Winter season temperature drops and sulfur dioxide levels affect on exacerbation of refractory asthma in South Korea: a time-trend controlled case-crossover study using soonchunhyang asthma cohort data.

Winter season temperature drops and sulfur dioxide levels affect on exacerbation of refractory asthma in South Korea: a time-trend controlled case-crossover study using soonchunhyang asthma cohort data.