Severe air pollution events in many parts of China pose a major threat to health and ecosystems. China's air pollution is concentrated to economically developed areas, for instance Beijing-Tianjin-Hebei (BTH) and Pearl-River-Delta (PRD). The situation has received considerable attention in international and national media including its secondary societal and economic impacts such as lowered productivity, reduced investments and loss of professionals who have the choice of residing elsewhere. Large efforts are today underway from the Government to improve the situation by measures to reduce primary emissions, see Airborne Pollution Prevention and Control Action Plan (2013-2017), available at http://www.gov.cn. This will also affect secondary pollutants such as ozone (O3) and particulate matter (PM) but how and to what magnitude is uncertain. The photochemically induced secondary pollutants will add to any severe local urban air pollution but requires a very different approach for abatements. In this perspective view we will address the complexity of photochemical smog while acknowledging the urge for similar descriptions on local urban air pollution as described elsewher.