A system and method is provided for detection at least one of nitrite (NO2), nitric oxide (NO), nitrogen dioxide (NO2), and other nitrogen oxides (NOx) on a substrate, such as skin. According to one aspect, a diagnostic device for measuring a concentration of at least one of nitrite (NO2), nitrogen dioxide (NO2), nitric oxide (NO), and other nitrogen oxides (NOx) on a substrate comprises a patch comprising at least one chemical compound capable of reacting with the at least one of nitrite, nitrogen dioxide, nitric oxide, and other nitrogen oxides to provide an indicator.