Dr Gufran Beig, founder project director, safar, chair prof NIAS, IISc Dr Gufran Beig, Founder Project Director, System of Air Quality and Weather Forecasting And Research (SAFAR) & Chair Professor NIAS, IISc, speaks to Omkar Gokhale on Mumbai’s deteriorating AQI, the contributing factors and what can be done about it.
Why is Air Quality Index (AQI) so bad this year and what are the contributing factors?
The accumulation of suspended fine particulate matter in the air post-Diwali was high due to calm wind conditions which prevailed in Mumbai. The Southwest monsoon has just withdrawn from Mumbai. After the withdrawal of monsoon, anti-cyclonic circulation prevails, which lead to stagnant wind speed. In addition to this, Cyclone Sitrang, which formed in the Bay of Bengal, also contributed to slowing the wind speed on October 24. People celebrated Diwali with much vigour this year. Hence, with additional emissions due to burning of firecrackers, AQI shot up to ‘very poor’ category. However, it quickly recovered. Increased windspeed has led to improved AQI in Mumbai in the last two days. Due to heavy rain in the past two years in Mumbai, all pollutants got washed away and Mumbai observed “satisfactory” AQI in 2020 and 2021. However, this year, with the monsoon withdrawing earlier and no rain during Diwali, the pollutants were not washed away.
Is climate change affecting the AQI of Mumbai and what are the factors leading to deteriorating AQI in the city for the last few years?
While the change in AQI is a day-to-day phenomenon, climate change refers to long-term, say decadal change. In all likelihood, climate change is responsible for unprecedented extreme pollution events, which are weather-related and sometimes related to large-scale systems. In 2022 itself, there were three back-to-back duststorms in the month of January and February originating in the Gulf region and Thar desert. It was unusual as duststorms normally do not occur during winter as the air is still heavy. Ongoing westerly disturbances pushed most of the dust to Mumbai, affecting its AQI. If you refer to air quality data of SAFAR for the last seven years from 2015, you will see only a marginal change in the AQI. However, extreme pollution events are increasing. While overall air quality might remain the same, pollution is too high on certain days because of slow wind trapping pollutants in the air and is extremely low on some days due to heavy rains, which wash away the pollutants. Mumbai also recorded the lowest AQI during the monsoon this year. Extreme events are averaging out each other. However, it is of concern as it does not give the exact idea of impact on the environment.
Are construction of infrastructure projects in the city affecting the air quality?
Large number of infrastructure projects create dust and it majorly contributes to the quantity of bigger particles, including PM 10. Contribution of dust to smaller particles like PM 2.5 is relatively less. There are excavations going on for such projects and such work impacts air quality related to PM 10 and increasing pollution in the city.
Interestingly, the level of biofuel emissions due to the use of coal and wood for cooking and water heating in the city’s slums has increased since last year. While it declined after the Ujjwala scheme was introduced, due to economic issues and other reasons, the slum population has resorted back to quick food-cooking measures leading to increased emission of biofuels, which contributes to the quantity of PM 2.5 in the air.
As per a SAFAR sample survey of 80 slum clusters in Mumbai having a population of 5 lakh, from around 40 per cent of slum residents using LPG, a 2018 survey found that the number of slum residents using LPG had increased to 85 per cent after the introduction of the Ujjwala scheme in 2016-17. However, updated data of 2021 revealed that 70 per cent slum population was consuming LPG and 30 per cent had resorted to the use of biofuel.
Mumbai is surrounded by sea on three sides, so surface windspeed is normally higher. There is also wind reversal now and then. When winds originate from the oceanic side, it is clean and it sweeps away all the city’s pollution leading to cleaner AQI but when it gets reversed, AQI deteriorates. This cycle continues for the whole year. Mumbai is blessed by this geography.
Is AQI affecting the quality of life of Mumbaikars and what are the likely health hazards and solutions?
The people of Mumbai are certainly likely to face the threat of health hazards, including respiratory system-related diseases, as humidity is high and there is a high level of toxicity in the air emissions. Since the pollutants are made up of different chemicals, the toxicity of pollutant particles differs from city to city. There is lot of water in the atmosphere due to humidity and particles emitted due to industry, vehicles and traffic jams make a toxic blend of toxins. Although the mass concentration of PM 2.5 particles in Mumbai is much lower than Delhi, Mumbai’s pollutants have more toxic elements than that in Delhi. If traffic jams can be prevented, improvement in AQI is bound to happen.
What are SAFAR’s initiatives for public awareness about impacts of low AQI and pollution?
SAFAR has started awareness programmes in many cities and focuses on workshops for schoolgoing children. School awareness programmes, in which the flag of a particular AQI prevailing on that day is put up, is being implemented in cities like Pune and Ahmedabad. Children are being made aware about advisories based on AQI forecasts and the impacts of climate change during morning assembly. If any school contacts us, we may launch such programmes in Mumbai as well. We are seeing changes in children’s mindsets after our awareness programmes. Parents conveyed to us that considering the impact of air and noise pollution, their children were voluntarily deciding not to burst firecrackers. There is a paradigm shift in approach and if children are made aware of the same, our cities will have a better future.