Figure 2.

E-Cigarette setup. (a) The relay timer switches the e-cigarette on and opens the solenoid valve. (b) The e-cigarette’s pushbutton switch has been shorted enabling it to be turned on when the relay switch is closed. (c) The e-cigarette aerosol is pulled into the impinger that is filled with a spin trap to capture free radicals. (d) The solenoid valve opens, which pulls a vacuum when the relay switch is closed allowing the aerosol to be pulled through the impinger. (e) The flow meter is adjusted to ensure that the volume pulled for each puff is consistent.