y Consumo 2005; Villalbí 2006). However, smoking is banned only in some hospital- ity venues: Venues > 100 m2 must either be smoke-free or have a smoking section (up to 30% of the total area) physically separated by a closed door and independently ventilated; venues < 100 m2 may decide to be smoke-free or to allow smoking without restrictions. Two years after the law enactment, only an esti- mated 10–20% of such venues have banned smoking (Martín-Luengo 2007). As part of the evaluation of the impact of this law, we measured nicotine concentra- tions in the air as an indicator of SHS before the law was implemented (Sánchez-Martínez et al. 2007) and again 12 months after its implementation. In the present study we describe changes in nicotine concentrations in a variety of workplaces, including indoor offices and hospitality venues in Spain. Materials and Methods We included offices in the public administra- tion and private sectors, as well as universities and hospitality venues in the study at baseline (October–December 2005) and at follow-up 1 year later (October–December 2006) to assess changes in nicotine concentrations. Participant recruitment and sample size. We carried out this study in eight regions of Spain (Balearic Islands, Cantabria, Catalonia, Extremadura, Galicia, La Rioja, Madrid, and Valencia). In each region, we took 50 samples according to nonproportional quota sampling based on type of setting and size of hospital- ity venue (< 100 m2/> 100 m2). We selected the premises within each type of venue fol- lowing a convenience sampling based on the feasibility and accessibility of the venues to the researchers. We considered public administration offices to be offices in local, regional, and national administration. We selected one building from each level in each region and took four environmental samples from each building. In each region, we selected a uni- versity from which we took four air samples. In the private sector, we studied small (< 10 workers) and middle-size businesses (10–50 employees). In each region, we took six sam- ples (from three different buildings) in small firms and six samples (from four different buildings) in middle-size firms. In the hos- pitality sector, we selected four restaurants > 100 m2, four restaurants < 100 m2, and four discotheques/pubs in each region, tak- ing one sample in each venue. In restaurants that established separate areas for smokers and nonsmokers after the law came into force, we took samples from both areas. In public administration offices, universities, and mid- dle-size private-sector offices, samplers were placed in the reception area, corridors, offices (desk positions), and toilets. In small offices in Environmental Health Perspectives • volume 117 | number 3 | March 2009 the private sector, samplers were placed in the reception area and offices (desk positions). In restaurants, samplers were placed in the main dining room. We contacted the owners and managers of the selected facilities and venues either by tele- phone or by letter to explain the details of the study and to request permission. After obtain- ing permission, we arranged an appointment to place the samplers. Nicotine measures. We measured vapor- phase nicotine using SHS passive samplers, following the method described and validated by Hammond (1993) and used in previous studies of SHS assessment in Europe (Nebot et al. 2005). The samplers consisted of a 37-mm-diameter plastic cassette containing a filter treated with sodium bisulfate. These samplers were manipulated by instructed per- sonnel according to a common protocol and placed in all the settings studied except pubs and discotheques for 7 days. The samplers that had to hang freely in the air were not placed within 1 m of an area where there was a regular smoker or where air did not circulate (e.g., a corner, under a shelf, or buried in cur- tains). In discotheques and pubs, where the expected concentration of nicotine was higher and operating hours were mostly at night, we took samples from personal monitors for short periods ranging between 4 and 5 hr. Personal samplers were clipped to a shirt collar or lapel, with the windscreen facing out, away from the clothes. They were carried out by volunteers. For each sample, we recorded the following data: the sample’s code, region, setting, loca- tion, date and time of placement and removal, and smoking policy (smoking allowed, com- pletely banned, or partially banned in separate zones). We recorded information on sampling area, sampling volume, and ventilation in each establishment to evaluate extreme or inconsis- tent values. We assigned samples with nicotine concentrations below the quantification limit a value of 0.01 gμ/m 3, corresponding to half the value of quantification limit for one sam- ple exposed over a 1-week period. For qual- ity control purposes, blank filters were placed Table 1. Settings studied and number of samples. Setting studied Public administration Local administration Regional administration National administration Universities Private sector Small (< 10 workers) Medium (10–50 workers) Bars/restaurants > 100 m2 < 100 m2 Discotheques/pubs Total No. of samples at baseline 102 30 44 28 43 180 53 127 84 46 38 34 443 Impact of the Spanish smoking law within sampling filters (1 filter in 20) and all had nicotine concentrations below the quanti- fication limit. Nicotine analysis was conducted at the Laboratory of the Public Health Agency of Barcelona, using the gas chromatography/ mass spectrometry method. The limit of quan- tification was 5 ng per filter. We estimated the time-weighted average nicotine concentration (micrograms per cubic meter) by dividing the amount of extracted nicotine by the volume of air sampled [estimated flow rate (24 mL/min) × the total number of minutes the filter had been exposed]. Statistical analysis. We restricted the analysis to places where we took nicotine measurements both at baseline and follow-up (paired samples). Given the skewed distri- bution of nicotine concentration, we used median and interquartile ranges (IQRs) to describe the nicotine concentration by set- ting. We compared paired differences using the nonparametric Wilcoxon signed rank test. We used SPSS (version 12.0.1; SPSS, Inc., Chicago, IL, USA) for all the analyses. Results Overall, we took 443 air samples at baseline in eight regions (autonomous communi- ties) of Spain in the last trimester of 2005. We collected 398 samples (89.8%) again in the same venues at the 12-month follow-up. Table 1 shows the distribution by settings. According to the protocol, we took 162 sam- ples in offices in the private sector, 90 in pub- lic administration offices (state, region, and city administration venues), 43 in university indoor premises, 79 in bars and restaurants, and 24 in discotheques and pubs. Table 2 shows the change in nicotine con- centration in workplaces other than hospitality venues at baseline and 12 months after the law was enacted. During the study period, there was a significant reduction in nicotine concen- tration, ranging from 60% in public adminis- tration to 97.4% in private sector offices. After the law, all medians were < 0.20 gμ /m3. Table 3 shows the changes in hospital- ity sector. The values are stratified according No. of paired samples 1 year after the law 90 27 42 21 43 162 49 113 79 45 34 24 398 345