Smartphone app for residential testing of formaldehyde (SmART-Form)

Abstract Chemical contamination is ubiquitous in the indoor environment, but measurement options are often limited outside of research studies. This is especially true for formaldehyde, a known carcinogen and irritant. The goal of this project was to develop a novel screening tool: a smartphone-based app that can be paired with low-cost colorimetric badges for detection of indoor formaldehyde. The target users include citizen scientists, concerned citizens, public health nurses visiting homes, and researchers with relevant measurement needs. The user interface was designed using a collaborative development model. Badges were exposed to air for 72 h, and the user takes images that are analyzed in the phone. The app itself measures illumination (lightness) to determine color change, which was associated with formaldehyde concentration (R 2  = 0.8811, P 80%) relative humidity. Co-exposure to acetaldehyde or a VOC mixture did not interfere with measurement ( P  = 0.93, P  = 0.07, respectively). Overall, this screening tool can provide inexpensive, accessible information to users about their formaldehyde exposure, which can inform further testing and potential remediation activities.