Abstract
We measured an indoor formaldehyde (HCHO) concentration in Sendai-around area using a passive analytical chip combining a porous glass and β-diketone, during the summer and the winter in 2023. The average temperature in 2023 summer was 2 °C higher than that for the past 10 years. The HCHO concentration was calculated both from the absorbance changes at 414 nm of the analytical chip before and after exposure to an indoor air and from exposure time. In the measurements, HCHO concentration and questionnaire results were obtained from 142 and 144 rooms and the obtained HCHO average concentration was 37 ppb and 19 ppb in summer and winter, respectively. Room temperature has a large contribution to HCHO concentration, and the measurement results showed that the concentration increases 1.09 times for a 1 °C increase in temperature. It was also found that opening the windows was the most effective way to reduce HCHO concentration of the indoor air, and in the case of condominium, opening the windows for 30 minutes was estimated to reduce the HCHO concentration by 60%. We also have measured the adsorption ability of the materials, such as a wallpaper, igusa sheet for tatami, and diatomaceous earth, which were used in construction of house. The best adsorption performance was obtained for diatomaceous earth and it was 23.0 ng/g in 1 L of air with 160 ppb of formaldehyde. Although the indoor concentration of HCHO tends to be lower, the summer temperature will be higher than we have never experienced, and the indoor concentration of HCHO assumed to be higher, therefore to check indoor air condition become more important. In that case, the developed analytical chip is expected to function effectively.
