The results of that study indicated that symptoms caused by
exposure to PM10 were as follows: fewer than 259 subjects had
regular cough, fewer than 179 subjects had chronic cough or sputum,
and fewer than 137 subjects had wheeze and shortness of breath.
Therefore, a decline in particle concentration in Switzerland during
the 11-year follow-up period was beneficial to improving respiratory
symptoms among adults. However, in an experiment among
children aged 24 months in New York City from 1998 to 2006, increased
ambient nickel and vanadium levels were significantly
related to wheeze, and increased elemental carbon levels were significantly
related to cough during cold and flu season; however, total
PM2.5 did not show an association with wheeze or cough [15].