Before Pollution Spikes in Delhi, This Scientist Helps Give Officials 72 Hours to Prepare

India’s Air Quality Early Warning System, or AQEWS, predicts how Delhi’s air quality may change before severe pollution arrives. It focuses especially on extreme pollution episodes and includes pollutants such as fine particulate matter, or PM2.5. This matters because advance information can help authorities respond before the haze and health risks intensify.

The system combines ground-monitoring data, satellite information, weather forecasts and estimates of emissions from vehicles, industries, construction and crop-residue burning. Computer models then simulate how pollutants may move, react and accumulate over the following days. Weather conditions, especially weak winds and limited atmospheric mixing, strongly affect the result.

AQEWS was launched in October 2018. It can warn officials up to 72 hours in advance, although forecasts do not remove pollution themselves. Their value depends on how effectively authorities use the warning and reduce emissions through measures such as those under GRAP.

India’s Air Quality Early Warning System can forecast extreme pollution events in Delhi up to 72 hours ahead. This is roughly three days of advance notice. The timing matters because authorities can act before pollution reaches dangerous or highly uncomfortable levels, rather than waiting until the city is already covered by haze.

The system uses weather forecasts, monitoring-station observations, satellite information and emissions estimates. Its computer models calculate how pollutants could move, react and build up under expected atmospheric conditions. Weak winds and an atmosphere that limits dispersion can make pollution accumulate near the ground, so these factors are central to the forecast.

AQEWS was launched in October 2018. The warning does not guarantee clear skies or eliminate pollution. Instead, it gives officials time to consider steps under the Graded Response Action Plan, including restricting construction or curbing certain industrial operations.

Dr Sachin Ghude is a scientist at the Indian Institute of Tropical Meteorology in Pune. He has played a leading role in developing India’s Air Quality Early Warning System. His research connects atmospheric chemistry and air-quality modelling with questions involving human health, vegetation and climate.

The system was developed through collaboration among IITM, the India Meteorological Department and the National Centre for Medium Range Weather Forecasting. Together, these institutions contribute scientific knowledge, observations, weather information and modelling capabilities. Their work supports forecasts of how pollution may develop over the next three days.

This collaboration matters because air pollution has several sources and is strongly affected by weather. The system helps authorities predict extreme pollution events in Delhi up to 72 hours ahead. More recently, IITM has also implemented a 400-metre-resolution operational forecasting model for Delhi, allowing more local detail than a single city-wide average.

AQEWS works by bringing together information that describes both pollution sources and atmospheric conditions. Ground-based monitoring stations show current air quality, while satellites provide broader information. Weather forecasts indicate wind and atmospheric behaviour, and emissions estimates represent pollution from vehicles, industry, construction and crop-residue burning.

Advanced computer models process these inputs together. They simulate how pollutants may move through the atmosphere, react with other substances and accumulate near the ground. If winds are weak or the atmosphere prevents dispersion, the models can show that pollution is likely to build up. The system then forecasts air quality, including PM2.5 levels.

This approach is more useful than relying on one measurement or one source alone. IITM has implemented a Delhi model operating at 400 metres resolution, which can capture local differences more closely than a single city-wide average. The forecast still depends on the quality of data and how authorities use it.

When winds are weak and the atmosphere prevents pollutants from dispersing, emissions remain concentrated near the ground. Instead of being carried away or diluted, pollution can accumulate over the city. This can make the air feel heavy, cause eye irritation and contribute to the grey haze familiar during Delhi’s pollution season.

The effect involves both emissions and weather. Vehicle exhaust, industrial emissions, construction dust and crop-residue burning add pollutants to the air. AQEWS combines emissions estimates with monitoring data, satellite information and weather forecasts. Its computer models then calculate how those pollutants may move, react and build up under the expected conditions.

This is why air-quality forecasting cannot focus only on pollution sources. The same emissions can produce different conditions depending on the atmosphere. Identifying likely accumulation gives officials advance warning and helps them consider measures such as restricting construction or curbing certain industrial operations under GRAP.

When AQEWS predicts that Delhi’s air quality is about to worsen, authorities can prepare measures under the Graded Response Action Plan, or GRAP. Possible actions include restricting construction activities and curbing certain industrial operations. The warning gives officials time to organise these responses before pollution levels rise sharply.

The system’s forecast is based on expected emissions and atmospheric behaviour. It considers pollution from vehicles, industry, construction and crop-residue burning, then models how weather conditions may cause pollutants to move or accumulate. Weak winds and limited dispersion can signal that pollution will remain concentrated near the ground.

These actions are not automatic solutions to the entire problem. The article explains that forecasts do not eliminate pollution by themselves. Their effectiveness depends on how authorities use the information and how successfully they tackle emission sources. Early warnings make air-quality management more prepared and targeted instead of purely reactive.

PM2.5 is fine particulate matter, one of the pollutants included in India’s Air Quality Early Warning System forecasts. The article highlights it because these tiny particles can penetrate deep into the lungs. That makes PM2.5 especially important when assessing the air people are about to breathe during severe pollution episodes.

AQEWS estimates how PM2.5 and other pollutants may move, react and accumulate. It uses observations from monitoring stations, satellite information, weather forecasts and emissions estimates. Computer models combine these inputs to predict changes over the next three days. Weak winds and atmospheric conditions that limit dispersion can leave particles concentrated near the ground.

The system does not remove PM2.5 or guarantee clean air. Instead, it gives authorities up to 72 hours to prepare possible interventions under GRAP. Its health value therefore depends on using the forecast to address pollution sources and reduce exposure when worsening air quality is expected.