An unexpected perk of having a geographically dispersed newsroom is the casual weather updates that we exchange on news calls. As winter sets in, these are often replaced by updates on the air quality in different cities. Those of us from Delhi usually have a lot to contribute on the subject, from complaints about the sting in our eyes when we step outside to analyses of which N95 mask will get us through the season.

This year, however, colleagues visiting or settled in even coastal cities noticed that they had encountered high Air Quality Index readings in them.

To confirm, I checked the latest available data from across 249 cities in India, collected by the Central Pollution Control Board. The data showed that as of December 9, most major coastal cities were recording “moderate” AQI levels. Mumbai had an AQI of 115, Chennai 138, Mangaluru 140, Puducherry 124 and Sri Vijaya Puram (formerly Port Blair) in the Andaman and Nicobar Islands had an AQI of 121.

While these are significantly lower than the numbers a north Indian city such as Delhi sees, at these AQI levels, possible health impacts could include “breathing discomfort to the people with lungs, asthma and heart diseases”. On the same day, Visakhapatnam saw “poor” AQI, at 216.

Some seasonal factors could play a role in this pollution, since PM10 and PM2.5 levels are generally higher in winter than in summer and monsoon. In fact, the annual average AQI of some of these cities has fallen over the years. In the last 10 years, for instance, Chennai has seen a fall in average annual AQI from 114 to 74, and Mumbai from 110 to 83, a recent study by think-tank Climate Trend showed. Visakhapatnam, however, has seen an increase in average annual AQI from 98 in 2016 to 113 in 2025.

The study warns that though some cities have seen improvement, they “fail to reach consistently safe levels” of air and even show “regular oscillations indicating ongoing pollution pressures”. Improvement in annual averages also does not reflect possible increases in individual pollutants: for instance, one study shows that between 2015 and 2020, Chennai saw a “net increase” of PM10 by 4 micrograms per cubic metre.

The high AQI readings of coastal cities on specific days seemed surprising, given that they have the benefit of natural dispersal of pollutants at night, as a result of the land-sea breeze.

This breeze forms because land cools down at night, while warm air continues to rise over the sea. The resulting low pressure over the sea draws cooler land air out, which carries with it suspended dust and other pollutants.

So why was this natural flushing not helping?

A quick chat with Sarath Guttikunda, founder and director of UrbanEmissions, an open data source on air pollution trends and analysis, revealed a simple answer.

He explained that emissions are rising year after year in these cities, but the meteorological and geographical advantages they enjoy are limited, and are not seeing major changes. “If you would look at the meteorological patterns in 2000 and 2025, they will pretty much look the same”, said Guttikunda.

The natural next question is: what is the source of high emissions in these cities?

Very few studies look at pollution sources of India’s coastal cities. One such is from 2014, co-authored by Guttikunda, which showed that industrial activity was a major cause of pollution in some of these cities. Chennai and Visakhapatnam, for instance, are industrial hubs, and 21% of Chennai’s PM10 and 15% of Visakhapatnam’s came from coal, diesel and gas combustion.

The study also found that between 2011 and 2012, sulphur dioxide emission, from increasing industrial activity and consumption of coal, increased by at least 30% in both cities.

But rather than these “point sources”, the paper noted, a greater contribution came from “diffused sources” of pollution, such as vehicles and road dust, which are dispersed over a larger area. For instance, vehicle exhaust contributes 35% of Chennai’s PM10 levels and 23% of Visakhapatnam’s, according to the study.

The authors noted that much of this dispersed pollution is also linked to industrial activity. “While the growth of private vehicles has occurred at a rapid rate, major contributors to road transport emissions were the freight vehicles” that were running on diesel, to and fro from ports and industrial hubs, they wrote.

Meanwhile, Mumbai, as we had reported earlier, is plagued by a different diffused source – construction activity that has seen a boom in recent years.

The authors noted that these sources are of particular concern because emissions from them “are steadily increasing”.

Granular data over years for pollution levels is available in only limited cities and for limited time periods – thus getting a detailed picture of the shift in pollution in coastal cities remains a challenge. Annual AQI averages often do not capture the changes in spikes in emissions of different pollutants.

But data from individual days, and increases in emissions of particular pollutants over some years offer some clues. They suggest that while north India’s inland cities are well known to be the country’s most polluted, coastal cities may also no longer offer any escape.

Here is a summary of last week’s top stories.

The IndiGo crisis. The Directorate General of Civil Aviation removed four of its flight operations inspectors following the enormous disruption of IndiGo’s operations last week. The aviation regulator directed them to return to their parent organisations.

The officials had been working for the regulator on a contractual basis and were responsible for monitoring safety, pilot training and regulatory compliance.

On Tuesday, the Ministry of Civil Aviation directed the airline to cut its scheduled flights by 10% to stabilise its operations. IndiGo holds about 60% of India’s domestic civil aviation market, making it the country’s largest airline.

Indian railways is running trains for passengers hit by the IndiGo crisis. But they are going empty, writes Tabassum Barnagarwala.

Kerala sexual assault case. A trial court in Kerala acquitted Malayalam film actor Dileep in a 2017 case pertaining to the abduction and rape of an actor. He was acquitted of all offences after a nearly eight-year trial. However, the court found six other persons guilty of rape, conspiracy and abduction, among other offences. They were sentenced to 20 years of rigorous imprisonment.

On February 17, 2017, six men kidnapped and sexually assaulted an actor inside her car for two hours. They had allegedly also filmed the assault to blackmail the woman. Dileep was among the 10 persons accused in the case and was alleged to be the mastermind of the assault.

Goa nightclub fire. A Delhi court denied anticipatory bail to Saurabh Luthra and Gaurav Luthra, who allegedly fled India after a fire at their nightclub in Goa killed 25 persons. They were detained by the Thailand Police in Phuket at the request of the Indian government and the process of bringing them to India is underway.

Their lawyer told the court that they had not fled the country, but had gone to Thailand for business. However, the Goa government said that the Luthra brothers booked the flight at 1.17 am on December 7, shortly after the fire.

It also alleged that the brothers had no business interests in Thailand and that their family did not cooperate with the police when the officers went to their home.

The expensive fantasy of Goa displaces Goans and runs on cheap migrant labour, writes Kaustubh Naik.

Striking inequality. The top 1% of India’s population holds 40% of the wealth, making the country one of the most unequal in the world, according to the 2026 World Inequality Report. The richest 10% hold about 65% of the total wealth.

In terms of income inequality, the top 10% of earners receive about 58% of national income, while the bottom 50% get only 15%. According to the report, the income gap between the top 10% and the bottom 50% remained stable between 2014 and 2024.

Globally, wealth has reached historic highs, but remains “very unevenly distributed”. The top 0.001%, which is fewer than 60,000 multimillionaires, owns three times more wealth than the entire bottom 50% of humans put together, said the report.

Also on Scroll last week

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