Air pollution in Pakistan’s second biggest city Lahore soared on Saturday, with an official calling it a record high for the smog-choked mega city.

For days, the city of 14 million people has been enveloped by smog, a mix of fog and pollutants caused by low-grade diesel fumes, smoke from seasonal agricultural burning and winter cooling.

The air quality index, which measures a range of pollutants, spiked at 1,067—well above the level of 300 considered ‘dangerous’—according to data from IQAir.

“We have never reached a level of 1,000,” Jahangir Anwar, a senior environmental protection official in Lahore told AFP.