The COVID-19 pandemic has reintroduced questions regarding the potential risk of SARS-CoV-2 exposure amongst passengers on an aircraft. Quantifying risk with computational fluid dynamics models or contact tracing methods alone is challenging, as experimental results for inflight biological aerosols is lacking. Using fluorescent aerosol tracers and real time optical sensors, coupled with DNA-tagged tracers for aerosol deposition, we executed ground and inflight testing on Boeing 767 and 777 airframes. Analysis here represents tracer particles released from a simulated infected passenger, in multiple rows and seats, to determine the exposure risk via penetration into breathing zones in that row and numerous rows ahead and behind the index case. We present here conclusions from 118 releases of fluorescent tracer particles, with 40+ Instantaneous Biological Analyzer and Collector sensors placed in passenger breathing zones for real-time measurement of simulated virus particle penetration. Results from both airframes showed a minimum reduction of 99.54% of 1 μm aerosols from the index source to the breathing zone of a typical passenger seated directly next to the source. An average 99.97 to 99.98% reduction was measured for the breathing zones tested in the 767 and 777, respectively. Contamination of surfaces from aerosol sources was minimal, and DNA-tagged 3 μm tracer aerosol collection techniques agreed with fluorescent methodologies.

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The COVID-19 pandemic has reintroduced questions regarding the potential risk of SARS-CoV-2 exposure amongst passengers on an aircraft. Quantifying risk with computational fluid dynamics models or contact tracing methods alone is challenging, as experimental results for inflight biological aerosols is lacking. Using fluorescent aerosol tracers and real time optical sensors, coupled with DNA-tagged tracers for aerosol deposition, we executed ground and inflight testing on Boeing 767 and 777 airframes.Analysis here represents tracer particles released from a simulated infected passenger, in multiple rows and seats, to determine the exposure risk via penetration into breathing zones in that row and numerous rows ahead and behind the index case. We completed over 65 releases of 180,000,000 fluorescent particles from the source, with 40+ Instantaneous Biological Analyzer and Collector sensors placed in passenger breathing zones for real-time measurement of simulated virus particle penetration.Results from both airframes showed a minimum reduction of 99.54% of 1 µm aerosols from the index source to the breathing zone of a typical passenger seated directly next to the source. An average 99.97 to 99.98% reduction was measured for the breathing zones tested in the 767 and 777, respectively. Contamination of surfaces from aerosol sources was minimal, and DNA-tagged 3 µm tracer aerosol collection techniques agreed with fluorescent methodologies.

An advanced rotating aerosol chamber was developed to study the changes of fluorescence spectral profile and intensity, the viability and the quantitative polymerase chain reaction (qPCR) signal of Escherichia coli aerosol particles as they are exposed to simulated atmospheric conditions over time. These conditions included relative humidity (RH) below 30% or $75%, ozone $100 ppb, volatile organic compounds (VOCs) a-pinene ($5 ppb) or toluene ($45 ppb), and simulated solar (SS) irradiation. Individual experiments examined the effects of these conditions applied individually and in combination. Experimental results demonstrate that the 263 nm laser excited UV fluorescence band (280-400 nm) showed the greatest rate of decrease, and the visible band (400-580 nm) generally had a smaller change rate which followed the change in the UV band. The 351 nm excited visible band (380-650 nm) had the smallest decay rates, and sometimes increased, when exposed to ozone, high RH, and VOCs. Generally, the viability, qPCR signal intensity, and the fluorescence intensity decayed faster when more variables were applied in combination. Simulated solar irradiation was the most dominant factor in the aging process, followed by the combination of high RH and ozone. Interestingly, the decay of fluorescence and qPCR signal do not appear to correlate directly with loss in viability. Therefore, additional studies are expected to further understand the mechanisms by which atmospheric chemical processes impact viability, qPCR signal intensity, and the fluorescence of biological aerosols.