Table 4. NO₂ 2019 model performance statistics.

The Prophet model forecasted 2019 values on an hourly basis, which was compared to actual values over a 5 day, 15 day, 1 month, and 1 year period. Units for MSE, RMSE, and MAE are ppm. The MAE was on average 0.0128 ppm away from the actual value after 5 days and as the time increased away from the known values, the error decreased and then increased.

Time	MSE	RMSE	MAE	Coverage
5 Days	2.64 × 10−4	1.63 × 10−2	1.28 × 10−2	79.0%
15 Days	2.57 × 10−4	1.60 × 10−2	1.27 × 10−2	79.5%
1 Month	2.53 × 10−4	1.59 × 10−2	1.26 × 10−2	79.7%
6 Months	2.54 × 10−4	1.59 × 10−2	1.26 × 10−2	78.7%
1 Year	2.64 × 10−4	1.62 × 10−2	1.29 × 10−2	77.7%