Elevator Ventilation and SARS-CoV-2-Relevant Particulate Matter Removal in Three Older California Elevators

Table 2

Summary description of experimental tests and associated variables.

Variable	Loss rate experiment	Door status	Measurement
	Background CO2 concentration	Closed	Mean baseline CO2 concentration
	Normal stationary natural ventilation	Closed	Rate of decay of generated CO2 due to natural ventilation of elevator
	Normal particle removal in stationary elevator	Closed	Rate of decay of PM2 due to deposition onto elevator surfaces
	Normal particle removal rate in moving elevator	Variable	Rate of decay of PM2 due to removal mechanisms in a moving elevator
	Intervention stationary: stationary elevator+HEPA air cleaner	Closed	Rate of decay of PM2 due to deposition onto elevator surfaces with HEPA air cleaner
	Intervention moving: moving elevator+HEPA air cleaner	Variable	Rate of decay of PM2 due to incremental removal mechanisms in a moving elevator with HEPA air cleaner
	Intervention stationary: stationary elevator+door open	Open	Rate of decay of PM2 due to deposition onto elevator surfaces and door propped open for five minutes

is assumed to be present in all observed results.