# Exposure to NO\({}_{2}\) and PM\({}_{2.5}\) While Commuting: Utility of Low-Cost Sensor
## 3 Results
### Considering Inhaled Doses Instead of Concentrations  
Generally, without distinguishing the mode of transport or season, the mean value of the total inhaled dose of NO\({}_{2}\) was higher for the male (32.8 \(\upmu\)g) than the female (23.9 \(\upmu\)g), and the difference was not statistically significant (\(p>0.05\)). The median in both was significantly lower than the mean (13.2 \(\upmu\)g for the male and 13.3 \(\upmu\)g for the female). The maximum values were similar for both participants, but the greater spread of values for the female participant's dose indicates greater variability in the data. For PM\({}_{2.5}\), the mean value of the total inhaled dose was twice as high for the male participant (16.8 \(\upmu\)g) as for the female (8.3 \(\upmu\)g); the difference was significant (\(p=0.004\)). The median was also higher in the male (6.6 \(\upmu\)g) than in the female participant (1.5 \(\upmu\)g) exposure, and the wide range of values for both participants confirms the presence of outliers. After separating the doses according to the mode of transport and participants (Figure 4) for both pollutants, the bicycle emerged as the mode of transport with the highest inhaled dose per trip. For NO\({}_{2}\), the mean dose inhaled by the male participant was 44.5 \(\upmu\)g (median 25.9 \(\upmu\)g), while for the female participant, 42.6 \(\upmu\)g (median 31.4 \(\upmu\)g). For PM\({}_{2.5}\), mean values were 25.3 \(\upmu\)g and 17.1 \(\upmu\)g (median 11.9 \(\upmu\)g and 3.1 \(\upmu\)g), respectively, with no statistically significant difference between the participants. In the case of both pollutants, the inhaled dose during cycling was significantly higher than in other modes of transport (\(p<0.05\)), and no statistically significant difference was observed between the dose inhaled during commuting by vehicle and walking. The doses during trips by bike were significantly higher than by vehicle and walking, which is related to higher VR for cycling (MET \(>6\)). Figure 4 shows the dose of NO\({}_{2}\) and PM\({}_{2.5}\) inhaled by the female participant and the male participant per trip (\(\upmu\)g), while Figure 5 presents the inhaled dose per kilometer traveled (\(\upmu\)g/km). It can be noted that the trend of inhaled dose per trip differs from the corresponding trend of inhaled dose per km. In the case of both pollutants, if distance is included, the highest dose per kilometer was found during walking. Without distinguishing the mode of transport or season, the mean value of the total inhaled dose of NO\({}_{2}\) was higher for the male (58.3 \(\upmu\)g/km, median 8.4 \(\upmu\)g/km) than for the female (52.2 \(\upmu\)g/km, median 14.9 \(\upmu\)g/km). For PM\({}_{2.5}\), the female inhaled higher doses per km, and the mean dose was 19.6 \(\upmu\)g/km (median 3.1 \(\upmu\)g/km). In comparison, the mean dose for the male participant was 14.4 \(\upmu\)g/km (median 4.6 \(\upmu\)g/km). The difference between the male participant and the female participant was not statistically significant (\(p>0.05\)). Gender and driving mode analysis points out that the PM\({}_{2.5}\) dose inhaled per km differs significantly between  
Figure 3: Boxplots of PM\({}_{2.5}\) by transport mode during non-heating and heating seasons. Boxes represent the 25 th to 75 th percentile. The central dark line is the median. Bars outside the box are the minimum and maximum. The cross is the mean value, and the circles are the outliers. modes of transport (\(p<0.05\)). The highest dose was inhaled while walking, while the lowest dose was for vehicles. The mean dose for NO\({}_{2}\) during walking was 141.3 \(\mathrm{\SIUnitSymbolMicro g}\)/km (median 109.1 \(\mathrm{\SIUnitSymbolMicro g}\)/km) and 77.9 \(\mathrm{\SIUnitSymbolMicro g}\)/km (median 52.9 \(\mathrm{\SIUnitSymbolMicro g}\)/km) for the male and the female participant, respectively.