HANOI, Nov. 8 (Xinhua) -- The overall air quality in Vietnam's capital Hanoi reached unhealthy levels on Tuesday, thus putting the general public at risk of adverse respiratory effects.
Air monitoring stations in Hanoi reported the Air Quality Index (AQI) as red (AQI 151-200, "unhealthy"), with some areas reaching purple (AQI 201-300, "very unhealthy") as of Tuesday morning.
The severe air pollution in the city is forecast to linger until this weekend, leaving much of the city clouded in smog, the local newspaper Vietnam News reported.
Air quality usually drops between October and March for between two and 14 days at a time, the newspaper cited Ha Thanh Huong, project manager of PAM Air, a private air quality network in Vietnam.
According to environmental experts, air pollution in Hanoi is related to meteorology. In the past few days, the weather has experienced a temperature inversion, causing pollutants from traffic, construction, industrial production, craft villages and daily life activities to be deposited in the air near the ground, leading to air pollution.