Each city therefore has its own unique PM fingerprint. In Stockholm, Sweden, the first days of spring are heralded when up to 74 per cent of PM10 comes from road dust as winter studded tyres rip up the road surface exposed by melting snow. In Delhi in 2012, the biggest single source of PM2.5 was transport (17 per cent), followed by power plants (16 per cent), brick kilns (15 per cent), industry (14 per cent), households (12 per cent), waste burning (8 per cent), diesel generators (6 per cent), road dust (6 per cent) and construction (5 per cent).
Each city has a unique PM fingerprint
