4 . Environmental group examines air quality monitoring in 113 Chinese cities . The study found that the average concentration of PM2.5 particles was more than double what is considered safe for human health and well below WHO guidelines set by a World Health Organization panel. But 29 Chinese cities publish no data about air pollution .
Environmental group examines air quality monitoring in 113 Chinese cities . The study found that the average concentration of PM2.5 particles was more than double what is considered safe for human health and well below WHO guidelines set by a World Health Organization panel. But 29 Chinese cities publish no data about air pollution .