A photo shows the blue sky in Lushunkou, Dalian, a city of North China's Liaoning province. [Photo provided to chinadaily.com.cn]

Lushunkou held onto the second place for air quality in Dalian city with an air quality index (AQI) of 3.44 in 2018, according to the statistics released by Dalian Municipal Bureau of Ecology and Environment on Feb 13.

The number of blue sky days, with air quality rated as excellent or good, was 85.9 percent of the whole year, up 8.4 percentage points from 2017.

The average annual concentrations of four primary pollutants – PM2.5, PM10, sulfur dioxide (SO2) and nitrogen dioxide (NO2) – have all met the new quality standard.

In Lushunkou in 2018, the average concentration of PM2.5, or airborne pollutant particles with a diameter below 2.5 micrometers, was 27 micrograms per cubic meter, dropping 18 percent from 2017.