**Abbreviations**

VAR: vector autoregression, GA: genetic algorithm, FFNN: feedforward neural network, MAE: mean absolute error, sMAPE: symmetric mean absolute percentage error, RMSE: root-mean-square error, MAE: mean absolute error, PM2.5: fine particulate matter with a diameter of 2.5 μm, PM10: fine particulate matter 10 micrometers or less in diameter, SO2: sulfur dioxide, NOx: nitrogen dioxide, BP: backpropagation.
