BEIJING, March 6 -- The Lantern Festival, which fell on Thursday, saw Beijing's residents flock to the street to watch and set off fireworks, however, the colorful seasonal displays came with a downside -- dragging the air quality down.

The Beijing Municipal Heavy Air Pollution Emergency Response Office issued a blue alert at 6 p.m. on Thursday, forecasting heavy pollution in the city and advised residents to hold back on firework displays, as the weather was not conducive to dispersing the pollutants.

Peak readings of PM 2.5, or airborne particles smaller than 2.5 microns in diameter that cause smog, reached 224 micrograms per cubic meter of air on average at 10 p.m.. The highest reading was at Xizhimen, Xicheng District, of 638 microgram per cubic meter, according to the environmental protection monitoring department.

The office said air quality would not improve until Saturday evening, when a cold front is expected.

Thursday was the fifteenth day of the first lunar month, when Chinese eat sweet dumplings, play with lantern puzzles, compete in dragon boat races and set off fireworks.

For air quality and safety concerns, Beijing banned fireworks in its urban area, only allowing displays from the eve of Spring Festival to Lantern Festival.