Secondhand tobacco smoke exposure in New Zealand bars: results prior to implementation of the bar smoking ban.

AIMS

To measure secondhand smoke (SHS) levels in New Zealand bars prior to smokefree legislation enacted on 10 December 2004.

METHODS

Thirty bars were randomly selected from urban, surburban, and surrounding rural areas of Auckland, Wellington, and Invercargill. Bars were visited (on a Friday or Saturday night for a 3-hour stay between 1800 and 2400 hours) in July/August/September 2004 (winter) and again in October/November 2004 (spring). Each bar was visited by a group of 4 or 5 non-smokers participating in the study. All groups of participants spent a 3-hour block of continuous time in the bar. Saliva samples (approximately 0.5-2 mL) were provided immediately prior to entering the bar as well as 5-15 minutes after leaving the bar. Each group recorded the initial impression of air quality and ventilation, the number of observed lit cigarettes over three 10-minute intervals throughout the evening, and the number of patrons at each interval. In addition, any general comments about the venue (relevant to bar attendance or air quality on the evening) was recorded. Cotinine, the main metabolite of nicotine, was measured in saliva samples using Liquid Chromatography with tandem Mass Spectrometry (LC-MS-MS).

RESULTS

In all bars, and in all volunteers, exposure to SHS was evident. Saliva cotinine increased after 3 hours in the bar (mean increase=0.66 ng/mL, SE=0.03 ng/mL, p value of <0.0001). The 30 bars randomly selected provided a good spectrum of SHS exposures, with mean cotinine increasing by approximately 8-fold. Smaller population centres showed greater exposures to SHS. A north-south gradient of exposure was also seen (highest exposures were in Southland). Higher exposures were seen in the winter than in the spring. The objective measures of SHS exposure correlated strongly with the volunteers' subjective observation of ventilation, air quality, and counts of lit cigarettes. One exception was where objective salivary markers indicated that even "seemingly smokefree" venues with "good ventilation" produced discernable levels of SHS exposure.

CONCLUSIONS

We have utilised an objective, non-invasive scientific approach to assess SHS smoke exposure in patrons of New Zealand bars. Our results clearly indicate exposure to SHS, with regional and seasonal variation, prior to the introduction of smokefree legislation.