A novel air quality early-warning system is developed for cities in China.
A hybrid model named ICEEMD-WOA-SVM is proposed for forecasting major pollutants.
The fuzzy framework is used to transform forecast results into air-quality forecasts.
A novel deciding weight method is proposed based on leave-one-out strategy and WOA.
The results are validated well in Taiyuan, Harbin and Chongqing, China.