Swiss and Indian researchers solve mystery of New Delhi night smog
Smog in New Delhi even happens at night.
Keystone / Rajat Gupta
A team of Swiss and Indian researchers say they have found the reason why smog forms at night in the Indian capital New Delhi, contrary to all the rules of atmospheric chemistry.
This content was published on
1 minute
Keystone-SDA/jc
Português
pt
Pesquisadores suíços e indianos resolvem mistério do smog de Nova Deli
The trigger is the fumes from wood fires used by inhabitants for cooking and heating, according to a press releaseExternal link on Monday from Switzerland’s Paul Scherrer Institute (PSI). In the absence of strict regulations, plastics and other waste materials are also burned, releasing a gaseous mixture with countless chemical compounds, including cresol, a toxic aromatic compound. As night falls, the temperature in New Delhi drops rapidly. Some of these gaseous molecules then condense and within a few hours turn into fine particles that form a greyish vapour.
“The chemical processes that take place in the air at night are unique to the Indian capital and have not been observed anywhere else in the world,” says Imad El-Haddad, an atmospheric chemist at PSI and one of the study authors.
The findings, published in the journal Nature Geoscience, are the result of joint research by PSI and Indian scientists, including members of the Indian Institute of Technology Kanpur.
New Delhi is one of the most polluted citiesExternal link in the world in terms of air quality. The fine particle content in winter can exceed 500 micrograms per cubic metre, compared with 70 in Beijing and 10 in Zurich, according to PSI.
Popular Stories
More
Workplace Switzerland
Meet the foreigners who make up a quarter of the Swiss population
What can be done to protect biodiversity in your country?
Swiss voters are set to decide on a people’s initiative calling for better protection of ecosystems in the country. Have your say on the September 22 vote.
Green Liberal party members criticise handling of Ameti affair
This content was published on
Some Green Liberals say the party acted too quickly after Zurich politician Sanija Ameti fired shots at an image of Jesus and Mary.
This content was published on
Switzerland has a new supercomputer named "Alps", officially inaugurated on Saturday at the National Supercomputing Centre in Lugano.
Cold front leads to record-low temperatures in Switzerland
This content was published on
Friday's cold front caused record temperatures and closed mountain passes. The snow line was between 1,200 and 1,500m on Saturday, MeteoSwiss reported.
Collecting of vote signatures to continue in Switzerland as planned
This content was published on
The Swiss government is refraining from taking drastic emergency measures following the revelation of suspected cases of fraud.
Swiss VAT to rise by 0.7 points to finance 13th pension payment
This content was published on
VAT is to be increased by 0.7 percentage points in Switzerland to finance the 13th monthly pension payment. This payment will be introduced in 2026.
Swiss rents expected to keep rising owing to low vacancy rates
This content was published on
Although the decline in vacancies has slowed this year, it is likely to continue next year, according to UBS. As a result, rents are expected to continue to rise.
Swiss government wants to support cantons financially after storms
This content was published on
The Swiss government wants to secure additional financial aid for cantons Graubünden, Ticino, Valais, Vaud and Bern following the severe storms last summer.
Eight years for parents who killed disabled daughter in Switzerland
This content was published on
A couple who killed their severely disabled daughter in Hägglingen, northern Switzerland, have each been sentenced to eight years in prison.
If you want to start a conversation about a topic raised in this article or want to report factual errors, email us at english@swissinfo.ch.
Read more
More
Swiss-led research helps uncover new truths about air pollution
This content was published on
At monitoring stations in Switzerland and Europe, scientists are trying to understand how tiny aerosol particles affect the climate and our health.
This content was published on
In an effort to reduce air pollution and its health hazards, the Geneva authorities have approved a measure to ban the most polluting vehicles.
This content was published on
“The government isn’t doing enough to reduce pollution. There is too much black smoke, too many exhaust fumes,” says Mr Ma, a Beijing pensioner who, along with his granddaughter, is taking advantage of a brief interval of clear sky to get some fresh air into his lungs. “I have lung cancer, I can hardly breathe,”…
You can find an overview of ongoing debates with our journalists here . Please join us!
If you want to start a conversation about a topic raised in this article or want to report factual errors, email us at english@swissinfo.ch.