Ozone Generation from a Germicidal Ultraviolet Lamp with Peak Emission at 222 nm

Recent interest in commercial devices containing germicidalultravioletlamps with a peak emission wavelength at 222 nm (GUV222) has focusedon mitigating virus transmission indoors while posing a minimum riskto human tissue. However, 222 nm light can produce ozone (O-3) in air. O-3 is an undesirable component of indoor airbecause of health impacts from acute to chronic exposure and its abilityto degrade indoor air quality through oxidation chemistry. In seven4 h experiments, we measured the production of O-3 froma single filtered GUV222 lamp in a 31.5 m(3) stainless steelchamber. Using an emission model, we determined an O-3 generationrate of 19.4 ppb(v) h(-1) & PLUSMN; 0.3 ppb(v) h(-1) (equivalent to 1.22 mg h(-1) & PLUSMN; 0.02 mg h(-1)). We estimated the fluencerate from the lamp using two methods: (1) chemical actinometry usingtetrachloroethylene (actinometry) and (2) geometric projection ofthe irradiance field from radial and angular distribution measurementsof the GUV222 lamp fluence (irradiance). Using the estimated lampfluence rates of 2.2 & mu;W cm(-2) (actinometry)and 3.2 & mu;W cm(-2) (irradiance), we predictedproduction of O-3 in our chamber within 20% of the averagemeasured mixing ratio. Future studies should evaluate the indoor airquality impacts of GUV222 technologies.