Table 2

Summary of approaches for measuring environmental markers of secondhand smoke by chemical analyte and sampling method

Chemical analyte references of representative studies	Sampling method^*	Comments
Airborne markers
Nicotine (vapour phase)5 29–33	Active, adsorbent-based; integrated Passive, filter-based; integrated	Tobacco specific Majority of nicotine in secondhand smoke (SHS) is vapour phase Widely used tracer for SHS mixture of chemicals
Respirable particulate matter15 31 32 34–37	Direct reading Active, filter based	Non-specific, many other indoor and outdoor sources Largest component of SHS Most particles in SHS are <1 micron in diameter
Carbon monoxide22 29 32 36 38–40	Direct reading	Non-specific, many other sources, particularly outdoor air Used in early SHS studies
3-Ethenlypyridine (3-EP)30 34 41–50	Active, adsorbent based Passive, filter based	Tobacco specific, pyrolysis product of nicotine Vapour phase Levels are typically lower than nicotine
Polycyclic aromatic hydrocarbons22 34 51–59	Direct reading Active: integrating Passive: integrating	Class of hazardous chemicals, some of which are carcinogens Can be measured in particle and/or vapour phase Non-specific Sampling and wet laboratory analysis is expensive
Tobacco-specific nitrosamines51 60–62	Active: integrating	Tobacco specific Potent lung carcinogen Limited data on indoor air in field settings
Other components31 40 43 51 56 59–61 63–66 Nitrogen oxides Aldehydes Metals VOCs	Various active and passive methods	Not tobacco specific, many other indoor and outdoor sources
Surface markers
Nicotine67–73	Dust vacuum samples Surface wipes	Tobacco specific Measure of long-term exposure May be particularly relevant for children's exposure

↵* ‘Direct reading’ refers to the sampling and measurement of an analyte in real time. ‘Integrating’ refers to the collection of a sample over some defined period of time, for which a time-weighted average concentration can be estimated. Active sampling refers to the use of a pump to draw air through a collection device. Passive sampling relies on diffusion.