“Complex pollution” usually refers to the environmental pollution phenomenon formed by the simultaneous presence of multiple pollutants in the same environment. In China, the issue of controlling the complex air pollution of fine particulate matter (PM2.5) and ozone (O3) poses a serious challenge, at present and in the future. “Complex pollution” usually refers to the environmental pollution phenomenon formed by the simultaneous presence of multiple pollutants in the same environment. In China, the issue of controlling the complex air pollution of fine particulate matter (PM2.5) and ozone (O3) poses a serious challenge, at present and in the future. Environment Phys.org – latest science and technology news stories