Secondhand smoke (SHS) is a major source of indoor air pollution. SHS contains a complex mixture of more than 4,000 chemicals and 50 cancer-causing agents. There is no safe level of exposure to SHS. Korea does not have comprehensive indoor smoke-free policy, although hospitals, day-care centers, kindergartens as well as elementary, middle and high schools are designated as “smoke-free buildings”. Limited information of the extent of SHS exposure in Seoul public places is available.
The purpose of this study was to assess the impact of SHS in public places in Seoul, Korea, on indoor particulate matter with 2.5 μm aerodynamic diameter or smaller (PM2.5).
Indoor PM2.5 level was measured using an aerosol spectrometer (Sidepak Model AM510, TSI Inc). Purposive sampling was used to identify the venues that allowed smoking. Indoor air quality was measured in 40 public places, including 8 restaurants, 10 cafes, 6 pub/bars, 10 billiard halls and 6 PC rooms. A central location of the venue was chosen and the direct puffs of smokers were avoided. The monitoring was continued for at least 40 minutes each place in the busiest business hours in Friday and Saturday, from December 2007 to March 2008. Outdoor level was measured to confirm no significant outdoor sources. Information on room size, number of person and number of burning cigarettes was collected.
Average size of the public places was 231.2 m3. Average number of people was 19 and average burning cigarette was 2.9. The mean of PM2.5 concentrations in the 40 places was 165 μg/m3, which was more than 4 times higher than the US National Ambient Air Quality Standard for 24 hours (35 μg/m3). The average indoor PM2.5 concentration in 3 venues with no smoking was 24 μg/m3. When indoor smoking was observed in 37 places, indoor PM2.5 concentrations ranged from 33 to 881 μg/m3, with a mean of 177 μg/m3. Among the 37 smoking places, indoor PM2.5 concentrations were 84 μg/m3 in 6 restaurants, 144 μg/m3 in 9 cafés, 108 μg/m3 in 6 pub/bars, 173 μg/m3 in 10 billiard halls, and 392 μg/m3 in 6 PC rooms. Smoking density was calculated by average number of burning cigarettes (bc) per 100 m3 of indoor volume. Average smoking density in the 40 venues was 3.4 #bc/100 m3, ranging from 0 to 39.5 #bc/100 m3. Indoor PM2.5 level was significantly associated with smoking density. When smoking density was less than 1 #bc/100 m3, indoor PM2.5 concentration was 92 μg/m3. Indoor PM2.5 concentrations were 147 μg/m3 and 241 μg/m3 when smoking densities were 1–2 #bc/100 m3and greater than 2 #bc/100 m3, respectively.
SHS can cause significantly higher indoor fine particle concentrations in Seoul public places. Reduction of exposure to SHS in public places is important for public health. The findings support the need for indoor smoke-free laws in Korea to improve indoor air quality in all public places.