Unrecognized pollution by inorganic condensable particulate matter in the atmosphere

Protecting the population from aerosol pollution relies on forecasts using models with aerosol composition, yet the respective contributions of aerosol components are poorly known. In particular, the contribution of inorganic condensable particulate matter (PM) to aerosols is likely to be underestimated in most models because condensable particulate matter exceeds the amount of filterable particulate matter in emissions from stationary combustion sources. Moreover, condensable particulate matter is rarely included in current emission inventories. Here, we estimated the emissions of inorganic condensable particulate matter from stationary combustion sources based on monitoring information in China. Then we modeled the contributions of condensable particulate matter to simulated inorganic aerosols, e.g., sulfate, ammonium, and nitrate by designing a series of sensitivity simulation scenarios. The results show that the estimated emissions of inorganic components over mainland China are increased about five times after including inorganic condensable particulate matter, for both 2014 and 2017. Specifically, taking into account the inorganic condensable particulate matter, increased the average concentrations of sulfate by 104%, ammonium by 10%, nitrate by 11%, and PM_2.5 by 21% for the Hangzhou site in December 2017. Similarly, the simulated average daily concentrations of sulfate from December 3 to 31, 2017, more than doubled, increasing from 3.17 to 8.41 μg m⁻³ for Gucheng, 7.70 to 16.75 μg m⁻³ for Chengdu, 4.08 to 9.43 μg m⁻³ for Lin’an, and 3.19 to 7.22 μg m⁻³ for Dalian.