5 min readFeb 9, 2023 05:07 PM IST
First published on: Feb 9, 2023 at 05:07 PM IST
The past year was unprecedented for India in terms of environmental protection in many ways. India’s pledge to have net-zero emissions by 2070 was one of the most important moves towards its resolve to fight climate change. Anthropogenic emissions are central to environmental issues, whether climate change or air quality. During the peak winter months of November to January in 2022-23, air quality in India’s financial hub, Mumbai, noticeably deteriorated — a taste of what Delhi encounters frequently for Mumbaikars.
Out of the past 92 winter days, Mumbai observed 66 poor and very poor air quality days in 2022-23 as compared to just 28 in the past three years’ average. More so, it had just one day in the permissible limit (NAAQS) this year as against the average of 15 days in the recent past. So good days declined, but foul days have increased by a whopping 135 per cent, leaving residents more choked and breathless than they have been in years. On many days during these months, the air quality in Mumbai sank lower than in Delhi. These findings are from India’s first indigenously-developed forecasting framework, SAFAR, an initiative of the Union Ministry of Earth Sciences. It follows a robust and rigorous scientific methodology that conforms to sitting guidelines established by the World Meteorological Organisation. Mumbai is one of four cities in India that has air quality forecasting and advisory services, while other cities are yet to begin as mandated in NCAP. What caused this unusual development?
Air quality deteriorates mainly due to emissions from anthropogenic and natural sources, and weather manoeuvres. The weather or climate cannot generate emissions. Some cities like Delhi have a disadvantage due to their geographical location, being landlocked. But Mumbai is a coastal city that enjoys a natural cleansing advantage. Stronger surface winds favour faster dispersion and wind reversal cycles of strong sea breezes that sweep away air pollutants from the land. However, there have been indications in recent times that nature can take away the blessing it bestowed. Scientists have discovered that climate change is leading to extreme weather, changes in the ecosystem, and human displacements, but linkages with air quality remain elusive. The reason for the sudden spike in the current pollution cycle in Mumbai is part of a larger meteorological phenomenon that needs to be studied further. My research suggests that the unprecedented triple dip in La Nina, attributed to climate change, has played an unusual role.
This phenomenon has led to the change in wind patterns affecting Mumbai, with frequent calmer wind spells, and delayed cleaner sea wind reversal around the region. This, in turn, affects the natural cleansing mechanism of the city by reducing the dispersal rate of pollutants and trapping the newly generated high-flying dust emissions. The import of transboundary pollution from more polluted regions due to wind pattern changes is also adding to the misery. An increase in all sizes of particles (coarser and finer) has been observed. It is scientifically prudent to conclude that the major share in the current worsening of air quality is from dust emissions. Many redevelopment and construction projects are operational across the city. So, the increase is due to intensifying emissions at the source, which usually consist of PM 2.5 (Particulate Matter) – made up of transport (31 per cent), industries (20 per cent), and resuspended dust (15 per cent), besides other smaller sources.
Before we start to address the problem, we need to recognise it. The debate on relocating ambient air quality monitors in the city to cleaner or more polluted locations is merely a form of avoidance. After all, wherever they are located, a Mumbaikar is breathing foul air. Acting together and strengthening the fight against air pollution should be the order of the day. The situation is not currently urgent, but it is a clear early sign of the impact climate change can have. Hence, we must address the root cause of the problem — anthropogenic emissions — instead of looking for shortcuts.
The battle against air pollution is long and difficult, but success is achievable beyond doubt. Putting green curtains around construction sites, regularly sprinkling water on truck tyres and debris before loading and unloading material, and ensuring smooth traffic flow to overcome snarls are some of the immediate remedies. In the medium term, transitioning to electric vehicles, addressing solid waste management, dumping grounds, and industrial toxin management are some actions that will help us achieve better air quality.
The writer is Chair Professor, National Institute of Advanced Studies, Bangalore and Founder Project Director, SAFAR
The battle against air pollution is long and difficult, but success is achievable beyond doubt. (File) 
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