# Exposure to NO\({}_{2}\) and PM\({}_{2.5}\) While Commuting: Utility of Low-Cost Sensor
## 3 Results  
### Descriptive Statistics  
Table 1 reports general information on the monitoring campaign during heating and non-heating season, including trip time (min) and distance per mode of transport, as well as environmental conditions. Data present average value \(\pm\) standard deviation. Figure 2 presents box plots of average concentrations of PM\({}_{2.5}\) and NO\({}_{2}\) over a single trip (based on 1-min data from both commuters) by each mode of transport during heating and non-heating seasons. During the non-heating season, average temperatures range from about 16-19 \({}^{\circ}\)C across the three modes, while during the heating season, the temperatures drop considerably (around 8-10 \({}^{\circ}\)C), reflecting cooler conditions typical of winter. Atmospheric pressures for bicycle and vehicle travel modes are around 990 hPa, while walking shows more varia \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Bicycle** & **Vehicle** & **Walking** \\ \hline
**Non-Heating Season** & & & \\ \hline Investigated routes, N & 84 & 37 & 74 \\ Commuting time, min & 34.6 \(\pm\) 23.5 & 46.5 \(\pm\) 41.4 & 20.7 \(\pm\) 11.6 \\ Distance, km & 3.6 \(\pm\) 4.0 & 14.5 \(\pm\) 18.3 & 0.3 \(\pm\) 0.5 \\ Temperature, \({}^{\circ}\)C & 16.3 \(\pm\) 4.4 & 18.6 \(\pm\) 6.6 & 17.0 \(\pm\) 5.2 \\ Relative humidity, \% & 63.4 \(\pm\) 18.4 & 62.4 \(\pm\) 20.5 & 67.9 \(\pm\) 30.8 \\ Wind speed, m/s & 1.5 \(\pm\) 0.8 & 1.6 \(\pm\) 1.0 & 1.2 \(\pm\) 0.8 \\ Atmospheric pressure, hPa & 990.5 \(\pm\) 7.3 & 990.6 \(\pm\) 5.7 & 976.2 \(\pm\) 119.1 \\ PM\({}_{2.5}\) Air lab & 13.9 \(\pm\) 11.7 & 20.1 \(\pm\) 5.8 & 12.3 \(\pm\) 8.2 \\ NO\({}_{2}\) Air lab & 15.9 \(\pm\) 11.0 & 13.4 \(\pm\) 11.9 & 16.7 \(\pm\) 9.9 \\ PM\({}_{2.5}\) station & 15.4 \(\pm\) 7.4 & 12.5 \(\pm\) 5.0 & 16.0 \(\pm\) 12.2 \\ \hline
**Heating Season** & & & \\ \hline Investigated routes, N & 78 & 29 & 42 \\ Commuting time, min & 38.8 \(\pm\) 20.7 & 37.7 \(\pm\) 22.9 & 18.9 \(\pm\) 13.7 \\ Distance, km & 5.6 \(\pm\) 4.2 & 11.7 \(\pm\) 16.7 & 0.2 \(\pm\) 0.3 \\ Temperature, \({}^{\circ}\)C & 8.4 \(\pm\) 5.5 & 10.0 \(\pm\) 4.1 & 10.3 \(\pm\) 5.2 \\ Relative humidity, \% & 64.4 \(\pm\) 20.8 & 65.3 \(\pm\) 22.8 & 56.9 \(\pm\) 21.2 \\ Wind speed, m/s & 1.5 \(\pm\) 0.9 & 1.6 \(\pm\) 1.1 & 1.8 \(\pm\) 0.9 \\ Atmospheric pressure, hPa & 997.0 \(\pm\) 9.2 & 994.8 \(\pm\) 9.3 & 998.1 \(\pm\) 7.3 \\ PM\({}_{2.5}\) Air lab & 25.1 \(\pm\) 27.7 & 20.9 \(\pm\) 19.1 & 20.1 \(\pm\) 17.3 \\ NO\({}_{2}\) Air lab & 24.5 \(\pm\) 11.1 & 20.7 \(\pm\) 9.5 & 21.5 \(\pm\) 9.1 \\ PM\({}_{2.5}\) station & 28.6 \(\pm\) 14.3 & 24.8 \(\pm\) 18.3 & 29.1 \(\pm\) 11.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: General information on the monitoring campaign during the heating and non-heating season, including the number, time, and distance of trips, as well as environmental conditions. tion. Compared to the non-heating season, the heating season exhibited higher atmospheric pressures (995-998 hPa), which are typical for colder weather conditions. Relative humidity was relatively similar across modes (62-68%) during the non-heating season as well as for bicycles and vehicles (64-65%) during the heating season but showed a notable decrease for walking routes (dropping from nearly 68% to about 57%). Bicycle and vehicle commuters experienced similar wind speeds (1.5-1.6 m/s) during both seasons but increased noticeably for pedestrians (up to about 1.8 m/s) during the heating season. Mean values of NO\({}_{2}\) and PM\({}_{2,5}\) show statistically significant differences between the heating season and the non-heating seasons (\(p\) = 0.025 and 0.032).