Image copyright AP Image caption Winter smogs are not uncommon in Delhi, but this year has been extreme

For the past week, I have been driving to work through a "pea-souper" - thick fog which has hung menacingly over Delhi and its neighbourhood.

The city has looked like a smoggy dystopia. Residents are mourning the death of the sun. Although the sun made a welcome appearance on Friday, some media reports say the smog is far from defeated and may return during the weekend.

My eyes hurt when I step out, and I spent days nursing a nagging headache. At work, many of my colleagues are wheezing, sniffing and coughing. The papers are full of stories of clinics overrun by patients suffering from respiratory ailments.

Winter smogs are not uncommon in Delhi, but this year has been rather extreme, sending air pollution levels way above permissible limits. The government has blamed farmers who burn straw in neighbouring states.

Independent environment groups insist that rising pollution is to blame.

Researchers belonging to the watchdog Centre for Science and Environment (CSE) say Delhi's air quality has deteriorated sharply - particulate matter in the air has risen by 47% between 2000 and 2011, while nitrogen dioxide levels has leapt by 57%.

Delhi, they say, is a gas chamber: its air contains a lethal cocktail of poisonous gases like nitrogen dioxide, carbon monoxide, ozone, and benzene. Farm fires have merely exacerbated what is an already bad situation.

The government appears to be rather blase about it all, blaming the weather (slow wind speeds, low temperatures and high humidity) and curiously, even hinting at conspiracy by neighbouring states ("It is as if it is deliberately being done to choke Delhi," Chief Minister Sheila Dikshit told a newspaper).

CSE Executive Director Anumita Roychowdhury, in charge of its air pollution and transportation programme, warns that government's response could have disastrous consequences. "Unfortunately, despite the scary hard facts about the elevated cocktail of pollution and health risks, the problem is being dismissed as a mere weather phenomenon," she said.

"In other parts of the world, governments issue warnings and take pollution emergency measures during such severe pollution episodes to protect public health. But we are doing nothing."

She is right. So what has gone so awfully wrong with Delhi's air, a decade after the city earned international plaudits for introducing green fuel and bringing down pollution levels?

Researchers believe that the unfettered growth in the number of vehicles, especially ones driven on diesel, is a key reason.

Delhi alone adds over 1,000 new vehicles every day, half of them diesel-fuelled. The capital has over 6.5 million vehicles, which is more than the total number of vehicles in the cities of Mumbai, Chennai (Madras) and Calcutta.

A thriving suburbia, including areas like Gurgaon, Noida and Faridabad, has meant that over a million vehicles - 70% of them cars - enter and exit Delhi every day. The new vehicles are better, the fuel is cleaner, but their sheer numbers do not do any good to the city's air.

It is not rocket science to conclude that Delhi needs to ramp up its public transport and cut down on private pollution-carrying vehicles.

To be fair, the city has come a long way in improving public transport: the quality of its passenger bus fleet is among the best in India, and an impressive metro railway now links most parts of the city.

But environmental groups like CSE say this is simply not enough.

"Delhi is taking too long to scale up its public transport," says Ms Roychowdhury.

Some 6,000 passenger buses run in the city - but the government itself admits it needs nearly three times that number to cater for peak passenger traffic. The city is bereft of pavements and footpaths, betraying a skewed planning ideology which favours cars over cycles and pedestrians.

Environmentalists also recommend higher parking charges for cars and a crackdown on unauthorised parking to force more car owners to use public transport - parking spaces, by one estimate, gobble up to 10% of Delhi's land, and daily additions of new cars creates demand for parking space that is bigger than 300 football fields every year.

Although cars are the mode of transport for only 14% of travel trips in the city, parking fills up disproportionately large spaces.

Environmentalists also suggest a hike in diesel prices, an upgrade emission standards, the introduction of buses for commuting to and from the suburbs and the imposition of congestion charges. But the authorities don't seem to be listening.