The PM2.5 levels in the city is now four times higher than the permissible limit of 60u/mg.

The Millennium City on Thursday had an air quality index (AQI) of 177, marked as unhealthy.

"Ideally, there should not have been such a steep increase in the PM 2.5 (fine particulate matter which is an air pollutant) levels overnight. We will have to check and figure out the cause for the same," a Haryana State Pollution Control Board(HSPCB) official told TOI, referring to the recorded PM 2.5 levels on Wednesday (80u/mg).

The official also pointed out that the department is regularly monitoring air quality in the city and it will also inspect the construction sites to check if the pollution norms are being violated.

Meanwhile, experts are of the view that the government will have to take more stringent measures and merely a ban on construction activities will not improve the air quality.

"The pollution levels are only bound to come down in the coming days. In the long term, more trees need to be planted; roads will have to be cleaned. With a sizeable pollution being caused due to the dust particles, authorities must take the task of cleaning seriously," said environmentalist Vivek Kamboj.

Kamboj added that the new sweeping machines procured by the Municipal Corporation of Gurgaon (MCG) are also not being put to proper use.

It's pertinent to mention that the air quality levels had hit the severe category levels (800 u/mg) in the city post Diwali due to several reasons including burning of crackers and stubble burning in the neighboring states, apart from low wind speed.However, after meteorological changes and an increase in the wind speed, the pollution levels had normalised. TOI had earlier reported that PM 2.5 levels, which were harmful to people's health, were likely to come down with a drop in temperature. The NCR states have been facing wrath for burning stubble, which leads to air pollution.