Breathless in Mumbai: Climate Change Has Made It Harder to Breathe in Mumbai

Why in News?

• Among Indian metro cities, Delhi gets the most attention for its notoriously high pollution levels. But it has been evident for some time now that bad air problems affect large parts of the country.
• The winter deterioration in air quality in Mumbai is fast becoming an annual talking point, just like it has been in Delhi for the past decade. 

Current Situation of Mumbai’s Air Quality

• For most of October, the Air Quality Index (AQI) in Mumbai has registered moderate or poor. The city has not had a single good air day this month.
• In the first few days of this month, the pollution was much more intense than what the AQI indicated because a layer of haze blanketed major parts of the Mumbai sky, leading to reduced visibility.
• However, there is a thin silver lining; the basket of pollutants is dominated by coarser particles which can cause irritation but are less harmful than finer particles like PM2.5.

Mumbai’s Geographical Advantage: Natural Cleaning Mechanism

• The coastal city has a natural cleaning mechanism. Strong surface winds (moving from the land towards the sea)lead to faster dispersal of pollutants, and the strong sea breeze (moving from the sea towards the land) sweeps away these particles from the land.
• This wind reversal cycle is a feature of the city for most parts of the year and repeats every three to four days during this time of the year.
• When the wind is directed towards the sea, the dust particles get swept away. This acts as a natural cleansing mechanism.

Reasons Behind Mumbai’s Worsening Air Quality Despite Natural Cleaning Mechanism

• Unfavourable Meteorological Conditions
  • Meteorological conditions play a role in pollution. But it should be clear that the weather or climate cannot generate air pollution.
  • Air quality deteriorates mainly due to anthropogenic sources of emissions, whether local or distant. Meteorological conditions only help to manoeuvre the pollutants in the air.
• Due to La Nina- A Climate Change Phenomenon
  • Last winter Mumbai experienced record-breaking particulate pollution which was largely related to the unusual triple dip La Nina conditions which is linked to climate change.
  • An abnormal drop in surface temperature in the Pacific Ocean had a significant effect on coastal wind speeds around Mumbai.
  • There was hardly any wind reversal from across the Arabian Sea, which would otherwise occur every two to three days and disperse pollutants in the air.
  • In other words, the emission from various anthropogenic sources was not cleaned up and the city experienced its worst air of the decade.
• Delayed Withdrawal of Monsoon
  • La Nina has gone this year. However, the withdrawal of the monsoon was delayed till October.
  • Things get complicated in the city if the withdrawal of the monsoon is delayed. The withdrawal time of monsoon always plays a critical role in Mumbai’s air quality.
  • The withdrawal is always followed by an anticyclonic circulation that was right above Mumbai and the surrounding regions during the initial days of October.
  • This led to weak ventilation in the city. In recent years, the city has witnessed some strong and longer spells of bad air quality, that defies the basic scientific understanding of a usual environment.
• Disruption in Mumbai’s Wind Patterns
  • Sometimes, when the wind cycle gets temporarily disrupted for some reason, it has an impact on the city’s air quality.
  • The last two years have shown that this geographical advantage no longer offers reliable protection.
  • Last year saw the longest spell of poor air quality in the city, extending from November to January. On some days, Mumbai’s air was more polluted than Delhi.
  • The transport level winds, much above the surface in the atmosphere, were moderately fast and were blowing towards Mumbai from Lonavala and Khandala in the Sahyadri ranges, around 2,040 ft above sea level.
  • These chilly moderate winds are capable of transporting pollutants towards Mumbai.
• Dust Emissions
  • The fact that PM10 continues to be the major pollutant in the city and the visibility of Mumbai’s residents has been impacted.
  • It suggests that the major blame for the current worsening of air quality should be ascribed to coarser particles, largely a result of dust emissions.
  • Many development and construction activities undertaken across the city include the coastal corridor, work on the Metro and other digging activities.
  • Unfavourable weather conditions exploit the emissions from such sources to create pollution.

 Way Forward

• Long-Term Mitigation Planning
  • The festival season this year will reach its peak around mid-November when winter will set in. It would be a concern if the festivities lead to an increase in emissions. However, that would still be a short-term issue, lasting for two or three days.
  • The government needs to prioritise long-term mitigation planning based on mapping airsheds areas where pollutants get trapped because climate change is leading to extreme and unusual weather events and precipitating changes in the ecosystem.
• Address the Root Cause of the Problem
  • India’s Coastal regions are highly vulnerable and hence, Mumbai needs to be extra-attentive.
  • There is a need to address the root cause of the problem which is anthropogenic emissions from the source.
  • Understanding and Accepting the Problem Using Scientific Data
  • The battle against air pollution could prove long and difficult, but it should be addressed using science.
  • Understanding and accepting the problem is half the solution. There is a need to own the data coming from reliable scientific sources rather than living in denial. 
• Implementation of Short- and Medium-Term Solutions
  • Cordoning off construction sites with green curtains, regular spraying of water to dampen dust particles and prevent them from becoming airborne, faster implementation of fossil fuel-less transportation and ensuring smooth traffic flow check pollution in the short-term.
  • Transitioning to electric vehicles, addressing solid waste management, cleaning up dumping grounds and industrial toxin management can improve air quality in the medium term. 

Conclusion

• In March this year, the BMC had released Mumbai Air Pollution Mitigation Plan (MAPMP) guidelines that laid down procedures to be followed during construction and other activities that cause dust and pollution.
• The geographical advantage of Mumbai has protected the city from bad air quality but due to climate change the protection is diminishing.
• Given the seriousness of climate change, no time should be lost in bringing about these effective measures to improve the city’s air quality.

Q1) What is air pollution and its causes and effects?

It is the contamination of air by harmful gases, dust and smoke which affects plants, animals and humans drastically. There is a certain percentage of gases present in the atmosphere. An increase or decrease in the composition of these gases is harmful to survival.

Q2) What is the difference between PM2.5 and PM10 particles?

Dust from roads, farms, dry riverbeds, construction sites, and mines are types of PM₁₀. Coarse (bigger) particles, called PM₁₀, can irritate eyes, nose, and throat. Fine (smaller) particles, called PM_2.5, are more dangerous because they can get into the deep parts of lungs or even into blood. 

Source: The Indian Express