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Exposure to Secondhand Smoke: Effects of Proximity

Institution: Stanford University
Investigator(s): Lynn Hildemann, Ph.D.
Award Cycle: 2007 (Cycle 16) Grant #: 16RT-0150 Award: $628,932
Subject Area: Public Health, Public Policy, and Economics
Award Type: Research Project Awards

Initial Award Abstract
As people encounter smokers and smoking activity in different locations during the day, they are exposed to varying levels of air pollutants from secondhand smoke. A person’s daily level of exposure is critically important for determining the body’s intake of these pollutants and the diseases that result.

A person’s exposure depends on their distance from smokers, the number of smokers present, and physical characteristics of the location, such as the amount of ventilation and the volume of the room or setting. We have been studying how these factors work together to affect human exposure to pollutants from tobacco smoke in restaurants, homes, automobiles, and outdoor locations. Our measurements have shown that the distance from a tobacco source plays an important role in the level of exposure a person receives. When one is close to a burning cigarette, pollutant exposure is much greater than at distances farther away – this is called the “proximity effect.”

Important factors such as the effect of distance and location of a pollution source on nearby exposure have not been studied adequately, especially for tobacco smoke. The goal of this research project is to measure exposure to tobacco smoke when someone is in close proximity to a smoker, focusing on how a person’s relative location and proximity to a source of tobacco smoke affects their exposure. Human exposure at close distances is affected by the rapid and complex interactions between emitted air pollutants and the turbulent variations in air streams called “eddies” – the structure of these eddies can make pollutant exposures near a source especially high.

We have available specialized continuous air monitors that respond quickly and are ideally suited to making rapid measurements of this kind, and we also have experience building multiple sensor systems that can make measurements at many locations simultaneously and thereby characterize close-proximity exposure in detail. Once our monitoring system is set up and tested, we will conduct a number of carefully designed experiments to measure smoke exposure both indoors and outdoors versus time, examining difference distances from the source, and seeking trends that will allow us to predict exposure in other situations. Our study also will include measurements of exposure using real smokers and nonsmokers, to assess how our controlled experiments compare with “real world” smoking conditions.

The data collected by this study, along with previous exposure measurements conducted by this research group, will allow us to develop a model that predicts a person’s average daily exposure to secondhand smoke based on their daily activities. The predictions of this model will be compared with published field measurements of daily exposure. With this model, we will be able to determine which activities and/or locations are the major contributors to a person’s daily exposure to secondhand smoke.

Measuring & modeling the residential proximity effect: Investigating localized disperson of indoor air pollutants
Periodical: Epidemiology Index Medicus:
Authors: Klepeis, N, Ott, W, Hildemann, Cheng, C; Acevedo-Bolton, V; & Jiang, R ABS
Yr: 2008 Vol: 19 Nbr: 6 Abs: Pg: S222

Evaluation & calibratrion of continuous real-time particle monitors for fine particle exposure analysis.
Periodical: Epidemiology Index Medicus:
Authors: Klepeis, N, Ott, W, Hildemann, Cheng, C; Acevedo-Bolton, V; & Jiang, R ABS
Yr: 2008 Vol: 19 Nbr: 6 Abs: Pg: S219