a first embodiment of the present invention will be explained below with reference to figures . fig1 is a schematic view showing a structure of an automobile on which an air purifying device for a vehicle according to the embodiment is applied . the air - purifying device for a vehicle is applied on an automobile 2 comprising an internal combustion engine 4 as a power unit . the exhaust gas discharged from the internal combustion engine 4 contains hc and nox . ozone is produced by photochemical reaction between hc and nox as reactants . therefore , the air - purifying device for a vehicle is applied on the automobile 2 comprising the internal combustion engine 4 , the ozone is purified while the automobile 2 is traveling , and thus , the damage to the environment caused due to the automobile 10 can be reduced , in the automobile 2 , a radiator 6 is arranged on the front side of the internal combustion engine 4 . a capacitor 10 of an air conditioner is arranged on the front side of the radiator 6 . a radiator fan 8 is mounted on the reverse side of the radiator 6 . while the automobile 2 is traveling , the atmospheric air is taken in from a bumper grill 12 on a front surface of the automobile 2 . the taken air passes through the capacitor 10 and the radiator 6 to be discharged to the rear side . even while the automobile 2 is stopping , an air flow passage from the bumper grill 12 through the capacitor 10 to the radiator 6 is formed by the revolution of the radiator fan 8 . fig2 is a schematic view culled from the automobile 2 and showing a part especially associated with the air - purifying device for a vehicle in the embodiment . in the air - purifying device for a vehicle , with the structure shown in fig2 , an ozone purifier 20 including activated carbon is coated on the radiator 6 and pm collectors 22 and 24 are coated on the capacitor 10 and the bumper grill 12 respectively . the ozone purifier 20 may consist of activated carbon only or may include some catalyst materials other than the activated carbon . the pm collectors 22 and 24 include activated carbon in common with the ozone purifier 20 . however , there is a clear distinction between the ozone purifier 20 and the pm collectors 22 and 24 in pore size of the activated carbon . in the air - purifying device for a vehicle , the activated carbon of the ozone purifier 20 is prepared so that its pore size is 10 nm or less , more practically , so that its mode in number concentration distribution of pore size is 10 nm or less . on the other hand , the activated carbon of the pm collectors 22 and 24 are prepared so that most of their pore sizes are distributed within a range from 10 to 1000 nm . practically , the activated carbon of the pm collector 24 located in the front with respect to the flow direction of the atmospheric air is prepared so that its pore sizes are distributed within a range from 100 to 1000 nm and the activated carbon of the pm collector 22 located in the rear is prepared so that its pore sizes are distributed within a range from 10 to 100 nm . fig3 is a graph showing an example of each distribution in pore size of the activated carbon of the ozone purifier 20 ( activated carbon for ozone purification ) and the activated carbon of the pm collectors 22 and 24 ( activated carbon for pm collection ). the abscissa of the graph shows radius of fine pores and the ordinate shows number concentration of the pores with the radius . in a case shown in this graph , the activated carbon for ozone purification is prepared so that its mode radius of pore is around 1 . 0 ( 10 å ) and the activated carbon for pm collection is prepared so that its mode radius of pores are distributed within a wide range from 1 . 0 to 1000 μm ( 10 to 10000 å ). the reason why the difference in pore size of each activated carbon is set in this manner relates to the particle size of the pm from vehicles . fig4 is a graph showing a relationship between particle size of pm from vehicles and number concentration published by national institute for environmental studies . as shown in this graph , many of particle sizes of pm from vehicles are distributed within a range from about 0 . 01 to 0 . 1 μm ( about 10 to 100 nm ) and their mode is around 0 . 