What Ach is Equivalent to a Passenger Airplane Inflight for Protection from Sars-Cov-2 and Other Aerosol Contaminants?

46 Pages Posted: 13 Oct 2022

Abstract

Multiple authors observed superspreading aboard airplanes with high passenger density was less frequent than expected. This is possibly due to rapid air filtration on airplanes inflight reported by CDC as 20-30 air changes per hour (ACH). Filters may degrade over time with particle loading, but testing ACH typically involves generating aerosol contaminants (e.g. salt water, smoke, tracers) which may be unsafe or disallowed e.g. in occupied rooms or passenger aircraft. Herein we report the first verification, to our knowledge in the open literature, of ACH aboard a commercial airliner while in flight by using a novel test procedure at the most penetrating particle size (MPPS) of 0.3 μm. Procedure uses handheld, 7-channel optical particle counter (HOPC) to track decay of ambient aerosols at MPPS, validated in a room and house. ACH of 0.6 was measured for surface deposition in an unventilated room, and 3 to 17 ACH with low-noise HEPA purifiers at high speed and Do-It-Yourself (DIY) purifiers at low speed (for reduced noise generation) consistent with their CADR based on volume of room and house. Aboard an Airbus A319, HOPC recorded (1) a burst of ambient aerosols when starting from rest on runway suggesting pollution from thrusting engines enters cabin (2) 12 ACH at MPPS after liftoff (3) transient aerosol fluctuations. Air filtration may not stop spread of SARS-Cov-2 at near-field (e.g. talking close by), but can potentially emulate far-field equivalent of N95 with 95% reduction of MPPS particles (20x) in a well-mixed room. Using 0.6 ACH baseline for unventilated rooms, at least 12 ACH at MPPS is required for far-field protection equivalent to N95 (95%). These results offer independent, experimentally-derived interpretations of 12 ACH recommended for airborne infection isolation rooms by CDC and WHO.

Keywords: Air changes per hour, ACH, SARS-Cov-2, Airplane, HEPA, DIY

Suggested Citation

Srikrishna, Devabhaktuni, What Ach is Equivalent to a Passenger Airplane Inflight for Protection from Sars-Cov-2 and Other Aerosol Contaminants?. Available at SSRN: https://ssrn.com/abstract=4246823 or http://dx.doi.org/10.2139/ssrn.4246823

Devabhaktuni Srikrishna (Contact Author)

affiliation not provided to SSRN ( email )

No Address Available

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