A method and system for personal environmental monitoring using a mobile device are provided herein. The method may include: determining an ultraviolet index, “UVI”, in the vicinity of the mobile device, based on data received from the mobile device; determining a modified UVI, “m-UVI”, based on at least one of further data received from the mobile device and data input by a user of the mobile device; determining a predicted exposure of the user of the mobile device, based on the m-UVI; determining a minimal erythemal dose, “MED”, of the user based on an input skin type of the user; providing an erythema timer based on the m-UVI and the MED; and continually updating the erythema timer based on changing environmental or user conditions, wherein the received data corresponds to at least one of: a current time; a geolocation of the mobile device; and an altitude of the mobile device.