Fig 1.
Schematic representation of the a) exterior and b) the most common interior layout, of the GOVA transit buses (NOVA LFS diesel bus).
Table 1.
Technical characteristics of the Aranet4Home detector and the Vitalight Mini CO2 detector.
Fig 2.
The a) Vitalight Mini CO2 detector, and the b) Aranet4 Home CO2 detector.
Table 2.
Variables measured using the ride survey, including the category and frequency of measurement per transit ride.
Table 3.
Descriptive summary of observations taken on the 250 transit trips between October 2022 and July 2023.
Table 4.
Descriptive summary of measurements taken on the 250 transit trips between October 2022 and July 2023.
Fig 3.
Spatial map representing transit route 3, which represents 89.6% of the route data. The blue line, with the blue circle markers, represents the outbound portion of the route and its stops; the orange line, with the orange triangular markers, represents the inbound portion of the route and its stops. Spatial map was reprinted, and modified, from the original version from NASA Earth Observer [52]. The map data is licensed under the Open Data Commons Open Database License (ODbL) by OpenStreetMap and its contributors [53].
Fig 4.
Daily average CO2 concentrations.
Time-series plot of the daily average CO2 concentrations, recorded by the Vitalight and the Aranet, across the nine-month study period. Seasons are separated by dashed lines.
Table 5.
Pearson correlations (r) between concentrations of CO2 measured with the Vitalight and the Aranet, and temperature, relative humidity, and number of stops with doors open, at time 1 and time 2. r2 values are in brackets.
Fig 5.
Using Pearson’s correlation, there was a strong positive relationship between CO2 concentration (ppm) as measured by the Vitalight and the Aranet at a) T1 and b) T2.
Fig 6.
CO2 concentration (ppm) as measured by the Aranet was significantly higher than the Vitalight at a) T1 and b) T2.
Fig 7.
CO2 concentration by occupancy.
CO2 concentration (ppm) was significantly affected by occupancy level at T2, according to the Kruskal-Wallis H test. Mann-Whitney U post hoc tests showed CO2 was lower at low compared to medium and high occupancy, as measured by a) the Vitalight and b) the Aranet.
Fig 8.
CO2 concentration by seating position.
CO2 concentration (ppm) was significantly affected by seating position at T1, according to the Kruskal-Wallis H test. Mann-Whitney U post hoc tests showed CO2 was higher at the back of the bus compared to the front and the middle, as measured by a) the Vitalight, and lower at the front of the bus compared to the middle and the back, as measure by b) the Aranet.
Fig 9.
CO2 concentration by window status.
CO2 concentration (ppm) was significantly higher when the bus windows were closed compared to open, as measured by a) the Vitalight, and b) the Aranet, at T1, and c) the Vitalight, and d) the Aranet, at T2, according to Mann-Whitney U tests.
Fig 10.
Summary of the three recommendations for personal risk assessment using the Vitalight to assess ventilation.