05 μm ( 50 nm ). therefore , if the mode pore size of the activated carbon is prepared 10 nm or less , most of pms from vehicles can be prevented from invading into the fine pores and the clogging of the activated carbon can be suppressed . on the other hand , if the distribution of size of the activated carbon is prepared so as to include a range from 10 to 100 nm , then pms from vehicles in the atmospheric air can be collected effectively . fig5 is a schematic view showing a relationship between pore size of activated carbon and ease of invading pm into fine pores . in case of the activated carbon of the pm collector 22 or 24 , since the distribution of its pore size is prepared so as to include the distribution range of the particle size of pm , pm 30 is susceptible to invade into the fine pores shown in the left side of fig5 . on the other hand , in case of the activated carbon of the ozone purifier 20 , since its pore size is prepared so as to be smaller than the particle size of pm , pm 30 is difficult to invade into the fine pores shown in the right side of fig5 . that is , the pore size of the activated carbon of the pm collector 22 or 24 is prepared so as to let pms invade into the fine pores and enable to collect pms , while the pore size of the activated carbon of the ozone purifier 20 is prepared so as to prevent pms into the fine pores and enable to suppress the clogging . as described above , according to the air - purifying device for a vehicle , since the activated carbon of the ozone purifier 20 coated on the radiator 6 is prepared so that its mode pore size is 10 nm or less , the clogging of the activated carbon caused by pm can be suppressed and the activated carbon &# 39 ; s purifying function toward ozone can be kept at a high level . moreover , according to the air - purifying device for a vehicle , pm with 100 nm or more particle size can be collected by the pm collector 24 coated on the bumper grill 12 and pm with 10 run or more particle size can be collected by the pm collector 22 coated on the capacitor 10 . as a result of this , it becomes possible to decrease the amount of pm delivered into the ozone purifier 20 located in the rear of the pm collector 22 and 24 and to suppress the clogging of the activated carbon caused by pm more effectively . there is no limit how to adjust the pore size of the activated carbon . subsequently , a second embodiment of the present invention will be explained below with reference to figures . fig6 is a schematic view culled from the automobile 2 and showing a part especially associated with the air - purifying device for a vehicle in the embodiment . as shown in fig6 , in the air - purifying device for a vehicle , the ozone purifier 20 is coated on the surface of fins 16 of the radiator 6 , on which the pm collector 22 and 24 are additionally coated by two layers . the pore size of the activated carbon included in the ozone purifier 20 is prepared as explained in the first embodiment . the pore size of the activated carbon included in the pm collector 22 and 24 are also prepared as explained in the first embodiment . according to the air - purifying device for a vehicle , the atmospheric air delivered into the radiator 6 firstly passes through the pm collector 24 which is prepared so that pore size of the activated carbon are distributed within a range from 100 to 1000 nm and then flows into the underlying pm collector 22 . in this process , pm with 100 nm or more particle size are collected by the pm collector 24 and removed from the atmospheric air . since the underlying pm collector 22 is prepared so that pore size of the activated carbon are distributed within a range from 10 to 100 nm , pm with 10 nm or more particle size contained in the atmospheric air are collected while passing through the pm collector 22 . in this way , pm with 10 nm or more particle size contained in the atmospheric air , that is , most of pms are removed from the atmospheric air before flowing into the ozone purifier 20 . since the bottom ozone purifier 20 is prepared so that its pore size of the activated carbon is 10 nm or less , if pms are remained in the atmospheric air , the clogging of the activated carbon by the remained pms will be suppressed . therefore , according to the air - purifying device for a vehicle , as in the first embodiment , the activated carbon &# 39 ; s purifying function toward ozone can be kept at a high level . while the present invention has been described in terms of the embodiments , it is not limited to the embodiments , but extends to various modifications that nevertheless fall within the scope of the appended claims . for example , only the ozone purifier 20 may be applied on the vehicle without the pm collector 22 or 24 . moreover , the pm collector is coated on the capacitor in the first embodiment . however if the vehicle comprises a sub - radiator , the pm collector may be coated on the sub - radiator . the pm collector may be coated on at least the bumper grill , the capacitor and the sub - radiator rather than the first embodiment where the pm collectors with differential pore size are arranged back and forth . moreover , the pm collectors with differential pore size are coated by two layers in the second embodiment . however , the pm collectors may be formed by one layer . moreover , it is not limited to the radiator over which the ozone purifier and the pm collectors are recoated . the ozone purifier and the pm collectors may be additionally coated on the bumper grill , the capacitor and the sub - radiator .