BEIJING - The density of PM2.5, the primary measurement of air pollutants, in 74 major Chinese cities dropped by 7.9 percent in the first half of 2014 compared with the same period last year.

The density of PM10, particles under 10 microns in diameter, was down by 6.5 percent, according to a report on the enforcement of Law on the Prevention and Control of Atmospheric Pollution, which was submitted to the National People's Congress Standing Committee, China's top legislature, for deliberation on Wednesday.

China vows to strengthen air pollution control. Smog-prone Beijing will adopt a special air pollution control plan for next month's APEC meetings, which features temporary closure of factories in the event of a pollution warning.