This test strip is for the determination of ozone in air. Ozone is a colourless toxic gas. It is irritating to eyes and mucous membranes and can cause respiratory complaints. An ozone content of 180 micrograms/ m3 is considered as critical value above which sensitive persons should avoid stronger physical exertion. The ozone values published by public media like press, radio or TV represent the ozone concentrations in the vicinity of the measuring stations. However, actual ozone values in other locations can considerably deviate from these published values due to meteorological and chemical influences such as wind, solar radiation, exhaust gases from vehicles etc. For this reason a local measurement of ozone concentrations is recommended. gradation of scale: less than 90, 90 -150, 150 - 210, greater than 210 micrograms/m 3 ozoneMethod of application: Place a test stick in the open air, protected from wind. If necessary, fix the test stick with a piece of adhesive tape. After 10 minutes compare the test field with the colour scale on the container. Under standard conditions (101300 Pa, 20°C): 90 micrograms per meter cube ---> 0,0451 ppm, 150 micrograms per meter cube---> 0,0752 ppm, 210 micrograms per meter cube ---> 0,105 ppm Interferences: Other oxidizing reagents (e.g. chlorine) cause a similar colour change and simulate too high an ozone value. The measuring ranges are valid for a relative atmospheric humidity of 30 to 60%. Humidity values below 30% can cause lower ozone values, humidity above 60% higher values than actually present.