Air pollution has risen to its second highest levels in five years after fireworks were set off to celebrate Chinese New Year.

Dense smog on Saturday (28 January) shrouded the city despite warnings from officials not to light fireworks. There have been bans on selling pyrotechnics and fewer shops are allowed to sell them this year. Neighbourhood posters requested local residents not to set off fireworks and there were fewer approvals for firework stalls.

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But the efforts did not bring down levels of air pollution, despite reducing firework sales: the state-owned Xinhua news agency reported that sales of fireworks dropped by 4.9% in Beijing.

The World Health Organization measures air quality by the amount of small, particles in it, known as PM2.5. Small particles of this size are easily breathed in and can damage the lungs.

A level of PM2.5 – a measure of fine particulate matter damaging to health – spiked at 647 micrograms per cubic meter on Saturday, according to the national ministry of environmental protection. The Beijing Municipal Environmental Protection Bureau said harmful particulate matter in the air had hit the second-highest level in five years, China News Service reported.

These levels are above the upper limit of 500 on China's air quality index and twice that considered hazardous for humans. The greater region of Beijing, the nearby port city of Tianjin and surrounding Hebei province surpassed peak levels of PM2.5 in 2016, the national Ministry of Environmental Protection said in a statement on its website.

Protective face masks were worn by many people celebrating Chinese New Year, including paramilitary police at Bejing's Lama Temple. Up to 80,000 people were expected at the best-known Tibetan Buddhist temple outside of Tibet, state television stated.

Smog was linked to a third of deaths in China, putting air pollution on a par with smoking, according to findings by Nanjing University's School of the Environment. The researchers said they carried out the research because air pollution was the "most severe and worrisome environmental problem in China", according to the South China Morning Post.

The International Energy Agency published its first report on air pollution in June 2016 and estimated that severe air pollution shortened life expectancy in China by an average 25 months.