Complex urban air quality has long been assessed by a single (or major) contaminant, e.g., fine particulate matter (PM2.5 ), but scant attention has been given to multicontaminant air pollution, especially in countries with severe air pollution, e.g., China. We thus proposed an improved method for quantifying both single- and multicontaminant air pollution. Our approach uses China's major cities as an example, as they have an operational national urban air quality monitoring network. We found that our proposed method could remove the duplicated consideration under both single- and multicontaminant conditions, thus proving to be an improved and more accurate way to understand complex urban air pollution conditions. Our method involved monitoring three contaminants (PM2.5 , PM10 , and SO2 ) in cities in Shanxi, Shandong, Henan, and Hebei Provinces and two contaminants (PM2.5 and PM10 ) in the cities between the Yellow River and the Yangtze River, and these pollutants were the major contributors to multicontaminant air pollution. We argue that both the research community and the government should pay increased attention to multicontaminant air pollution beyond the current single major pollutant-based air pollution method when building a sustainable city. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.