Stock image READING is among the most polluted areas in the UK, with residents exposed to levels above the safe limit recommended by the World Health Organisation (WHO), figures reveal. Health campaigners say toxic air quality in the UK is a national emergency and the government must impose stricter limits on fine particles in the air (PM2.5), which come mainly from the burning of oil, gas and diesel. The calls have been heightened after a coroner, while ruling that air pollution was a cause of the death of a nine-year-old girl in London, said there was no safe level of PM2.5, adding WHO guidelines should be seen as minimum requirements .