To obtain objective measures of tobacco smoke concentrations and dimensions of the working areas, a single trained technician visited the work site on three occasions. During a visit, the technician (1) measured the dimensions of the work space, (2) counted the co-workers within a 60-foot radius of the subjects primary work area, (3) recorded the number of individuals frequenting the area during an entire 8-h workday and noted those who smoked, and (4) on three different occasions (separated by at least 30 days) placed a recording CO analyzer on the subjects desk. buy yasmin online
The CO levels were recorded continuously for 24 h. Results from the three days were then averaged. The CO analyzer (Ecolyzer, Energetics Science, Elmsdorf, NY) was calibrated in the laboratory and at the work site and found to have plus or minus 2 percent reproducibility and a plus or minus 2 percent accuracy at a level between 0 to 50 ppm. Of the 80 working areas tested for CO concentrations, none was located within 1 mile of a freeway, all were located on well traveled city streets and 71 were air-conditioned. No attempt was made to determine direction of the circulation of refrigerated air or the exact air exchange. Building codes required a minimum of five to six complete air exchanges per hour.