PM10, PM2.5, PM1, number and surface of particles at the child's seat when smoking a cigarette in a car

The exposure to particles was measured by a diffusion size classifier (10-300 nm) and an optical particle counter (300 nm-10 mu m) at the child's seat of a car during repeated drives on a fixed route from a suburban domestic area to a school and back. One single cigarette smoked in a car at the front seat during a 10 minute trip, lead to an increase of PM10 on the back seat by a factor of 10.5, for PM2.5 by a factor of 21.3 and for PM1 by a factor of 23.9. Concentrations dropped after opening the back door, but stayed elevated on the way back, compared to outdoor concentrations. Holding the cigarettes to the open window of the front seat did not reduce exposure on the back seat. When a second cigarette was smoked on the way back, PM10 concentrations rose again to 300 mu g m(-3). While background PM1 made up 19-39% of PM10, PM1 during smoking amounted to 78-89% of PM10. PM1 was highly correlated to particle number (mean 97,701 pt cm(-3), SD 82,537) and lung deposited surface area (LDSA, mean 270 cm(2) cm(-3), SD 229). Positioning of the cigarette at the open window did not decrease the exposure to LDSA at the child's seat. In conclusion, particles can reach exorbitant high levels at the back seat, when cigarettes are smoked in a small place like a car, even with a 2 inches open window next to the smoker at the front seat. Through smoking in cars parents can harm their or other's children severely.