How Delhi’s roads kick up a dust storm and make matters worse
Every day, Rajni Kumar’s four-year-old son Viren returns from school coughing. The 25-year-old mother blames the city’s poor air quality for it. As pollution levels in the Capital reach alarming levels, most people eco her concerns and rue the fact that little has been done to mitigate the problem.
While pollution from vehicles and industrial sources has is often discussed threadbare, an obvious and important culprit remains unattended — road dust.
“The major problem faced by Delhi is of particulate matter,” says Mukesh Sharma, a professor at IIT Kanpur and lead author of a study about the sources of air pollution. The study found that road dust makes up more than 50% of the total PM10 particles, that are 10 micrometres or less in diameter, and about 38% of PM 2.5 particles (that are 2.5 micrometres or less). PM10 and PM2.5 levels in Delhi regularly rise to five the times safety mark.
According to the US Environmental Protection Agency road dust is “earthen material or dirt that becomes airborne, primarily by the friction of tires moving on unpaved dirt roads and dust-covered paved roads”. With about 33,198km roads and nearly 97,04,741 registered vehicles, the wheels on the city’s poorly maintained roads grinds up a dust storm.
Delhi’s location and proximity to Rajasthan means there is a continuous inflow of dust carried by winds. The combination of these dust particles with pollutants from vehicles and industrial sources creates a deadly mix. Harmful aerosols from vehicular effluents and industrial sources cling on to the surface of dust particles and emissions that might otherwise be dispersed by winds linger by settling on these particles.
“When they come out they are very hot but once they are released they cool and condense around existing particles,” Sharma explained.
The city roads that also are hubs of economic activity turn into the cradle of pollution. Take for example, Hakima Khatun. The 51-year-old woman has a small shop at a busy intersection in west Delhi. She suffers from heavy wheezing due to the dust but says she cannot afford to think of moving.
“This is my livelihood, I cannot escape the dust and pollution,” says Hakima. Many others like Hakima, whose life and livelihood is linked to roads, say they do not have a choice.
Sharma, however, says that the man-made dust can be prevented. Maintaining roads and pavements and watering are some ways to keep the dust settled.
In April last year, CM Arvind Kejriwal announced a slew of measures including the vacuum cleaning of roads. However, the Public Works Department has only four operational vacuuming machines and attempts to sprinkle water using cranes were criticised by the National Green Tribunal for being ineffective.
The long term solution is to pave the roads and to plant grass and shrubs, says Anumita Roychowdhury, an executive director at the Centre for Science and Environment.