Indoor air quality monitoring via it network colorimetric monitoring of formaldehyde in indoor environment using image transmission of mobile phone

A simple and rapid monitoring system of indoor air pollution is proposed by integrating a colorimetric detection method of formaldehyde (HCHO) and a function of image transmission of a mobile phone via IT network. The colorimetric detector employs a solid phase colorimetric reagent made from AHMT, ZnO, KIO₄ and agar, and discolors from white to purple when exposed to a certain amount of HCHO gas. Although the color degree responds to the HCHO concentration levels, visual judgment often involves personal bias that leads to uncertainty. In this feasibility study, variation of the acquired photo images expressed in RGB model was investigated by changing a type of mobile phone and conditions of photography. As a result, the calibration of the measured color degree with a color standard reduced the variation of the results and gave a significant color degree when the images were taken under the consistent condition. Since the light source was one of the significant elements for image analysis, the light condition should be decided for practical applications.