Theoretical results:
- Nearly 100 samples of PM2.5 have been analyzed in Hanoi from 2019 to 2020. The PM2.5 concentrations in the VT1-2-3 (Hoang Van Thai, Co Nhue, and Xuan La) (76.8 ± 41.3 µg/m3) was lower than those in VT4 (Dong Anh) (98.9 ± 35.6 µg/m3), and which was higher than the standard limit allowed by QCVN 05: 2013/BTNMT from 1.5 to 1.9 times. The average concentration of PM2.5 increased in the following order: summer (42.8 ± 16.3 µg/m3) < autumn (58.5 ± 20.5 µg/m3) < winter (69.8 ± 28,0 µg/m3) < spring (90.7 ± 33.2 µg/m3) in the inner city; and autumn (60.4 ± 14.9 µg/m3) < spring (76.8 ± 41.3 µg/m3) < winter (159.5 ± 50.8 µg/m3) in suburban areas.
- Ca, Fe, Mg, Zn, K and Al was the most abundant elements in PM2.5 in urban area. The average concentrations of Cd, V, Ni, Pb, Mn and Cr bounded PM2.5 inner and suburban areas were lower than the allowable values according to WHO standards and standards. Concentration of As is about 1.1 times higher than the allowable limit according to EU standards in suburban areas.
- The highest concentrations of PM2.5-bound trace metals occurred in winter or spring followed by autumn and summer. The concentration of metals in PM2.5 Hoang Van Thai, Co Nhue, and Xuan La was higher than those in Dong Anh.
- Principal component analysis with multiple linear regression (PCA/MLR) revealed that the major sources of trace elements in inner city were crust dust, traffic emisson, industrial activities, coal burning. Meanwhile, the major sources of trace elements in suburban aerea were crustal dust, fuel oil / agricultural chemicals, industrial activities, biomass burning, traffic esmission, coal burning.
Applied results:
- The PM2.5 and PM2.5-bound trace metals was conducted at four sites representative of urban, suburban of Hanoi.
- The major sources of trace elements Hanoi were crust dust, traffic emisson, industrial activities, coal burning, fuel oil / agricultural chemicals, biomass burning. | 
