Police in the southwestern Chinese city of Chengdu stepped up security amid mounting public complaints about smog, after briefly taking away eight mask-wearing protesters for questioning on Sunday night. The protest came as pollution problems worsen in China, forcing the government to be extremely sensitive about social unrest over environmental issues. The demonstrators were artists staging a brief sit-in after a mass protest over the pollution – planned for the weekend – was pre-empted by police. Police had closed the square where it was to be held. Planned protest against smog in southwest China shut down before it begins Photographs and posts on social media by the artists’ friends and relatives showed that they were taken away from a busy shopping area in Chengdu, Sichuan province, where they had been sitting in a row for about 10 minutes with their masks on. They were taken to a nearby police station and released a few hours later, according to the posts. The city’s Tianfu Square, where the mass weekend protest had been planned, was still closed on Monday, with parked police cars and officers preventing people from entering. 今晚的春熙路。 #成都反毒霾保命运动 pic.twitter.com/kuV4EVFSS4 — 佩利 (@paleylin) December 11, 2016 <!--//--><![CDATA[// ><!--\n\n\n//--><!]]> The capital of Sichuan province has experienced severe smog during the past week, but city authorities have issued only a yellow alert – the lowest in a three-tier system. This led to public suspicions that the authorities were trying to cover up the seriousness of the problem. The smog had cleared up on Monday and a result of growing winds. Chengdu city government said yesterday that it would “wage a war” to tackle the problem of pollution. It also launched a media campaign publicising official pollution-control efforts. Unable to walk the walk, Chengdu residents talk the talk University students received notices on their mobile phones banning them from wearing masks or sharing smog-related articles on social media. Many locals blame the Pengzhou petrochemical project, 40km from the centre of Chengdu, for the city’s worsening air quality over the past few years. The project triggered widespread criticism during its preparation stage and fierce local protests when construction of the plant began in 2013. Police also detained one man for sharing photos that purportedly showed a huge crowd protesting about the smog, but it was actually taken in 2012, the Global Times reported. There have been protests about industrial projects in mainland cities, but mass demonstrations about smog are rare, even in the hard-hit Beijing-Tianjin-Hebei area.