Unep atmospheric brown cloud project report: Cities across Asia get dimmer

Around 13 megacities have so far been identified as ABC hotpots. Bangkok, Beijing, Cairo, Dhaka, Karachi, Kolkata, Lagos, Mumbai, New Delhi, Seoul, Shanghai, Shenzhen and Tehran where soot levels are 10 per cent of the total mass of all human-made particles. ABCs can reduce sunlight hitting the Earth's surface in two ways.