The Pearl River Delta region in Guangdong province has seen improving air quality over the past few years, local authorities said on Sunday.

The density of PM2.5, hazardous airborne particles measuring 2.5 microns or less in diameter, fell to 34 milligrams per cubic meter in 2015 from 58 mg in 2007, according to the provincial environmental protection bureau.

The level nears the healthy maximum of 35 mg per cubic meter set by the government.