# The Calculated Circadian Effects of Light Exposure from Commuting
## 2 Materials and Methods
### Calculations of the Circadian Effects of Lights
#### 2.2.2 Circadian Stimulus
\begin{table}
\begin{tabular}{l c c c c c c c c c c c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Illuminance**} & \multicolumn{10}{c}{**\(\alpha\)-Opic Irradiance (W/m\({}^{2}\))**} & \multicolumn{10}{c}{**Circadian**} & \multicolumn{3}{c}{**Equivalent**} \\  & \multicolumn{3}{c}{**(Lux)**} & \multicolumn{10}{c}{**\(\alpha\)-Opic Irradiance (W/m\({}^{2}\))**} & \multicolumn{10}{c}{**\(\alpha\)-Opic Irradiance (W/m\({}^{2}\))**} & \multicolumn{10}{c}{**\(\alpha\)-Opic Irradiance (Unitless)**} & \multicolumn{10}{c}{**\(\alpha\)-Opic Irradiance (Unitless)**} \\  & & \multicolumn{3}{c}{**S-Cone**} & \multicolumn{3}{c}{**M-Cone**} & \multicolumn{3}{c}{**L-Cone**} & \multicolumn{3}{c}{**Rhodopic**} & \multicolumn{3}{c}{**Melanopic**} & \multicolumn{3}{c}{**Lux)**} \\  & **Mean** & **SD** & **Mean** & **SD** & **Mean** & **SD** & **Mean** & **SD** & **Mean** & **SD** & **Mean** & **SD** & **Mean** & **SD** \\ \hline
**Driving** & & & & & & & & & & & & & & & & & \\
**Sunny** & 819 & 711 & 0.52 & 0.44 & 1.17 & 1.01 & 1.33 & 1.15 & 1.07 & 0.92 & 0.97 & 0.83 & 0.40 & 0.25 & 817 & 702 \\
**Cloudy** & 733 & 382 & 0.47 & 0.25 & 1.04 & 0.55 & 1.19 & 0.62 & 0.96 & 0.50 & 0.87 & 0.46 & 0.50 & 0.06 & 734 & 388 \\
**Total** & 793 & 630 & 0.51 & 0.40 & 1.13 & 0.90 & 1.28 & 1.02 & 1.03 & 0.82 & 0.94 & 0.74 & 0.43 & 0.21 & 792 & 624 \\
**Train** & & & & & & & & & & & & & & & & \\
**Sunny** & 2639 & 2344 & 1.93 & 1.66 & 3.77 & 3.33 & 4.29 & 3.82 & 3.52 & 3.08 & 3.23 & 2.83 & 0.59 & 0.09 & 2722 & 2380 \\
**Cloudy** & 336 & 272 & 0.19 & 0.21 & 0.45 & 0.39 & 0.54 & 0.44 & 0.36 & 0.35 & 0.31 & 0.32 & 0.25 & 0.16 & 260 & 270 \\
**Total** & 938 & 1582 & 0.64 & 1.15 & 1.32 & 2.26 & 1.52 & 2.58 & 1.19 & 2.12 & 1.07 & 1.95 & 0.34 & 0.21 &Box plots of the calculated _CS_ and _EML_ values for the three modes of commuting under the two weather conditions are shown in Figure 5. One-way ANOVA tests (\(p<0.05\)) of _CS_ and _EML_ were performed in MATLAB to determine whether there are statistically significant differences between the different modes of commuting in different weather conditions. Any significant differences (\(p<0.05\)) are denoted with asterisks in Figure 5. The average _CS_ and _EML_ values are shown in Table 4. The suggested desired criterion of the proposed method is that the average _CS_ and _EML_ values are  
\(CS\) is 0.3, with the condition that the light exposure is one hour in duration [12; 32; 34; 35]. When the \(CS\) value is over 0.3, people who are exposed to such lighting conditions will have better daytime alertness and sleep quality [12; 32; 34; 35]. As the average commuting time of employed Australians was one hour (66 min in mainland capital cities, and 48 min in others) [14], 0.3 is used here. As shown in Table 4, the average \(CS\) value for riding trains in cloudy conditions (0.25) is slightly below the desired criterion (0.3), but others are all above it. The suggested value of the _EML_ depends on the space. For example, 200 melanopic lux is the recommended minimum level for a work area [19]. Although there is no recommended criterion for commuting, 200 melanopic lux is applied here, since the purpose of this study is to analyze daylight's impact on people while they are commuting, before they spend the rest of the day at their workplaces. As shown in Table 4, all average _EML_ values exceed the _EML_ recommended value (200 melanopic lux), including riding trains in cloudy conditions (260 melanopic lux). As shown in Table 4, the calculation results for \(\alpha\)-opic irradiance and _EML_ show a consistent trend--the average values for sunny conditions are all higher than the average values for cloudy conditions, which suggests that commuting on sunny days results in greater circadian impacts than traveling on cloudy days. For walking and traveling by train, these differences were statistically significant, but the differences between driving in  
Figure 5: Box plots of calculated CS and EML values for the three modes of commuting in sunny and cloudy conditions: (**a**) CS; (**b**) EML.