Field survey of indoor air quality in detached houses in Niigata Prefecture.

In this study, measurements of indoor air quality and ventilation rate of detached wooden houses in Niigata Prefecture are carried out. The air quality (the concentration of formaldehyde (HCHO) and volatile organic compounds (VOCs), the air-tightness of the houses and the life style of the occupants were investigated. The temperature and humidity were logged for 1 week at 10-min intervals using stand-alone data loggers. The measuring points were at 110 and 5 cm above the floor and 10 cm below the ceiling. A 2,4-dinitrophenylhydrazine-coated silica (DNPH) cartridge (Waters Sep-Pak XpoSure) was used to measure the concentration of HCHO and a passive air sampler (3M Organic Vapor Monitor) was used to measure the concentration of VOCs in the living room for 1 week. High-performance liquid chromatography (HPLC) and gas chromatography with mass spectrometry (GC/MS) were used to analyze the average weekly concentration of VOCs. The weekly averaged ventilation rate of the house was measured by perfluorocarbon tracer gas technique (PFT). The main results can be summarized as follows. 1. A total of 38.2% of the occupants felt that the indoor air quality was bad when cooking or smoking in the house took place. 2. The HCHO concentration in the houses is inversely proportional to the air leakage from the house, i.e. it was high for airtight houses. 3. The HCHO concentration in older houses is lower than in new houses of similar air-tightness. 4. When building age increases, HCHO concentration in indoor air decreases. 5. Generally the concentration of benzene, toluene, p-dichlorobenzene, o-, m-, p-xylene is high, especially in a newly constructed house.