When London’s Great Smog of 1952 killed over 12,000 people, the world first realised that the deadly cocktail of air pollution and weather conditions could affect public health.
The term “smog” — a mixture of smoke and fog — entered our talks, marking the beginning of our understanding of the urban air pollution crisis.
Los Angeles followed with its distinctive photochemical smog in the 1970s due to automobile emissions reacting with sunlight, creating a yellowish haze that became a sign of the city’s rapid growth.
But Delhi’s smog, which gained global attention in 2016 when the air quality index crossed the 500 mark and schools were shut down for the first time, is a different story altogether.
Unlike London’s coal-driven smog or Los Angeles automotive exhaust, Delhi’s severe air quality emergency is a perfect storm of multiple factors: agricultural stubble burning in neighbouring states, vehicular emissions, construction dust, industrial pollution, and calm weather conditions of winter which trap these pollutants over the city.
What makes Delhi’s situation unique is its geography and the timing of the bad air quality episodes. Located in the Indo-Gangetic plain, the city becomes a bowl of pollution during winter months especially in November, trapping pollutants under a layer of cold air which is accounted to decrease in the layer of the atmosphere closest to the Earth’s surface.
When this combines with the seasonal stubble burning in the rice fields of neighbouring states, the result is catastrophic air quality. Being the most monitored city in India, Delhi’s AQI routinely crosses the 400 mark, while the WHO safe limit is 50.
But this demands a question. When it is already proven that the air quality of the city deteriorates every winter, why it is so difficult to reduce Delhi’s air pollution? The solutions must be as unique as the problem.
The Commission for Air Quality Management’s (CAQM) recent directives present a promising framework ranging from converting agricultural waste into economic opportunities through bioethanol and power generation facilities that could transform the stubble from a liability to an asset.
But Delhi needs a year-round strategy. The construction sector which is contributing significantly to PM2.5 and PM10 levels, requires a technological revolution such as a high-resolution air quality monitoring network at the construction site linked to automatic sprayers, mist cannons, or sprinklers that spray water over the area to reduce dust being taken up into the air. Real-time monitoring through web portals and mandatory dust control measures must become the norm, not the exception.
The suggestion of artificial rain as a “quick fix” for the air pollution crisis needs to be scientifically explored as it has the potential to pose long-term environmental risks.
The idea of “washing away” pollutants with artificial rain seems appealing, it may fail to address the root causes of air pollution and could inadvertently introduce new ecological challenges.
Additionally, cloud seeding requires specific meteorological conditions to be effective, which makes it an unreliable and inconsistent solution to the persistent pollution problem.
Rather than pursuing temporary and potentially harmful interventions, the focus should shift to strategies that address the root causes of pollution. These include improving industrial practices, promoting sustainable agriculture, and transitioning to cleaner transportation systems.
The success of the Delhi Metro shows that people will embrace clean alternatives when they’re efficient and accessible. But more needs to be done in the transportation sector.
Delhi’s millions of vehicles compete with multiple pollution sources for the position of number one polluter in the city. With a push toward electric vehicles being accelerated, we also need to put a cap on the number of vehicles a city can cater to.
Real-time pollution monitoring data from industrial units and construction sites should be mandatorily linked to their operating licenses, with automatic suspension triggered by consistent violations.
As we face another winter of discontent, it’s clear that Delhi’s battle for breath needs more than just emergency measures. The solutions exist - from bio-decomposers for crop residue to AI-powered construction dust monitoring - but they need political will and public support to succeed.
Dr Ravindra Khaiwal is a Professor of environmental health at the PGIMER, Chandigarh.