Kathmandu Valley reached the highest on Friday, the Department of Environment reported.
Information officer at the department Shankar Prasad Poudel said that a significant increase in air pollution due to the dry atmospheric environment.
Likewise, the department has urged everyone to stay alert and opt for all the health safety standards as the air pollution level across the nation is rising daily.
The air pollution in Bhainsepati, Kritipur, Bhaktapur, Sauraha, and Simara among others has reached a hazardous level, said the department.
The air pollution in the Bhainsepati area of Kathmandu had spiked to 230 micrograms per metre cube at 9:00 PM on Thursday and at 3:00 PM on Friday.
The pollution level has also increased in Nepalgunj, Dang, Janakpur, Jumla, and Rara area. The air services have been halted on Friday due to the fog created by the pollution.