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About Secondhand Smoke

How to measure SHS

Multiple approaches can be used to measure SHS, including administering questionnaires, observing smoking behavior, measuring components of tobacco smoke in the air and measuring components of tobacco smoke in the human body. A brief overview of some of these approaches are described below.

Self-report or observation
You can collect information on SHS exposure by administering self-report questionnaires or by collecting observational data. The information gathered complements the other methods used to monitor SHS exposure and is often used simultaneously.

  • Observational Monitoring: This method is broad and can be tailored to meet specific goals. In general, this method relies on inspecting the environment of interest for the presence of smoking and smoke-free polices. Sentinel observations can include counting smokers or cigarette butts, and looking for no smoking signs and/or sale of tobacco products.
  • Questionnaires: Asks participants to recall settings where they were exposed to SHS over some period of time

SHS levels in the environment
SHS levels in the air can be determined by measuring concentrations of tobacco components: toxic, airborne gases such as nicotine, arsenic, carbon monoxide and cyanide, or particles less than 2.5 microns in diameter, or PM2.5, capable of penetrating deep into the lungs.

  • Air Nicotine Monitoring: This method typically uses a passive air nicotine monitor, which is a small, lightweight, circular plastic badge containing a filter. As air passes through it, nicotine in the air is absorbed into the filter. Laboratory analysis can be conducted to determine the amount of nicotine collected. Results are reported in milligrams of nicotine per cubic meter of air.
  • Particulate Matter (PM2.5) Air Monitoring: This method uses a TSI AM 510 SidePak Personal Aerosol Monitor (or other similar devices) to measure respirable suspended particles. The SidePak uses a pump to draw air inside to measure the real-time concentration of air particles matter with aerodynamic diameter of 2.5 microns or less. PM2.5 is measured because particles of this size are easily inhaled deeply into the lungs.

SHS levels in the human body
Biological markers or "biomarkers" are substances measured as indicators of human exposure. Several different components of tobacco smoke have been measured in biological samples, such as blood, saliva, hair and toenails. Two of the most widely measured tobacco-related compounds are nicotine, the addictive component of tobacco, and cotinine, a metabolite of nicotine.

  • Hair Biomonitoring: This method measures nicotine concentrations in the hair as a biomarker for personal exposure to SHS in the environment. It can be used to measure long-term, cumulative exposure. Because human hair grows at approximately 1 cm per month, even a small amount of hair—2 or 3 cm from the scalp—can potentially represent tobacco-smoke exposure for several months.
  • Saliva Biomonitoring: Measures cotinine in the saliva, a metabolite of nicotine. Salivary cotinine is a particularly useful biomarker to measure for short-term exposure but it is not a good marker for long-term exposure to tobacco.


This project is funded by the Bloomberg Initiative to Reduce Tobacco Use and the Flight Attendant Medical Research Institute (FAMRI), developed in consultation with Roswell Park Cancer Institute and the University of Southern California, Institute for Global Health.