Fireworks will not light up the night skylines of most Chinese cities as they usually do during Lantern Festival as severe smog shrouded China on Friday.

According to tradition, all remaining fireworks and firecrackers are set off during the Lantern Festival to bid farewell to the Spring Festival season, which falls during the first half of the first month of the Chinese lunar calendar.

Heavy smog has enveloped Beijing since Friday morning with the air quality index (AQI) at stations in urban areas reaching Level 5, or heavily polluted. The city's weather department advised locals not to set off fireworks during Lantern Festival, which is the last legal day for fireworks celebrations.

In Taiyuan, capital city of the northern province of Shanxi, fireworks have been restricted to a few villages and townships far from downtown, while public departments, social organizations and companies are forbidden to set off fireworks.

Some shops choose the auspicious day to open business, which means setting off a string of firecrackers and fireworks in the morning. But this year, a street cleaner in east China's Nanchang City said workload was cut by half due to less firecracker debris and trash.

Jiangxi Province, an important place for firework production, registered a sharp decrease in sales in the domestic market. Shen Haobo, a manager of a Jiangxi fireworks logistics center, estimated a 40-percent drop in sales this year for his company.

Experts warned that fireworks, though not a main cause of smog and haze compared with construction dust and vehicle exhaust, can aggravate air pollution under extremely bad weather conditions.