How Far Does Tobacco Smoke Travel Outdoors? (2026) Where the "7 Metres" Figure Comes From

The figure, and the hedge attached to it

The most frequently cited public-sector statement in Japanese on this question comes from Gamagori City, which writes that even in windless conditions tobacco smoke is said to spread at least seven metres in radius (source: https://www.city.gamagori.lg.jp/site/hokencenter/judokituen-husego.html). Two things are worth noticing. First, "even in windless conditions" frames seven metres as the calm-weather baseline, not a ceiling. Second, the page says "is said to" — the municipality is itself signalling that this is not a settled measurement. We keep that hedge rather than rewriting it as a flat assertion.

You will sometimes see the same claim quoted as "fourteen metres in diameter". That is the same number restated — seven metres of radius is fourteen metres across — not a second, independent finding. Keeping radius and diameter straight avoids a good deal of confusion when the figure gets passed around.

What this figure is not is a safe distance. We could not identify any public standard specifying a distance at which outdoor secondhand smoke exposure ceases to matter. Outdoor dispersion depends on wind direction and speed, terrain, the layout of buildings, and how many people are smoking, so no single number can carry that weight. Questions about your own health should go to a medical professional.

Seven metres also turns up in an actual ordinance

Arriving from a different direction, a comparable distance appears in law. The Tokyo Metropolitan Ordinance on Protecting Children from Secondhand Smoke, in force since 1 April 2018, provides that a person intending to smoke shall endeavour to prevent children's exposure to secondhand smoke on the street within seven metres of the outer perimeter of paediatric or paediatric dental hospitals and clinics and comparable facilities (source: https://www.reiki.metro.tokyo.lg.jp/reiki/reiki_honbun/g101RG00004895.html). The same ordinance asks people not to smoke in a room shared with children at home, not to smoke in a car carrying children, and to take care around parks, playgrounds, schools and childcare facilities. Every provision is framed as an effort obligation, and the ordinance text carries no penalty provisions.

Why outdoors becomes a question of distance at all

Indoors, the question barely arises: the revised Health Promotion Act, fully in force since 1 April 2020, draws lines by facility type. Outdoors and on private property, however, that smoking ban generally does not apply outside designated no-smoking zones. What applies instead is Article 27, which requires anyone smoking to have regard to their surroundings so as not to cause unwanted secondhand smoke (source: e-Gov https://laws.e-gov.go.jp/law/414AC0000000103). Article 27 specifies no distance. Because it specifies none, the outdoor question becomes one of position, wind and foot traffic — and judging those requires knowing where smoking actually happens. The full legal picture is set out in our explainer on secondhand smoke and the basic rules.

What to do with this in practice

• Check where designated smoking spots are around your destination, transfer stations and meeting point before you set out
• Where a station or mall has several exits, take the one furthest from the smoking spot
• On windy days, pick a route that does not pass downwind of a smoking area
• Name a meeting point away from smoking spots rather than one beside them
• The longer you plan to stay somewhere — a bench, a plaza, a terrace seat — the more checking in advance pays off
• Indoors, read the signage at the entrance before going in

You can check where designated smoking areas are on the MottoSuitai smoking area map. It was built so that people who smoke can find a legitimate place to do so, but it works just as well read the other way round, as a map of places to keep away from. The same information serves both groups, which is why this topic is better treated as shared knowledge than as a dispute. Step-by-step routines are in our practical guide to avoiding secondhand smoke in town, and considerate practice from the smoker's side is covered in our etiquette guide for people who smoke.

What this article deliberately leaves out

We do not state a safe distance, because no such public standard could be confirmed. We do not compare the constituent levels of mainstream and sidestream smoke, and we do not give a multiplier for several people smoking at once, because neither could be verified in a primary public source at the time of writing. Municipal street-smoking penalties differ locally and are not stated here — check the official site for the area you are visiting. This is a third-party summary as of August 2026, it is not medical advice, and it is not written to criticise people who smoke within the rules.