The air quality index (AQI) in Delhi continued to soar past the 500 mark for the second consecutive day as the government grappled in formulating a coherent response. What is worse is that the early warning systems (EWS) that are supposed to track and identify the sources of air pollution are learnt to have failed in aiding the authorities.
As a consequence of the failure of these systems, forecasts about deteriorating air quality in the national capital have been far from accurate and residents are unable to plan their outdoor activities.
A senior scientist involved with the EWS informed Down to Earth (DTE) on the condition of anonymity that the model currently used to identify air pollution is failing to provide accurate information.
Interestingly, the EWS which is operated by the Union Ministry of Earth Sciences, had forecasted that today, on November 19, pollution levels of particulate matter in several parts of Delhi will not only be normalised but the air quality will improve from emergency levels and subside to the general category.
The Decision Support System (DSS) used by Indian Institute of Tropical Meteorology (IITM) is also employed to devise immediate pollution control plans. This DSS not only provides information about the sources of pollution but also forecasts the situation for the next five days.
The forecasts about the air quality improving overnight in Delhi is startling, but not at all reliable. This is because the model used in the DSS for forecasting is underestimating the pollution levels.
A senior scientist from the IITM, told DTE on the condition of anonymity that nearly 50 per cent of the sources of emissions have not yet been identified. This makes it difficult to make accurate predictions of hazardous pollution in Delhi.
The scientist further explained that, for instance, on November 12, 2024, there were about 50,000 weddings in Delhi, and the emissions from the fireworks were not accounted for in the model.
There are many other emission sources like this that have not yet been incorporated into the model. As a result, the model is unable to accurately detect air pollution and is underestimating it.
Underestimating pollution levels actually creates a much bigger problem.
IITM uses the Weather Research and Forecasting-Chemistry Model (WRF-Chem) to gather pollution data. This is a special type of atmospheric model developed to understand and forecast both weather and air quality.
IITM scientists explained that the model studies seven chemical and physical processes in the atmosphere. For example, it predicts the wind direction and the types of emissions that it will carry.
However, the issue right now is that they do not have fire count data. They are relying on fire count data from Indian Agricultural Research Institute (IARI).
Additionally, they cannot predict how many fires and what types of burning will occur the next day. If fire data is more accurate in the future, more precise information about air pollution can be provided.
Meanwhile, yesterday on November 18, the Supreme Court also reprimanded the government for failing to implement timely and strict measures under the Graded Response Action Plan (GRAP), despite hazardous pollution conditions. The court also ordered that if the AQI drops below 450, Stage 4 of the GRAP should not be discontinued without consulting the court.
In any case, although IITM’s model is failing to provide accurate and reliable information on air pollution, and is offering predictions with lower accuracy, IITM scientists are estimating that Delhi’s air will remain in the ‘severe’ category for the next three days.
This means there is no respite from the smog. Children and the elderly are advised to stay indoors.