According to the Central Pollution Control Board (CPCB), dust pollution, which includes various particulate matter like PM 10, PM 2.5 and PM 1.0, shot up to 261 micrograms per metre cube again last year.

Such levels were last found in 2010, during the Commonwealth Games. “Thereafter, over the next five years (till 2015), it (dust pollution) remained almost in the same range,” said D Saha, head of the air quality laboratory of CPCB.

The alarm bell was set off last year when the World Health Organisation placed the city on the top of a list of the dustiest megacities in the world.

While Cairo and Dhaka notched the second and third positions, Kolkata and Mumbai were placed fourth and fifth.

Now, the latest CPCB data also suggests that the rate of increase in dust pollution is higher compared to that of other pollutants such as SO2 and NO2.

Experts said the level of particulate matter in the air rises primarily because of construction activities, road dust and waste burning.

Saha noted that in 2010, the levels had hit 261 micrograms per metre cube from 153 micrograms per metre cube in 2006.

Vivek Chattopadhyay, senior program manager (air pollution control wing) of Centre for Science and Environment, attributed this rise to the construction activities during the Commonwealth Games.

He rued the lack of a regular study to ascertain why this dust pollution is shooting up or plummeting every year.

Jump in Construction & Vehicles

Scientists have attributed several reasons behind the jump, including unbridled construction activities, increase in number of vehicles and poor soil management, besides factors such as burning of waste.

“In 2005, around 600 building plans were sanctioned,” said a senior North Delhi Municipal Corporation official, requesting anonymity.

“In 2016, the three civic bodies together sanctioned around 3,600 plans,” he said, asking, “Now add to this the illegal constructions.”

Other construction activities such as roads, their widening, flyovers, Metro, have also increased over the years, along with the number of vehicles, aggravating the dust pollution in the city.

The Economic Survey of Delhi 2015-16 reveals that number of vehicles per 1,000 people has shot up from 317 in 2005-06 to around 530 in 2015-16.

The road network has increased from 32,131 km in 2007-08 to 33,868 km in 2015-16. Nearly 62 km of flyovers have been added between 2014 and 2016.

Thin on Green

Experts claimed that even though the green cover of Delhi has increased from 20.08% in 2013 to 20.22% in 2015, the rise has been specific in south Delhi and Lutyens’ Delhi area. Most parts of Delhi don’t have even an iota of green cover. This barren soil bereft of any grass cover becomes a major source of dust pollution.

“Soil texture is governed by small and micro organisms that live in the soil. But due to poor soil management and unbridled human activities, we are losing these organisms. As a result the texture is changing. We now have more lose dust, and every time wind blows, we have dust pollution,” said eminent ecologist Prof CR Babu, who heads the Centre for Environmental Management of Degraded Ecosystem.

An IIT Kanpur study submitted to the Delhi government in January 2016 suggests that PM10 particles mostly (40%) comprise particles such as Silicon, Aluminium, Iron and Calcium during the summer.

“This suggests that soil, road dust and airborne fly ash are the major sources of PM10 pollution in summer. In winter, however, it is the secondary particles which comprise most of the PM10 pollution,” said Prof Mukesh Sharma of IIT Kanpur who conducted the study.

Another reason attributed behind this drastic rise in PM10 levels is that a significant portion of gases such as SO2 also converts into secondary particles which adds to the PM10 pollution.

Experts claimed that while the reduction of SO2 has been possible because of a gradual shift to cleaner fuels and shutting down of thermal power plants, the NO2 level is constantly on the rise with the rise in number of vehicles and ‘dieselisation’.

Health Affected

With rise in particulate matter in the air, the risk of lung diseases and cardiac ailments are also rising in the city.

“Over the years, the number of patients with lung and respiratory diseases are on the rise. Cases of COPD, asthma and lung fibrosis have increased. Also on the rise are patients with cardiac problems because increase in particulate matter can affect our cardiac system both directly and indirectly,” said Dr Vikas Maurya, senior consultant and head of pulmonology division at Fortis Hospital in Shalimar Bagh.

Interestingly, the PM10 level plummeted between 2000 and 2006. Experts claimed that the Supreme Court directive of July 28, 1998 catalysed first-generation reforms in Delhi.

This helped improve emission standards for vehicles, implement the largest-ever public transport strategy on CNG, cap the age of commercial vehicles, improve the vehicle inspection programme and divert substantial truck traffic.

“But after 2007, only a few steps were taken — the Metro network was expanded, the number of buses was moderately increased, Euro IV emission standards were imposed and a small network of cycle tracks and footpaths were built around Commonwealth Games venues. This is too little too late. The air quality gains from the first-generation action have been reversed,” said Anumita Roychowdhury executive director (research and advocacy) of Centre for Science and Environment.