We will develop a new product to monitor the accumulated exposure to toxic gases, based on colorimetric dosimetry; this is a color change that develops following the persistent exposure to a target gas. The product will consist of inexpensive disposable tags -a carton/plastic card with the colorimetric reagent printed on it- that could be easily wore -e.g. as an employee ID badge during the working time-. After their use, the tags can be immediately and bulk read by a camera (e.g. smartphone).