The average density of PM2.5 particles in Beijing has dropped to a record low for five consecutive days, following measures to ensure clearer skies ahead of a major military parade in September.

Analysts said more measures are needed to sustain the city's air quality.

Zhang Dawei, director of the Beijing Municipal Environmental Monitoring Center, said that Beijing's average PM2.5 density, airborne particles measuring less than 2.5 microns, was 19.5 micrograms per cubic meter from August 20 to 24, the lowest level since monitoring began in 2012, the Xinhua News Agency reported Tuesday.

The average density of PM10 particles, composed of sulfur dioxide and nitrogen dioxide, also decreased sharply compared with the same period last year, according to Zhang.

Beijing has taken measures since August 20 to ensure clear skies for the military parade on September 3 to commemorate the 70th anniversary of the victory in the Chinese People's War of Resistance against Japanese Aggression and the end of World War II.

Beijing residents posted photos of clear skies on their social media accounts, calling it "parade blue," and said they hope it stays that way.

"No fumes from factories, lower automobile exhaust emissions, only white clouds and blue skies. How long will the 'parade blue' last?" a netizen, "junbibi," wrote on his Sina Weibo.

"It is not easy to keep the 'parade blue' with the current temporary measures considering the expense and inconvenience to residents' lives," Zhang Yuanxun, a professor of resources and environment at the Chinese Academy of Sciences, told the Global Times.

The number of vehicles on the road is managed based on the license plate odd-even rule from August 20 to September 3. Vehicles, especially trucks from out-of-town and those with excessive emissions, are banned from entering Beijing.

Zhang Dawei said the density of nitric oxide, a compound from vehicle exhaust emissions, was cut by over half during the morning rush hours.

A total number of 1,927 industrial structures, including petrochemical and cement plants, have been ordered to suspend their operations and 453 construction sites to suspend work to control the spread of dust, The Beijing News reported on Tuesday.

 "Authorities can use this opportunity to identify the sources of pollution and come up with plans to reduce industrial and vehicle emissions," said Zhang Yuanxun.

Ma Jun, director of the Institute of Public and Environmental Affairs, told the Global Times that "regional cooperation is needed to deal with pollution. A uniform standard could help manage industrial emissions and improve air quality in the region."

Authorities need to enforcing stricter rules on reducing emissions and accelerating industrial upgrades, Ma said.