India Today | Delhi's air among dirtiest in the world, reveals WHO report India Today Pollution levels have worsened across the world since 2011, when WHO released its much smaller survey, increasing the risk of heart and lung diseases and cancer. The average air pollution in terms of microgrammes of small particulates, known as PM10 ... WHO: Delhi most polluted city Delhi is the most polluted city: World Health Organization World Health Organisation warns Delhi's dirty air is at 'critical' level |