Impact of indoor environmental parameters on formaldehyde concentrations in unoccupied research houses.

An environmental parameters study has examined the impact of indoor temperature (T) and relative humidity (RH) levels on formaldehyde (CH/sub 2/O) concentrations inside two unoccupied research houses where the primary CH/sub 2/O emitter is particleboard underlayment. The data were fit to a simple three-term, steady state model describing the T and RH dependence of CH/sub 2/O concentration in a single compartment with a single CH/sub 2/O emitter. The model incorporates an Arrhenius T dependence and a nonlinear RH dependence of the CH/sub 2/O vapor concentration within the solid CH/sub 2/O emitter. The RH dependence is based on Freundlich's theory of the adsorption of water vapor on solid surfaces. The model is used to estimate potential seasonal variation in CH/sub 2/O concentrations under specified experimental conditions inside the research houses. The modeled results indicate six- to ninefold variation between 18/sup 0/C, 20% RH and 32/sup 0/C, 80% RH, simulating potential winter/summer conditions with minimal indoor climate control. In comparison, indoor conditions ranging from 20/sup 0/C, 30% RH to 26/sup 0/C, 60% RH yielded approximate two- to fourfold fluctuations in CH/sub 2/O concentration. The research house data were also used to evaluate the limitations and applicability of more complex five-term models developedmore » from small-scale chamber studies of the environmental dependence of CH/sub 2/O emissions from particleboard underlayment.« less