The first ever ‘red alert' for poor air quality was issued for Beijing, China, by the city government due to heavy smog, multiple sources report.
This alert began on Tuesday morning and will be in effect until Thursday Reuters said.
"High pressure over the area has provided almost calm winds, allowing pollutants to build up with little to no influx of fresh air," AccuWeather Meteorologist Tony Zartman said.
The Beijing city government ordered all outdoor construction to stop and all schools to remain closed until the smog clears.
"Construction waste, excavation transport vehicles, cement trucks, gravel transport vehicles and other large-scale vehicles are prohibited from driving on roads," authorities added in the notice.
This poor air quality will impact the 22.5 million people who live in and around the city.
China has a four-color warning system for pollution conditions. The four levels include blue, yellow, orange and red. The four-color warning system was created in October 2013 according to Xinhuanet news.
A ‘red alert' is issued when there is expected to be at least three consecutive days of very poor air quality, according to the Associated Press (AP).
Beijing was under an orange alert over the weekend but was upgraded to a red alert for this week.
Those with respiratory problems should refrain from going outside until conditions improve. Those with pets should bring them indoors and prevent them from staying outside for extended periods of time.
Car usage will be limited during the alert. Those needing to travel are asked to use public transportation.
Those with cars are allowed to drive on alternative days, depending on whether the car license plate ends in an odd or even number, the BBC said. Those needing to travel are also allowed to use extra public transportation that will be provided.
The city will add more than 20,000 buses, 8,182 of those clean-energy buses, for public transportation use, Xinhuanet news said.
The alert is expected to be lifted on Thursday as winds along a passing front should displace all of the smog out of the city.
"A cold front moving through the area on Thursday will bring a breeze that will help to usher in a fresh air mass from the north and clear the smog out of the city," Zartman said.
While the removal of smog should bring some relief to the air quality on Thursday, smog levels could increase during Friday and the weekend.
"High pressure will build back over the area Friday into the weekend," Zartman added. "Winds will be very light which may allow smog to redevelop once again.
Air quality in Beijing has averaged in the unhealthy level about 50 percent of the time since 2008, the BBC said.
Air pollution can also cause other diseases, some of which can be fatal, according to the World Health Organization.
Smog levels were poor for most of November due to factories and power companies working harder due to the cold weather that occurred, the AP said. Power plants that run on coal is the main contributor to poor air quality in the city.