Metals, particularly nickel and vanadium, and sulphate particles -- components of fine particulate air pollution (PM2.5) -- can worsen asthma and lead to hospitalisation, according to a new study.

The study, published in the American Journal of Respiratory and Critical Care Medicine, showed that for each decile increase in the pollutant mixture, asthma hospitalisations increased 10.6 per cent among children and 8 per cent among adults ages 19 to 64.

Nickel, vanadium, sulfate, nitrate, bromine, and ammonium contributed the most weight to this association.