Beijing is one of the most polluted cities in the world. However, the “Air Pollution Prevention and Control Action Plan” (APPCAP), introduced since 2013 in China, has created an unprecedented drop in pollution concentrations for five major pollutants, except O3, with a significant drop in mortalities across most parts of the city. To assess the effects of APPCAP, air pollution data were collected from 35 sites (divided into four types, namely, urban, suburban, regional background, and traffic) in Beijing, from 2014 to 2018 and analyzed. Simultaneously, health-risk based air quality index (HAQI) and district-specific pollution (PM2.5 and O3) attributed mortality were calculated for Beijing. The results show that the annual PM2.5 concentration exceeded the Chinese national ambient air quality standard Grade II (35 μg/m3) in all sites, ranging from 88.5 ± 77.4 μg/m3 for the suburban site to 98.6 ± 89.0 μg/m3 for the traffic site in 2014, but was reduced to 50.6 ± 46.6 μg/m3 for the suburban site, and 56.1 ± 47.0 μg/m3 for the regional background in 2018. O3 was another most important pollutant that exceeded the Grade II standard (160 μg/m3) for a total of 291 days. It peaked at 311.6 μg/m3 in 2014 for the urban site and 290.6 μg/m3 in 2018 in the suburban site. APPCAP led to a significant reduction in PM2.5, PM10, NO2, SO2 and CO concentrations by 7.4, 8.1, 2.4, 1.9 and 80 μg/m3/year respectively, though O3 concentration was increased by 1.3 μg/m3/year during the five-years. HAQI results suggest that during the high pollution days, the more vulnerable groups, such as the children, and the elderly, should take additional precautions, beyond the recommendations currently put forward by Beijing Municipal Environmental Monitoring Center (BJMEMC). In 2014, PM2.5 and O3 attributed to 29,270 and 3,030 deaths respectively, though in 2018 their mortalities were reduced by 5.6% and 18.5% respectively. The highest mortality was observed in Haidian and Chaoyang districts, two of the most densely populated areas in Beijing. Beijing’s air quality has seen a dramatic improvement over the five-year period, which can be attributable to the implementation of APPCAP and the central government’s determination, with significant drops in the mortalities due to PM2.5 and O3 in parallel. To further improve air quality in Beijing, more stringent regulatory measures should be introduced to control volatile organic compounds (VOCs) and reduce O3 concentrations. Consistent air pollution control interventions will be needed to ensure long-term prosperity and environmental sustainability in Beijing, China’s most powerful city. This study provides a robust methodology for analyzing air pollution trends, health risks and mortalities in China. The crucial evidence generated forms the basis for the governments in China to introduce location-specific air pollution policy interventions to further reduce air pollution in Beijing and other parts of China. The methodology presented in this study can form the basis for future fine-grained air pollution and health risk study at the city-district level in China.