The Chinese capital's fine-particulate pollutant intensity is expected to drop to the internationally recognized safe level in 16 years, environmental authorities said.

Pan Tao, head of the Beijing Municipal Research Institute of Environmental Protection, said the concentration of PM2.5 - particulate matter with a diameter of 2.5 micrograms or less per cubic meter - is likely to be reduced regularly to no more than 35 micrograms per cubic meter by 2030.

"Improving air quality in the city is not going to be an easy task," Pan said on Tuesday during the 2014 Beijing International Academic Symposium on Urban Environment.