Potential participants completed a prescreening questionnaire to identify their smoking status, their car Y-27632 clinical trial ownership status, and whether they permitted smoking in their car. The participants were those individuals who identified themselves as being a current smoker (defined as having smoked for at least a year and currently smoking at least once a week), who owned a car, and who permitted smoking in their car. Experimental design Each of the 18 participants participated in each of five experimental conditions. These five conditions varied on dimensions related to differences in ventilation that would be naturally determined by a smoker in a car: Condition 1. Participant smoked a single cigarette in the car with all windows closed and the engine off. Condition 2.

Participant smoked a single cigarette with all windows closed during a 20-min drive. Condition 3. Participant smoked a single cigarette with all windows completely open during a 20-min drive. Condition 4. Participant smoked a single cigarette with all windows closed except the driver’s window, which was rolled down 18 cm, approximately halfway, during a 20-min drive. The participant was instructed to hold the cigarette close to the open window (not sticking it out the window lest the wind extinguish the cigarette) between puffs. Condition 5. Participant smoked a single cigarette with all windows closed but with air conditioning running during a 20-min drive. In Conditions 1�C4, the climate-control fan inside the cars was turned off (set at 0), and the car left in a passive ventilation state (i.e.

, fresh air from outside could naturally pass into the car without the aid of the fan). In Condition 5, the air conditioner and climate-control fan were set to a medium speed (e.g., set at 2 or 3 on a 5-point cooling/speed scale). For all conditions, the air recirculation feature was turned off, allowing a fresh intake of air through the vents. Between each experimental condition, the car doors and/or windows were opened for at least 10 min to clear out the remaining TSP from the previous condition. Readings taken for several minutes prior to the beginning of the next condition indicated that this procedure was sufficient to bring PM2.5 back to baseline levels. We found no significant differences between the precondition and postcondition baseline levels for any of the five experimental conditions (all p values>.

40). The sequence of conditions for each participant varied in their order due to the need to adjust for weather conditions or comfort of the participant (e.g., if it was too cold for participants to complete the open window conditions). Procedures The researcher used the air quality monitoring equipment to measure the level of PM2.5 for 25 Brefeldin_A min in the car during each condition and for 5 min outside the car before and after the condition to control for outdoor ambient contributions. Each experimental session began with participant completing a brief 2-min questionnaire.