Exposure to secondhand smoke (SHS) is harmful and hazardous to the health of the general public. A large body of research has been conducted in this topic, and great efforts have been made to prevent people from being exposed to SHS. Legislation on restricting smoking in workplaces and many public places has also been increasing. However, tobacco industries have been fighting against smoking bans in restaurants and bars with multiple strategies, which has led to the current situation that smoking bans in restaurants and bars usually lag behind other environments in many countries. As of January 2012, a total of 66 nations worldwide have enacted a 100% smoke-free law in workplaces and hospitality venues, while only 46 of the 66 include both restaurants and bars, and more than 90% of the world population can't enjoy smoke-free restaurants and bars. In addition, tobacco industries have made continuing efforts to remove existing smoking bans, and such efforts are sometimes successful. For example, as of October 2011, 15 U.S. municipalities that had adopted effective smoke-free laws subsequently repealed, weakened, or postponed them due to such efforts.
This dissertation aims to quantify SHS exposure and the attendant health risks, morbidity and mortality, among restaurant and bar servers and patrons, to provide scientific evidence on whether SHS exposure in restaurants and bars can be ignored and whether restaurants and bars should be exempted from smoking bans. The dissertation consists of seven chapters. Chapter 1 presents the general background, Chapters 2 and 3 focus on quantifying SHS exposure in restaurants and bars by workers and patrons; Chapter 4 evaluates the efficacy of different smoking policies adopted to reduce SHS exposure in restaurants and bars in Beijing China; and Chapters 5 and 6 assess the excess heath risks, morbidity and mortality, due to SHS exposure in restaurants and bars, and the last chapter summarizes the findings and conclusions from the previous five chapters.
The study in Chapter 2 applies multiple approaches to assess restaurant and bar servers' and patrons' exposure to SHS two years after the implementation of the governmental smoking restriction in Beijing, 2010. Of the 79 restaurants and bars monitored in the study, 37 (47%) nominally prohibited smoking, and 14 (18%) restricted smoking to designated sections. A total of 121 visits were made during peak-patronage times, and smoking was observed in 26 (51%) of these nominal nonsmoking venues or sections. Patrons were exposed to a median (interquartile range IQR) of 27 (4-93) µg/m3 of fine particulates derived from SHS (SHS PM) and a median (IQR) of 1.53 (0.69-3.10) µg/m3 of airborne nicotine during their visits. For servers, continuous real-time sampling of SHS PM and sequential area sampling of airborne nicotine, for more than 24 hours in two restaurants, showed obvious spikes of SHS concentrations during peak-patronage times, and SHS concentrations remained high during intervals between peak-patronage times or in evenings due to staff smoking. Servers were exposed to a median (IQR) of 2.62 (1.22-5.40) µg/m3 of airborne nicotine during their day-time working hours by one-day active personal sampling, and 1.83 (0.92-3.21) µg/m3 of airborne nicotine during a whole week by week-long passive sampling. Nonparametric Kruskal-Wallis rank tests of SHS concentrations by different nominal smoking policies showed statistically significant difference of peak-patronage-time SHS PM and airborne nicotine concentrations, while no statistically significant differences of one-day average nicotine concentration by active area or personal sampling, or of week-long average nicotine concentration by passive sampling. Comparison of results by different sampling approaches showed that both measured SHS PM and airborne nicotine concentrations were significantly related to observed active smoker activities. A slope of 17 µg/m3 of SHS PM per one µg/m3 of nicotine was observed. Time-weighted nicotine concentrations by one-hour peak-patronage time area sampling were higher than those by one-day area sampling and by week-long area sampling; and results of peak-patronage-time sampling could explain about half of the variance of the results by the latter two sampling approaches. One-hour peak-patronage-time area nicotine sampling results were very close to one-day personal nicotine sampling results. Thus, peak-time area sampling is a feasible and also a reasonably accurate way to access patrons' exposure to SHS during their short-term visits and servers' exposure during their full shifts.
