Via The Guardian: Delhi's deadly dust: how construction sites are choking the city. Excerpt:
Far out on Delhi’s southern and eastern fringes the rows of high-rises suddenly turn skeletal. The population of the Indian capital, already the second largest in the world, is forecast to grow by 9 million in the next 15 years; and despite a recent lull in new projects, areas such as Noida are a universe of worksites, cranes and workers.
The empty towers stretch as far as can be seen – which is only about 300 metres. Like much of Delhi on most winter mornings, Noida is blanketed in thick smog and a heavy dust that cakes windows and clogs throats.
A comprehensive 2016 study of what is to blame for Delhi’s poor air identified some obvious sources, such as car emissions, the city’s coal-fired power stations and rubbish fires both small and literally mountainous. But it also highlighted more unlikely culprits.
Dust kicked up by cars along Delhi’s vast and growing road network contributes between a third and 56% of the most harmful pollutants in the city’s atmosphere.
The city’s construction sites, and the production of the raw materials that feed them – such as bricks and concrete – are also an outsized contributor to the foul air that some lung specialists warn is making Delhi hazardous, particularly for children and the elderly.
In a country largely under construction – by some rough projections, around 70% of the buildings that will exist in India’s cities by 2030 are yet to be built – controlling the dust produced by roads and worksites is an important, but largely neglected, part of clearing Delhi’s air, according to environmental groups.
Landlocked by treeless plains and deserts, Delhi is inherently dusty. “It’s one of the reasons we can’t have air quality standards as strict or high as the US,” says Sarath Guttikunda, the founder of UrbanEmissions, an air pollution research group. “Our annual standard for PM2.5 pollutants is 40 units, but the World Health Organization’s guideline is 10.”
As of 5:00 a.m. Thursday local time, Delhi air quality index stations are reporting PM2.5 counts ranging from 171 (unhealthy) to 332 (hazardous).