The Vietnam Environment Administration (VEA), which monitors the environment, said that in this period, in terms of suspended particulates, 42 out of a total of 93 values exceeded acceptable levels for an average of one hour a day in 28 cities and provinces.
The pollution was most clearly observed at traffic axes and industrial zones, with the worst values recorded at the Pho Noi A and Nhu Quynh industrial parks in Hung Yen Province, and Dai An IP in Hai Duong Province, where the average suspended particles were half again higher than Vietnam's acceptable levels at 452.3 µg/m3.
Residential areas too were polluted with the rate of suspended particles at three out of nine monitoring stations - Pho Noi-Hung Yen area in Hung Yen Province, near Ha Dong beer company in Hanoi and near the martyrs cemetery in Bac Ninh Province - exceeding safe levels.
As for water, 185 monitoring stations in five rivers in the north showed that the water quality index (WQI) at 70 percent of stations was very good (91-100) or good (76-90), 18 percent was average (51-75) and 12 percent was bad and very bad.
Low WQI values were found in the Nhue River and its branches in Hanoi and the Cau River and its branches in Bac Ninh Province.
They are polluted by untreated domestic wastewater in Hanoi and Thai Nguyen Province and wastewater discharged from craft villages in Bac Ninh.
The worst pollution was recorded in the Ngu Huyen Khe branch of the Cau River: a WQI value of just 12. The biochemical oxygen demand (BOD5), the most widely used parameter applied to wastewater and a measure of the dissolved oxygen required by microorganisms to oxidize or decompose the organic matter in wastewater, in this section was 133 mg per liter, nine times the standard value.
In the Bong Toi stream, a section of the Nhue River in Thai Nguyen Province, the ammonia nitrogen (NH4-N) level was 31 times the standard level of 0.9 mg per liter.
As assigned by the environment ministry, the VEA collected the data for the monitoring in January and February, and had yet to announce the figures for March.