May 2007
Real-Time Measurement of Outdoor Tobacco Smoke Particles
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Neil E. Klepeis, Wayne R. Ott, and Paul Switzer,
Stanford University, Stanford, CA
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AbstractThe current lack of empirical data on outdoor tobacco
smoke (OTS) levels impedes OTS exposure and risk assessments.
We sought to measure peak and time-averaged
OTS concentrations in common outdoor settings near
smokers and to explore the determinants of time-varying
OTS levels, including the effects of source proximity and
wind. Using five types of real-time airborne particle monitoring
devices, we obtained more than 8000 min worth
of continuous monitoring data, during which there were
measurable OTS levels. Measurement intervals ranged
from 2 sec to 1 min for the different instruments. We
monitored OTS levels during 15 on-site visits to 10 outdoor
public places where active cigar and cigarette smokers
were present, including parks, sidewalk cafés, and restaurant
and pub patios. For three of the visits and during
4 additional days of monitoring outdoors and indoors at
a private residence, we controlled smoking activity at
precise distances from monitored positions. The overall
average OTS respirable particle concentration for the surveys
of public places during smoking was approximately
30 g m3. OTS exhibited sharp spikes in particle mass
concentration during smoking that sometimes exceeded
1000 g m3 at distances within 0.5 m of the source.
Some average concentrations over the duration of a cigarette
and within 0.5 m exceeded 200 g m3, with some
average downwind levels exceeding 500 g m3. OTS
levels in a constant upwind direction from an active cigarette
source were nearly zero. OTS levels also approached
zero at distances greater than approximately 2 m from a
single cigarette. During periods of active smoking, peak
and average OTS levels near smokers rivaled indoor tobacco
smoke concentrations. However, OTS levels
dropped almost instantly after smoking activity ceased.
Based on our results, it is possible for OTS to present a
nuisance or hazard under certain conditions of wind and
smoker proximity.
ImplicationsThis article is the first peer-reviewed publication of systematic
measurements of OTS concentrations. The main conclusion
from these data, that OTS levels can be substantial
under certain conditions, is vital to the development of
outdoor tobacco control policy. Because adequate information
on OTS levels and human exposures has previously
been lacking, the estimation of health risks associated with
OTS has been hindered, and public discourse concerning
OTS has been impaired. The present study also has shown
that continuous, portable airborne particle monitors are
suitable in OTS investigations across a range of locations
and environmental conditions.
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