Particulate air pollution in transport micro-environments

Abstract

To understand the dynamics of particulate matter inside train coaches and public cars, an investigation was carried out during 2004–2006. For air-conditioned rail coaches, during peak journey times, the mean concentrations of PM₁₀, PM_2.5 and PM₁ were 44 µg m⁻³, 14 µg m⁻³ and 12 µg m⁻³, respectively. The levels fell by more than half (21 µg m⁻³, 6 µg m⁻³, and 4 µg m⁻³) for the same size fractions, on the same route, during the off-peak journeys. On the other hand, in non-air-conditioned coaches, the PM₁₀ concentrations of up to 95 µg m⁻³ were observed during both peak and off-peak journeys. However the concentrations of PM_2.5 and PM₁ were 30 µg m⁻³ and 12 µg m⁻³ in peak journeys in comparison to 14 µg m⁻³ and 6 µg m⁻³ during off-peak journeys. Over a period of four months the concentrations of PM₁₀, PM_2.5 and PM₁ in car journeys were generally similar during both morning and evening journeys with average values of 21 µg m⁻³ for PM₁₀, 9 µg m⁻³ for PM_2.5 and 6 µg m⁻³ for PM₁. However during October the average concentration of PM₁₀ was 31 µg m⁻³. An analysis of nearby fixed monitoring sites for both PM₁₀ and PM_2.5 revealed an episode of high particulate pollution over southern England during one week of October. There was no statistically significant difference between particulate matter levels for morning and evening car journeys. A statistically significant correlation was found between morning and evening PM₁₀ (0.45), PM_2.5 (0.39) and PM₁ (0.46). In train journeys, a statistically significant difference was observed for peak and off-peak levels of PM₁₀, PM_2.5 and PM₁ in air-conditioned coaches. On the other hand, in non air-conditioned coaches a significant difference was documented only for PM_2.5 and PM₁.