The city's environmental authority started publishing daily readings of ozone levels in the air over the weekend, in line with China's new edition of air quality guidelines.
Concentration of ozone, an odorous, pale blue gas, in the ambient air was not public information until the Ministry of Environmental Protection in February sanctioned the new national guidelines of air quality assessment.
The eight-hour average from 9 pm Friday to 8 pm Saturday was 121 micrograms of ozone per cubic meter, according to Beijing Municipal Environmental Monitoring Center. The ministry-approved standard has set the cap at 160 micrograms for urban areas.
Hourly updates on the center's website yesterday show the ozone concentration peaked at 159 micrograms per cubic meter at 4 pm - almost intolerable by the national standard.
Pollutants such as nitric oxides turn into this smelly gas under exposure to the sun. While blocking ultraviolet radiation in the upper atmosphere, too much ozone closer to the ground can affect people with asthma or chronic bronchitis, according to the center.
"Making this information publicly available helps the people better understand the air of their city as well as engage in activities that will lead to betterment," said a center statement on Friday.
Engaging a public with little knowledge of the health risks of ozone is not an easy mission.
"Doesn't it come out of refrigerators?" said Yu Xue, a public relations professional, when approached by the Global Times yesterday.
"I know there is an ozone layer up there," said Liu Cheng, a 26-year-old tennis coach.
Attention drawn to air pollution in the city helped form public policies to upscale standards and improve transparency. However, public involvement in Beijing's air problem has not seemed to go far beyond social media sites.
Liu, who teaches tennis on outdoor courts, said his body is not that sensitive.
"I care more about the weather than pollution because if it rains, I can't work," he said.