BEIJING, April 15 (Xinhua) -- Air quality in the Beijing-Tianjin-Hebei region worsened in March compared with the same period last year, according to the Ministry of Ecology and Environment.

The ratio of average days with good air quality in March for the 13 cities in the region stood at 50.5 percent, down by 15.8 percentage points year on year.

The density of major pollutants like PM 2.5 and PM 10 both grew more than 20 percent year-on-year in March.

Beijing saw the ratio of its good air-quality days in March at 46.7 percent, down by 14.6 percentage points year on year.

However, the region saw more good air-quality days in the first three months thanks to better-than-expected air quality in January and February.

Air pollution may continue to haunt most of the northern region in late April due to weakening cold fronts, according to prediction by the ministry and the China Meteorological Administration.