ABSTRACT
Objective To observe the effect of relative humidity on indoor concentrations of formaldehyde and ammonia. Methods 12 currently decorated rooms were randomly divided into 3 groups, 4 rooms involved in each, in which the average relative humidity of rooms were 55%,65% and 75% respectively. The concentrations of formaldehyde, ammonia were monitored every two days for 9 consecutive days according to GB/T18204.26 -2000 and GB/T18204.25-2000. Results The concentrations of formaldehyde and ammonia decreased gradually with the prolongation of the experimental period. The concentrations of formaldehyde in the rooms of 55%,65% and 75% relative humidity groups decreased significantly after the 5th, 3rd, 3rd day of the experiment compared with those in the same group at the 1st day of the experiment respectively(P