How far does cigarette smoke travel outside?
The smell of one cigarette usually carries about 15 to 30 feet downwind during the day, and about 30 to 75 feet on a clear, still night. Measured smoke levels drop to background within about 13 feet, but a nose picks up the smell well beyond that.
Outdoors, smoke doesn't spread out evenly in a circle. It leaves you as a narrow ribbon that follows the wind, so someone 25 feet downwind may smell it while someone 10 feet upwind doesn't.
What the measurements show
Stanford researchers measured smoke particles around outdoor smokers. Sitting within 18 inches of someone smoking could mean as much smoke as a smoky bar, and the heaviest levels were within about 2 feet downwind. With one cigarette, levels were high within about 3 feet, dropped a lot by 7 to 13 feet, and couldn't be told apart from background air beyond about 13 feet (4 meters). With several smokers together, the elevated zone stretched to about 23 feet. Levels roughly halved each time the distance doubled, and wind direction mattered a lot.
Those are particle meters, though. The human nose notices smoke odor at levels well below what those meters detect, so the smell reaches farther than the measured smoke.
Typical smell distances for one cigarette
From Driftline's drift model, a meandering plume model like the ones used for industrial odor studies. "Reach" is how far someone downwind would likely catch whiffs now and then.
| Conditions | Reach downwind |
|---|---|
| Sunny afternoon, light breeze (5 mph) | 20–25 ft |
| Sunny, 10 mph breeze | 13–16 ft |
| Cloudy day, 10 mph | 20–30 ft |
| Windy, 20 mph | 15–20 ft |
| Cloudy night, 8 mph | 25–30 ft |
| Clear night, light wind (3 to 6 mph) | 55–75 ft |
The longer night numbers are for open ground. Among houses and in the city, buildings stir the air and the reach on clear nights is closer to 30 to 50 feet. A few people smoking together push every number out further.
Why it travels farther at night
Sun-warmed ground makes the air churn, which mixes smoke upward and thins it out quickly. On a clear night the air near the ground goes still, and smoke stays low and concentrated as it drifts. That can double or triple how far the smell reaches. A stronger wind, on the other hand, dilutes smoke faster, so the farthest drift usually comes with a light, steady breeze.
How far away should you smoke from a door or window?
Many cities and workplaces set smoke-free zones of 15 to 25 feet around entrances. Distance helps, but direction helps more: stand where the wind blows away from the door. Wind is named for where it comes from, so a south wind carries smoke north.
Does cigarette smoke travel as far as weed smoke?
Cannabis smoke usually smells stronger and carries about 1.5 to 2 times as far. See how far weed smoke smell travels.
Common questions
How far does secondhand smoke travel?
In Stanford's outdoor measurements, the heaviest exposure was within about 2 feet downwind of a smoker, with a big drop by about 6 feet. The US government's Smokefree.gov says secondhand smoke can travel up to 20 feet.
How long does cigarette smoke stay in the air outside?
Outdoors it usually clears within minutes after the cigarette goes out, faster in a breeze. Indoors it can linger for hours.
Can cigarette smoke come in through a window?
Yes, if the window is downwind and close. A screen doesn't stop it. Moving so the wind blows away from the window helps more than a few extra feet.
How far away should you smoke from a door?
Many local rules use 15 to 25 feet. To keep the smell out, also stand where the wind blows away from the door.
How sure is this?
The particle measurements are real data. The smell distances are an educated estimate from a standard drift model, since nobody has measured exactly how far people can smell smoke outdoors, and noses vary. Use them as a guide.
Open the live mapSource for the measurements: the University of Otago review of outdoor tobacco smoke research, which summarizes the Stanford studies. For adults 18+.