often ignored in policy.

The AQI app

A parent in Lucknow checks the AQI app each morning and keeps her asthmatic child indoors on "very poor" days.

Thinking pollution is well measured everywhere

Many towns and villages lack monitors.

Key takeaways

India's AQI launched in 2015.
It combines several pollutants into categories.
Monitors are concentrated in big cities.
Sensors and satellites help fill gaps.