COVID-19 impact on the concentration and composition of submicron
particulate matter in a typical city of Northwest China
In this study, we evaluated the variations of air quality in Lanzhou, a
typical city in Northwestern China impacted by the COVID-19 lockdown.
The mass concentration and chemical composition of non-refractory
submicron particulate matter (NR-PM) were determined by a
high-resolution aerosol mass spectrometry from January to March 2020.
The concentration of NR-PM dropped by 40% from pre- to during control
period. The five aerosol components (sulfate, nitrate, ammonium,
chloride, and organic aerosol (OA)) were all decreased during control
period with the largest from secondary inorganic species (70% of the
total reduction), whereas the OA sources did not vary synchronously. OA
from coal and biomass burning remained stably from pre- to during
control period, while traffic and cooking related emissions were reduced
by 30% and 50%, respectively. The production rates for secondary
inorganic and organic aerosols were also evaluated and represented a
decreased trend from pre- to during control periods.