Chapter 3 develops and evaluates a mass balance model to predict SHS concentrations in restaurants and bars in China during peak-patronage times. The model is based on field data from an intensive study, with field monitoring of SHS concentrations in a representative sample of Minnesota restaurants and bars during representative peak-patronage times, and field data from existing studies of Chinese restaurants and bars. The model could predict SHS PM concentrations reasonably well, but not so well for airborne nicotine concentrations. Using the model and Monte Carlo simulation, the mean (SD) of simulated SHS PM concentrations was predicted to be 135 (182) μg/m3, 90 (129) μg/m3, and 49 (79) μg/m3 in restaurants with smoking allowed everywhere, designated smoking sections of restaurants, and designated nonsmoking restaurants, respectively. Predicted SHS concentrations in bars were about two times as in restaurants with the same smoking policy. These predicted concentrations were used to assess the health risks for both servers and patrons in Chapter 6.
Chapter 4 uses field data collected in three previous studies from 2006 to 2008 and the study conducted in 2010, which is presented in Chapter 2, to evaluate the efficacy of different smoking policies adopted in Beijing restaurants and bars during this time period. There were significant overlaps of sampling venues included in each year. In 2006, all voluntary smoking bans in restaurants and bars were completely self-motivated by owners, and in 2007, they were encouraged by the government. Less than 20% of restaurants and bars prohibited or restricted smoking in 2006 or 2007. This indicates that both the self-motivated and governmental encouraged voluntary smoking bans are rarely adopted; thus, voluntary smoking bans cannot protect people from SHS exposure in restaurants and bars. When the Beijing government started to require smoking restrictions in restaurants and bars in 2008, more than 80% of venues did so as required; in these venues, the active smoking rate of patrons decreased, while no significant changes were observed in venues without any policy changes. However, some venues stopped prohibiting or restricting smoking two years later in 2010, resulting in less than 60% restaurants and bars nominally prohibited or restricted smoking, showing non-continuous enforcement by the government and decreasing compliance by venue owners. Though SHS PM concentrations in Beijing restaurants and bars decreased after the governmental smoking restriction in both 2008 and 2010, compared to those in 2006 and 2007, this happened in all the venues followed up with, regardless of the policy changes. In 2010, two years after the smoking restrictions, both SHS PM concentrations and active smoking rates in restaurants and bars were higher than in 2008, regardless of the changes in smoking policy. The similarity of SHS levels experienced by servers of restaurants and bars with different nominal smoking policies during their full shifts in 2010 also showed poor enforcement and compliance of the restrictions two years after the implementation.
Chapters 5 and 6 estimate the health risks and excess morbidity and mortality caused by SHS exposure in restaurants and bars in Minnesota, in the U.S., and in China. Intensive field monitoring of SHS exposure in a representative sample of 65 Minnesota restaurants and bars, for multiple times in each venue, showed that more than 80% of patrons were exposed to SHS concentrations above the threshold of eye and nasal irritation during more than 80% of their visits. Patrons' and servers' lifetime excess risk (LER) of lung cancer death (LCD) due to SHS exposure in restaurants and bars in both Minnesota and in China was well above the acceptable level of 1×10-6. And this was true even for patrons who visited designated nonsmoking sections only for about 1.5 hours a week in their lifetime. The LER can be much higher for patrons who visit restaurants and bars more often, or for patrons who also visit smoking sections or venues allowing smoking everywhere. As for servers, their LER of LCD or asthma initiation (estimated for Minnesota and U.S. restaurant and bar servers only) could be higher than the significant risk of 1×10-3, considered an unsafe level by the U.S. Occupational Safety and Health Administration (OSHA). In the population level, SHS exposure in restaurants and bars was estimated to cause three LCDs and 32 ischaemic heart disease (IHD) deaths per year among the general nonsmoking population, and 53 new asthma cases per year among nonsmoking servers in Minnesota, 214 LCDs and 3001 IHD deaths per year among the general nonsmoking population, and 1420 new asthma cases per year among nonsmoking servers in the U.S. This death toll was predicted to be 1325 LCDs and 1525 IHD deaths a year in China.
In all, restaurants and bars are major employers, and they are also important public places for the general population. This dissertation shows that both servers and patrons are exposed to high concentrations of SHS in restaurants and bars, and the attendant health risks, morbidity, and mortality are too significant to be ignored. Thus, to protect people from the health hazards of SHS exposure, restaurants and bars should not be exempted from any smoking bans. The only effective way is to create 100% smoke-free environments by comprehensive smoking bans, and just passing a smoking ban is not enough, while full enforcement and compliance is extremely important.