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Pollution soared to five times the safe level as Shanghai residents welcomed the God of Fortune with a citywide fireworks display, officials said yesterday.

Starting on Thursday evening and continuing into yesterday, fireworks could be seen all over the city to mark the arrival of the fifth day of the Lunar New Year.

According to Chinese tradition, the God of Fortune, or caishen, comes down from heaven on this day. Fireworks and firecrackers are set off to welcome caishen who is believed to bring good fortune.

However, Shanghai Environmental Monitoring Center reported that overall air quality plunged to the "medium polluted" level during celebrations.

Fireworks and firecrackers release polluting chemicals and metal particulates into the air.

Air quality was worst between midnight and 1am - the traditional peak for celebrations - with the center reporting 362 micrograms of PM2.5 particulates in each cubic meter of air.

This is almost five times the 75 micrograms per cubic meter set by the government as safety standard, part of a package of new air monitoring regulations that will soon take effect.

"When peak numbers of fireworks and firecrackers were being set off between midnight and 1am, the index soared," said Duan Yusen, chief forecaster at the center.

Air quality recovered yesterday as the wind dispersed pollutants and air quality remained at "good," said the environmental watchdog.

But these alarming statistics have led local residents to call for a greener way to celebrate the Spring Festival.

Web users on Weibo microblogging platform called on people to sign up to a campaign promising to minimize the use of fireworks and firecrackers to celebrate the Lunar New Year.

"I didn't light any firecrackers today and I hope the God of Fortune will favor me for celebrating in such an environment-friendly way," said a young man with the user name "Potato" on Weibo yesterday.

This year, Shanghai will release a daily PM2.5 index, following calls from the public urging the government to replace the less accurate PM10 monitoring gauge, which measures larger particles.

Meanwhile, welcoming the God of Fortune resulted in accidents with fireworks that left two people with severe facial injuries.

A 23-year man, surnamed Yu, was thrown to the ground by a blast while setting off a firework in northeast Yangpu District at about 11:30pm on Thursday.

Left unconscious, he lost most of his teeth, suffered damage to his chin and almost choked on his own blood. Yu was reported to be in a serious condition at hospital yesterday.

And a 35-year woman, surnamed Fan, was injured by firework in Baoshan District.

Witnesses said she was injured when a firework exploded as she was checking whether it was lit.

The blast left Fan with an injured jaw, two broken teeth, singed hair and burns to her forehead.

Earlier on Thursday, 14 new cars were destroyed in a fire at a car showroom in Minhang District.

The cause of the blaze is under investigation, said officials.