Nearly half of Shenzhen's main roads produced more noise pollution than allowed last year, the environmental protection bureau announced Saturday in its annual report.

Main roads recorded an average of 69.6 decibels of noise, up 0.2 decibels from the previous year's figure. A total of 44.6 percent of the roads produced excessive noise, due to a surge in the number of vehicles, the Daily Sunshine quoted the report as saying yesterday.

On the average, the city recorded 56.5 decibels of noise last year, up 0.3 decibels from the previous year. About 85 percent of the city's total area meets noise control standards.

The authorities have pledged to renovate road surfaces, set up barriers along roads and tighten controls on vehicles to reduce the noise.

The city recorded 359 days of good air quality last year, and 98 percent of drinking water sources met quality standards.

However, more days with acid rain were recorded - four out of five days all year round.

Major air pollutants last year were sulfur dioxide and nitrogen dioxide, both increasing on the previous year. The density of particles in the air reached 0.064mg per cubic meter, the same as the previous year.

Though major water sources were described as good quality last year, serious pollution was found in the lower reaches of Shenzhen River, Buji River, Xinzhou River and many other rivers.

While the west coast was seriously polluted, the city's eastern coast was fairly clean.

The authorities also predicted a quick improvement in the water quality of the west coast next year, after completion of a sewage plant in Nanshan District.

Editor: Yan