Tobacco Education Center

Outdoor Smoking Limits are Scientifically Justifiable
Simon Chapman has argued that smoking should not be banned in outdoor public venues such as hospital patios, beaches, and outdoor sporting areas, and this might also encompass building entrances, waiting lines for cinema tickets, and outdoor cafés. However, failure to ban smoking in such venues may expose nonsmokers to secondhand smoke (SHS) levels as high or higher than received in indoor spaces where smoking is unrestricted.

The reality of atmospheric dispersion of SHS outdoors is this:
Individual cigarettes are point sources of air pollution; smoking in
groups becomes an area source. Outdoor air pollutants from individual
point sources are subject to plume rise if the temperature of the smoke
plume is hotter than the surrounding air; however if the plume has a
small cross-section, as for a cigarette, it will rapidly cool and lose
its upward momentum, and then will subside as the combustion particles
and gases are heavier than air. Thus, in the case of no wind, the
cigarette plume will rise to a certain height and then descend, and for
a group of smokers, for example sitting in an outdoor cafe, on a
hospital patio, or in stadium seats, their smoke will tend to saturate
the local area with SHS.

In the case where there is wind, the amount of thermally-induced
plume rise is inversely proportional to the wind velocity -- doubling
the wind velocity will halve the plume rise. In this case, the
cigarette plume will resemble a cone tilted at an angle to the
vertical. The width of the cone and its angle with the ground will
depend upon the wind velocity: a higher wind will create a more
horizontal cone, a smaller cone angle, and a higher concentration of SHS
for downwind nonsmokers. If there are multiple cigarette sources, the
downwind concentrations will consist of multiple intersecting cones,
i.e., overlapping plumes. As the wind direction changes, SHS pollution
will be spread in various directions, fumigating downwind nonsmokers.
SHS contains a large quantity of respirable particles, which can cause
breathing difficulty for those with chronic respiratory diseases or
trigger an asthmatic attack in those with disabling asthma. For the
rest of us nonsmokers, SHS causes eye, nose, and throat irritation, just
like any other noxious outdoor fume such as bus exhaust. Hospital
orderlies, sports spectators, outdoor cafe aficionados, and beachgoers
might have to be restricted to the ranks of the non-asthmatic.

Have you ever had a dinner in an outdoor cafe in Paris, Athens, Las
Palmas, or Salt Lake City spoiled by smokers at adjacent tables? Have
you ever had to move your blanket on a public beach because someone
suddenly started smoking upwind, replacing clean salt air with
irritating smoke? Smoking has no social value other than to create
unnecessary work for physicians, and windfall profits for morticians.
Even if outdoor secondhand smoke were no more hazardous than secondhand dog excrement stuck to the bottom of a shoe, in many places laws require dog owners to avoid fouling public areas. Is this too much to ask of smokers?

James Repace, MSc., Physicist
Secondhand Smoke Consultants
101 Felicia Lane
Bowie, MD 20720, U.S.A.

phone: 301-262-9131
fax: 301-352-8457