The emission factors of the 14 most abundant VOCs on sequential cold weather sampling dates (January 17 and March 12, 2003) are compared in Table 4. Indoor and outdoor temperatures and percent RHs were approximately equivalent between these dates (Table 1). However, the January air change rate was h-1 versus h-1 in March, likely due to the difference in wind conditions. Within both the aldehyde and the terpene hydrocarbon chemical classes, the ratio of the emission factor at the lower air change rate to the emission factor at the higher air change rate was near.