BEIJING, Nov. 25 (Xinhua) -- Beijing's air quality continued to improve this year, with major air pollutant concentrations falling year on year, according to the latest index readings released by the Beijing Municipal Bureau of Ecology and Environment.

The data suggested that the average concentration of PM2.5 in October was 40 micrograms per cubic meter, and the cumulative concentration from January to October was 41 micrograms per cubic meter.

A total of 190 smog-free days have been observed in the first 10 months, accounting for 62.5 percent of the total. Three days of heavy air pollution were recorded, a decrease of six days compared with the same period last year.

From January to October, the city outdated 38,500 diesel trucks and made road inspections over 2.4 million heavy diesel vehicles to check emissions.

Beijing has built more than 2,600 online video monitoring systems for observing dust at construction sites since the start of the year and filed 24,000 cases suspected of violation of no-construction-dust requirements, up 37.3 percent over the same period last year, according to the bureau.