Let's review............Two independent government labs measured air quality for the secondhand smoke trace element nicotine* and obtained the following results. (Their purpose was to prove how hazardous secondhand smoke is, however the results prove quite the contrary).
St. Louis Park, MN. Environmental Health Dept, as well as the California EPA tested air quality for nicotine* levels in the identical manner.
SLP results were 1 - 33 micrograms/ cu. M. in other words 500 - 15 times safer than OSHA requires; the median reading was 152 times safer than OSHA requirements. (measurement of indoor air quality in all bars/ restaurants which allowed smoking in 2004 before smoking bans were in place)
CA EPA results 0.01 - 5 micrograms / cu. M. in other words 50,000 - 100 times safer than OSHA requires (measurement of outdoor air quality in smoking areas) results are at bottom of pg. 3 hyperlink.
OSHA permissible exposure limit level for nicotine* is 0.5 milligrams / cu. M which equals 500 micrograms / cu. M
* (As per air quality researchers) Nicotine is the only unique or "trace" chemical in secondhand smoke. If you measured for formaldehyde, the carpet and other interior sources of formaldehyde would corrupt the test result, fomaldehyde is formed naturally in our atmosphere due to photochemical oxidation. Benzene is given off from burning foods in the kitchen or diesel exhaust outdoors so again a false reading would be obtained. Therefore, nicotine is the ideal chemical to measure for to determine secondhand smoke concentrations in the air. And then our comparison to OSHA guidelines is the logical manner in which to determine if secondhand smoke levels pose a health hazard, as you can see they do not.
Update 2010, additional AQ tests prove secondhand smoke "health hazard" claims are bogus: