Authorities in the southwestern province of Sichuan on Friday deployed riot police to clamp down on spontaneous anti-smog protests in the provincial capital, Chengdu.
Its residents, unused to the toxic brown haze that regularly engulfs more northern cities like Beijing, came out in spontaneous protest on Friday, both online and on the streets.
"The smog was very thick yesterday, and we couldn't see anything when we got up in the morning," one protester wrote on the social media service Sina Weibo.
"There are people on Chengdu's Tianfu Square protesting right now, but the riot police have been sent in," the student said. "They have sealed off the whole area, and they aren't letting anyone through."
"They won't let anyone linger in the area," the student wrote. "Some protesters are elderly people protesting against the smog, and also the Pengzhou PX plant."
Another netizen posted: "Come on, Chengdu youth! Let's start to express ourselves!
"We won't put up with this! Take to the streets! We are all guilty of producing a world like this. Come on, kids, let's stay alive!"
Photos of downtown Chengdu showed masks put on a modern sculpture of ordinary working people, while netizens posted photos of themselves with placards calling on the government to do something about the air quality.
"Let me breathe!" read one placard. "I call on the government to take action air and quality!" read another.
Bulk orders of face masks
Meanwhile, a police notice sent to local businesses warned them to be vigilant for any seeking photocopy large numbers of posters complaining about the air quality, or to buy bulk orders of face-masks.
"Apart from taking down their ID card details and a contact phone number, please contact the [local] police station immediately," the notice, signed by "Officer Zhang" at the Jitou police station, said.
The city, which has until now enjoyed relatively clean air to breathe, has been swathed in smog since last week, when around 20,000 passengers were left stranded its airport due to low visibility.
According to the World Air Quality Index, the city's air quality was at 280, considered in the "very unhealthy" range.
A Chengdu resident surnamed Feng said local people aren't used to having to wear face-masks to avoid inhaling pollutants like PM2.5 particles.
"The air pollution is very bad in Chengdu right now," Feng said. "All the traffic cops and the urban management officers are wearing face-masks, and some students are wearing them in school, as well."
"There have been some signature campaigns and protests against the smog," he said. "I didn't go there in person; I saw them online."
A resident surnamed Li said people with chronic health problems have been warned not to go outside.
"This sort of smoggy weather makes breathing very uncomfortable, and a lot of people are wearing masks to go outside now," she said.
Zero visibility in Chengdu
A third Chengdu resident, who asked not to be named, said expressways in the city had been shut down owing to poor visibility.
"On Dec. 6, visibility was basically zero ... you couldn't see a thing," he said. "It has never been this bad before."
China's cabinet, the State Council, on Monday released details of its five-year plan to address widespread pollution of the country's air, soil and water, launching a campaign to reduce PM2.5 concentrations by 18 percent in the worst-polluted cities by 2020.
Vice minister of environmental protection Zhao Yingmin vowed a "stricter-than-ever" approach to tackling pollution, including eight obligatory targets.
But environmental activists say the government needs to target pollution before it is even produced, in order for the plans to work.
Pollution is referred to the country's environmental protection agencies only after it is detected, while local authorities are finding ways to tamper with real-time data channeled back to Beijing, they say.
Experts estimate that some 350,000 to 500,000 people die prematurely per year from air pollution in China alone.
Red smog alerts were issued last week for Linfen city in Shanxi province and Hebei's Shijiazhuang, Baoding, Langfang, Xingtai, and Handan cities in the northern province of Hebei.
Beijing also issued an orange-alert smog warning, effectively ordering schools to cancel outdoor activities and suspending construction projects until last weekend.
Beijing residents woke up to thick smog last weekend, with visibility of just 500 meters in some areas, and pollution readings climbing over the 500 mark, the most hazardous to human health.
Reported by Qiao Long for RFA's Mandarin Service. Translated and written in English by Luisetta Mudie.