5 mg dry weight) are made of mixed cellulose esters of acetates or nitrates containing less than 12.6 nitrogen (Figure 1A). To lessen cross contamination of pump tubing and in line chambers, the aerosol pump was applied strictly for aerosol plus the smoke pump strictly for smoke. Just before each aerosol or smoke trial, pump flow prices were equilibrated to 400 ml/min using an Aalborg GFMFrontier