Table 1.

Descriptive summary of conditions

Condition	Engine on	Driving (20 min)	Window position	Air conditioner on
1	No	No	All closed	No
2	Yes	Yes	All closed	No
3	Yes	Yes	All open	No
4	Yes	Yes	Driver's window  open 18 cm	No
5	Yes	Yes	All closed	Yes

Note. Participants completed this condition by holding their cigarette next to the half-open window when not inhaling from the cigarette.