A citizen wears a dust mask to protect from smoggy weather in Beijing. [File photo/China Daily]

Public criticism of the heavy air pollution behind recent hazy skies has not stopped authorities in Beijing and other smog-shrouded cities from updating their air quality readings.

Data from Beijing's environmental authorities show that readings for PM2.5, airborne particles measuring less than 2.5 microns in diameter, reached more than 300 micrograms per cubic meter of air at some monitoring stations at 5 p.m. Tuesday.

On Saturday evening, the city's environmental authorities said PM2.5 readings indicated "extreme, severe pollution," as PM2.5 readings reached as high as 900 at certain monitoring stations.

Other cities in the "pollution belt," including Tianjin and Shijiazhuang, also continued to release real-time air quality monitoring data.

Upon seeing the "horrible" data, many citizens rushed to buy protective masks or simply stayed home.

"The government is not concealing the data now. We can at least know the true conditions we are in," said Wang Tianwei, a 25-year-old from Beijing.

Wang said he was not too bothered by recent brown skies, as he can remember many other examples of extreme weather conditions.

Zhu Tong, an environmental sciences and engineering professor with Peking University, cited research showing that the air quality in Beijing has not worsened in recent years, but has remained nearly static or improved.

China previously used PM10, airborne particles measuring 10 microns or less in diameter, as its official standard for measuring air quality, but this can not assess smaller pollutants in the air, Zhu said.

"The measuring standards have been lifted, which directly contributed to higher pollution readings," he added.