“…Ozone Exposure Chamber and Procedure. Ozone uptake was measured by passing O 3 through a rectangular reaction chamber with two narrowly spaced painted surfaces on the top and bottom (Figure S1a and b), similar to the reactor used in Webb et al 29 Clean air was supplied by a zeroair generator and the RH was controlled by changing the ratio of dry and wet air (produced by running zero-air through a fritted water bubbler). The O 3 was supplied to the reaction chamber using a mercury lamp and monitored downstream by a recently calibrated ozone analyzer (Thermo, Model 49i).…”