BEIJING, Jan. 10 (Xinhua) -- Beijing saw major air pollutants plummet in the the last quarter of 2017 thanks to a string of measures to improve air quality, the environmental protection ministry said Wednesday.

The density of PM2.5 in Beijing dropped by 53.8 percent in the October-December period year on year while that for December plummeted by nearly 70 percent, according to a statement on the ministry's website.

An air pollution plan issued by the State Council in September 2013 ordered Beijing to reduce its PM2.5 density from 90 micrograms per cubic meter in 2013 to around 60 micrograms per cubic meter by the end of 2017.

The average density of PM2.5 in Beijing was 58 micrograms per cubic meter last year thanks to effective pollution controls including demolition of coal-fired boilers and the phasing out of vehicles with high emissions.

The statement showed that 28 monitored cities saw an average drop in PM2.5 density of 34.3 percent in Q4 last year, with Shijiazhuang, capital city of Hebei Province, achieving the biggest progress by reducing PM2.5 density by 54.8 percent.

Clear air is expected in early January in north China, and the Beijing-Tianjin-Hebei region in particular, thanks to a strong cold front, while these areas might see worsening air quality in late January and early February due to unfavorable weather conditions.