Table 1.
Black carbon, ultrafine particles and nitrogen oxides concentrations and contrast between diesel and electric trains
| Exposure | Electric (n = 29) | Diesel (n = 54) | Mean difference (95% CI) |
|---|---|---|---|
| Black carbon (μg/m3) | 1.8 (0.5) | 10.3 (2.0) | 8.5 (7.9; 9.1)*** |
| Ultrafine particles from DiscMini (#/cm3) a) | 8100 (2400) | 189,200 (91,900) | 181,000 (153,700; 208,400)*** |
| Ultrafine particles from NanoTracer (#/cm3) | 9100 (3500) | 133,400 (52,100) | 124,300 (110,000; 138,500)*** |
| NOx (μg/m3) | 45 (16) | 363 (73) | 317 (297; 338)*** |
| NO2 (μg/m3) | 18 (9) | 54 (16) | 36 (31; 42)*** |
The exposure was assigned to study participants (study participants rode the trains in groups of different sizes. The exposure average levels for each calendar day were assigned to all members of the relevant group). Exposure levels in both scenarios are presented as mean and standard deviation. PM2.5, polycyclic aromatic hydrocarbons and aldehydes are not assigned to study participants, as the data were not collected throughout all the study period. a) missing values for DiscMini equipment indexed to four study persons for the exposure scenarios (n = 46 diesel and n = 25 for electric). ***p < 0.001