In previous work, a methodology was developed to discuss
the influence
of meteorological factors, policies, and surrounding cities on PM2.5 concentrations in a city. Two models were constructed using
Zibo City, Shandong Province, as the target city. Initially,
we improved the established PM2.5-Meteorological-Policy
(PMP) model and applied it to six other target cities in Shandong
Province. Concurrently, a novel model named the PM2.5-Interregional
(PI) model was further developed in each city to directly express
the influence of surrounding cities on the target cities. The model
construction period was from January 2014 to August 2022, with the
extended prediction period until November 2022. The results confirmed
that disparities in the spatial distribution in seasons became smaller
after the implementation of environmental policies. Moreover, two
models in each city revealed good interpretation with high adjusted R
2 values (>0.7) and lower MAPE and RMSE values
(the lowest was 5.53% and 2.57), suggesting reasonable short-term
prediction. Additionally, meteorological factors and the combined
implementation of different policy types played crucial roles in reducing
PM2.5 concentrations in all cities. Specifically, the temperature
and wind speed were negatively correlated with PM2.5 concentrations
in all models, with temperature having a stronger influence. The Law
of the People’s Republic of China on the Prevention and Control
of Atmospheric Pollution (LAPAP), implemented in 2016, had a clear
influence on reducing PM2.5 concentrations, with the highest
absolute fitted coefficient in most cities (−0.166 to −0.344).
On the contrary, the influence of temperature seemed to be more significant
compared to policies, due to the larger standardized coefficient in
each city (−0.606 to −0.864).