The fall of visibility is, however, not due to fog. “For fog you need high amount of humidity. What we are seeing in Delhi right now is haze caused due to an inversion that has developed over the city,” explained B P Yadav, Director of the Meteorological Department’s Mausam Vibhag on Lodhi Road.

“It’s a classic phenomenon that occurs in the month of November. The upper layers of the atmosphere get warmer than the lower ones, exactly opposite to the normal condition. As a result, smoke and dust particles are unable to rise, they stay close to the ground, reducing visibility,” he added.

But this atmospheric phenomenon can affect more than just driving. The significant particles that can’t rise in the air during an inversion are not dust particles, they are particles released from industrial smoke stacks and from car emissions. Both of these usually contain carbon monoxide and sulphur oxides, which are toxic when inhaled, and cause various health problems ranging from breathing troubles to cardiovascular conditions. They can also damage lung tissue in extreme cases.

And the bad news doesn’t end here.

According to the Centre for Science and Environment, air pollution levels in the city are already as high as they were during the pre-CNG days. “We will have to take tough measures to control the growing air pollution, and do it fast. Otherwise, Delhi will find itself in the choked and toxic haze of the pre-CNG days, when diesel-driven buses and autos had made it one of the most polluted cities on earth,” said Sunita Nair, Director, CSE.

The CSE analysis, however, acknowledged that various measures — advanced emission norms for vehicles, strengthening the ‘pollution under control’ system and restricting commercial vehicles from entering the city — had been taken to check air pollution.

Put together, the inversion and pollution levels might choke the green lungs the city developed after a slew of measures were taken by the government between 1993 and 2002, which also stop deaths occurring due to the toxic air.

“For the inversion to go, we need a sudden rise in humidity. This usually happens when it rains. Unfortunately, no rains are expected in the Delhi region in the near future,” said Yadav.

Until it rains, Delhi will have to witness a pre-Diwali toxic atmosphere for which crackers can’t be blamed. But needless to say, the air is expected to get a lot more polluted after Diwali.

Nair said: “There is a need for second generation reforms that address new challenges such as the exponential growth of private vehicles and in particular diesel vehicles in the city.”

With such reforms not expected very soon, Delhiites should brace itself for a toxic winter ahead.