
Significant variable  Unit  Variable type  Data source 

Air pollution charging fee  yuan/day·vehicle  Constant  
Air pollution control  Dmnl  Auxiliary variable  M_{1}+M_{3} 
Amount of GDP  yuan  Level  M_{1} 
Amount of motor vehicles  vehicle  Level  M_{1} 
Amount of motor vehicle trips  vehicle  Auxiliary variable  
Amount of NOx (PMx) generation  ton  Level  M_{1} 
Amount of population  person  Level  M_{1} 
Annual dissipation of NOx (PMx)  ton/year  Flow  
Annual scrapped  vehicle/year  Flow  
Attraction degree of city  %  Constant  M_{2} 
Attraction degree of the growth of vehicles  %  Auxiliary variable  M_{1}+M_{3} 
Attraction degree of vehicle trips  %  Auxiliary variable  M_{1}+M_{3} 
Birth rate  1/year  Constant  M_{3} 
Contribution rate of NOx (PMx) from vehicle  %  Constant  M_{2} 
Cost of motor vehicle trips  yuan/day·vehicle  Auxiliary variable  M_{3} 
Death rate  1/year  Constant  M_{3} 
Degree of air pollution  Dmnl  Auxiliary variable  M_{3} 
Dissipation and control rate of NOx (PMx)  1/year  Constant  M_{2} 
Graphical function of the growth of GDP  Dmnl  Auxiliary variable  M_{3} 
Growth of GDP  yuan/year  Flow  
Growth rate of motor vehicles  1/year  Auxiliary variable  M_{1}+M_{3} 
Growth of motor vehicles  vehicle/year  Flow  
Growth of population  person/year  Flow  
Growth rate of vehicle ownership  Dmnl  Auxiliary variable  M_{1}+M_{3} 
Impact factor of policy  Dmnl  Constant  M_{3} 
Net migration  person/year  Flow  
Net migration rate  1/year  Constant  M_{1}+M_{3} 
NOx (PMx) emissions  ton/year  Flow  
Per capita annual income  yuan/person  Auxiliary variable  
Per vehicle annual of NOx (PMx) emissions  ton/year·vehicle  Constant  M_{2} 
Pollution degree of NOx (PMx)  Dmnl  Auxiliary variable  M_{1}+M_{3} 
Population reduction  person/year  Flow  
Ratio of motor vehicle trips  %  Constant  M_{2} 
Scrap rate  1/year  Constant  M_{2} 
The average of net migration rate  1/year  Constant  M_{1} 
Weight ratio of PMx (NOx)  %  Auxiliary variable  M_{3} 
