Explore the reasons why Delhi faces such high amounts of air pollution – and what can be done to tackle this environmental crisis
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Of the world’s 30 most air-polluted cities, 21 are located in India. But one city in particular has made headlines time and time again for its startling pollution: Delhi.
Last year, Delhi’s air pollution levels reached an all-time high: 36 times greater than the safe threshold outlined by the World Health Organisation. And annually, 11.5 per cent of all deaths in the city – more than one in 10 – are caused by air pollution.
So, what is making the city’s air quality so low – and crucially dangerous for its population of more than 33 million? Here we run through the major reasons explaining Delhi’s pollution.
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Human-caused activities
A plethora of human-caused activities drive Delhi’s pollution. The city has many coal power plants – 12 within a 300-kilometre radius – which release swathes of harmful pollutants during their operations. These include sulphur dioxide, nitrogen oxides and soot – all of which contribute toward worsening respiratory health.
Vehicular emissions are also a major source of pollution in the city: an estimated 1.1 million vehicles enter and exit Delhi each day.
Additionally, heavy construction in Delhi – and the dust it produces – contributes to the city’s pollution, along with landfills. The three landfills in the city – Bhalswa, Ghazipur and Okhla – have collectively cost Delhi almost $57 million in environmental damage.
Yet, despite all three reaching capacity, waste is dropped off at them every single day. As such, when landfill fires occur, larger amounts of waste are set alight and produce much greater air pollution.
Another significant and detrimental activity to Delhi’s air quality is stubble burning: the practice of farmers setting fire to leftover plant stalks following harvest. The reason why farmers do this is to clear the soil for future crops to be planted, and it isn’t an activity exclusive to Delhi.
Across the entirety of northern India, it is estimated that farmers burn around 23 million tonnes of paddy stubble each year, although it is currently illegal. Incentives, such as financial rewards, have been offered to farmers who do not partake in stubble burning, but some reports suggest farmers never received the financial contributions expected after abstaining from the practice.
Winter
Year round, Delhi’s air quality is extremely poor, but becomes particularly dangerous during the winter months. Data shows that the city’s levels of PM2.5 – a type of air pollution made of tiny droplets and particles – are 59 per cent higher in winter compared to summer.
That’s because during cooler periods, a weather phenomenon known as ‘temperature inversion’ occurs, where cool winter air forms a layer near the ground and traps pollutants, preventing them from dispersing. As such, these harmful chemicals are concentrated into smaller areas. Additionally, urban structures within Delhi – such as tall buildings – compromise the ability of air to circulate, further exacerbating pollutant levels for those on the ground.
Between December and February, cooler surface temperatures also allow fog to form, which combines with atmospheric pollutants to form smog. Blankets of this heavy and thick toxic air wreak havoc not only on citizens’ lives and health but also disrupt flights and turn horizons into indiscernible haze.
The city’s geography and weather
Another factor exacerbating Delhi’s pollution levels is its geography. Located in the Indo-Gangetic Plain of Northern India, New Delhi is bordered by the Himalayas which form a barrier, preventing air from dissipating.
A lack of strong winds also make it difficult for air to move around – and consequently particulate matter to be dispersed.
How can Delhi’s air pollution be tackled?
The problem of air pollution in Delhi is a complex one; and governments have begun to make inroads to prevent the issue spiralling out of control. Vehicle emissions standards have increased in recent years, helping to minimise pollution caused by transport. In addition, the closure of two coal power stations in the city contributed toward the reduction of particulates released from coal combustion. Delhi have also begun to implement anti-smog guns – ‘guns’ that spray water into the air to reduce pollution, often attached to trucks – although their effectiveness is not fully understood.
Future policies to tackle air pollution on a city-level include covering materials on construction sites to prevent dust blowing in the air, along with planting more trees, restricting waste burning and replacing coal with wind and solar. As more of these can be fulfilled, it is almost certain Delhi will see its rising pollution levels begin to fall.
However, some call for further expansive preventative efforts that involve the whole of the Indo-Gangetic plains, where Delhi is located. Because particulate matter can travel across cities via wind, tackling the air pollution of many cities at once will consequently help to reduce Delhi’s air quality.
In particular, one approach involves the implementation of fixed seasonal policies across cities. These may include imposing restrictions on construction (as building dust contributes toward air pollution) when temperature inversions are predicted.
Strengthened air quality and meteorological monitoring may also allow officials to create targeted warnings even days prior to visible pollution.
