  Fusing satellite observations and station measurements to estimate
ground-level PM2.5 is promising for monitoring PM2.5 pollution. A
geo-intelligent approach, which incorporates geographical correlation into an
intelligent deep learning architecture, is developed to estimate PM2.5.
Specifically, it considers geographical distance and spatiotemporally
correlated PM2.5 in a deep belief network (denoted as Geoi-DBN). Geoi-DBN can
capture the essential features associated with PM2.5 from latent factors. It
was trained and tested with data from China in 2015. The results show that
Geoi-DBN performs significantly better than the traditional neural network. The
cross-validation R increases from 0.63 to 0.94, and RMSE decreases from 29.56
to 13.68${\mu}$g/m3. On the basis of the derived PM2.5 distribution, it is
predicted that over 80% of the Chinese population live in areas with an annual
mean PM2.5 of greater than 35${\mu}$g/m3. This study provides a new perspective
for air pollution monitoring in large geographic regions.
