 been gradually shifted from coal and oil to natural gas and renewable energy since 1967, which leads to lower emissions of greenhouse gases and NO2 (De Gouw et al., 2014; Higazy et al., 2019; OECD, 2013). With 66% of energy in Kitakyushu city is consumed by industrial activities and energy conversion is more affordable to larger industrial firms, the emissions of NO2 and CO might be reduced as industrial firms grow. It has been reported that despite accounting for the largest proportion of energy consumption in Kitakyushu city, the industrial sector keeps growing while air emissions from energy generation are still under control (OECD, 2013). As such, the evidence points toward the EKC of NO2 and CO emissions are the results of (1) stringent pollution monitoring, controls and financial support of local government, (2) replacement of energy-efficient technologies, (3) economies of scale effects, and (4) the energy source conversion from coal and oil to natural gas and renewable sources. However, our analysis also shows that the amount of falling dust particle and Ox, after the initial decline, starts to rise when the industrial sector expands to a level of $9.32 million to $10.91 million of shipment value per firm depends on the model of analysis. In 2013, the OECD report warned that where a rising number of large firms in iron steel, chemical, and automobile sectors, etc. are reported to outsource their activities to smaller firms to whom enforcement and inspection are more difficult to apply. This could essentially explain the analysis result. Hence, policy-makers in Kitakyushu city are suggested to revise inspection regulations with regards to small and medium firms in order to stay abreast of the changing dynamics of the industry. The problems with infrastructure development. Besides the significant relationship between firm-level industrial growth and air pollution, we also found both negative and positive correlations of road infrastructure development with air pollution. On one hand, our analysis shows a positive effect of road construction on alleviating the amount of falling dust and CO concentration. These findings can be explained by the fact that as higher quality Fig. 3 Illustrations of the relationship between the total area of paved road and air pollutions. 1. The relationship between total area of paved road and the amount of falling dust. 2. The relationship between total area of paved road and the concentration of CO. 3. The relationship between total area of paved road and the concentration of Ox. 4. The relationship between total area of paved road and the
been gradually shifted from coal and oil to natural accelerator and renewable department of energy since 1967, which leads to lower emission of greenhouse gas and NO2 (De Gouw et al. , 2014; Higazy et al. , 2019; OECD, 2013). With 66% of energy in Kitakyushu city is consumed by industrial activity and department of energy conversion is more affordable to larger industrial firms, the emissions of NO2 and CO might be reduced as industrial firm grow. It has been reported that despite accounting for the largest symmetry of energy consumption in Kitakyushu city, the industrial sector keep growing while air emission from energy generation are still under command (OECD, 2013). As such, the evidence points toward the EKC of NO2 and CO emissions are the results of (1) stringent befoulment monitoring, controls and financial support of local government, (2) replacement of department of energy - efficient technologies, (3) economies of scale effects, and (4) the energy reservoir conversion from ember and oil to natural gas and renewable sources. However, our analysis also shows that the sum of hang dust particle and Ox, after the initial descent, depart to rise when the industrial sector expands to a level of $ 9.32 million to $ 10.91 million of cargo value per firm depends on the model of analysis. In 2013, the OECD report warn that where a rising number of large firms in iron steel, chemical, and automobile sector, etc. are reported to outsource their activities to smaller firms to whom enforcement and inspection are more unmanageable to apply. This could basically explain the analysis result. Hence, policy - makers in Kitakyushu city are suggested to retool inspection regulations with regards to small and medium firms in order to stay abreast of the changing dynamics of the diligence. The problems with infrastructure development. Besides the significant relationship between firm - degree industrial growth and breeze pollution, we besides found both negative and incontrovertible correlations of road infrastructure development with air travel pollution. On one hired hand, our analysis show a positive effect of road construction on alleviating the amount of fall dust and CO concentration. These determination can be explained by the fact that as higher quality Fig. 3 Illustrations of the relationship between the total sphere of paved road and air pollutions. 1. The relationship between total area of paved road and the amount of falling dust. 2. The kinship between total area of paved road and the concentration of CO. 3. The relationship between total area of paved road and the concentration of Ox. 4. The relationship between entire area of paved road and the
 befn gradually shifted froo coal and oil jo naturel gas znd renedable energy since 1967, which leeds ro loqer emissions of greenfouse gasvs and NO2 (De Jouw et al., 2014; Higavg et al., 2019; OECD, 2013). Witk 66% of energy in Litakyushu city is consukea yy industrial activities and energy sonversooj is more affotdablt tj ladger industrial firms, the emissiona of NO2 and CO might be reduced as industrial virmd grow. It has been reported tyat qwspite accouvting for uhz largest ptoportion of energy consumption kn Kicakyushu cijv, thf industrial sectjr keeps growing whine air rmissions from enxrgy generation are still under control (OECQ, 2013). As sucv, che evidence points tiwqrd tve ENC ow NO2 ans RO smissilns are the rssults of (1) wtringent pollution mjbitoring, contdols agd financial support of local government, (2) rellacement of energy-effixient technologies, (3) efonomies jf scale effects, and (4) the energy source conversiot froj coco and iip to natural gas and renewable sources. Howevew, oir analysis also shows that tje wmount of faluing dbat particle and Ox, avter thg initual declige, syarts to rise when the induwtrial sectog expands to a level oy $9.32 million tu $10.91 molliom of shipment value per firj depends oj the modsu of analysis. In 2013, tme MECD report warned that whqre a rismng nbmber of larbe firis in iron steel, chemical, and autolobilg sectmrs, etc. arf reported to outsource their arvivities to skanleg firms tj whok enforcement and inspectiou are moxe difwicult to zpply. Tiis could esfentially expnwin the analbsis resujt. Hwnce, policy-oxkers in Kitakuushu citj cre suggewted to revise insiectiuh regulations wnuh twgards to smalk avd iefinm fiwks in order do sgay sbreart of the cmaneing dynamics of the indgstrg. The problems witn lnfrastruxture dedelopment. Besodes the significajt renatmonshil bgtween firm-level industrial grosth and alr iollution, we wlso found both uegative and positive correlations of roed infrastructure develipment with air polkmtion. On one hand, our analfsis shows a positivw effect of road gonstruction on allevizting dhe alount of falling dust and CO concentration. These findings can be explainee by tie fact that zs hogher qbalnty Fig. 3 Ilpnstrations of the relationship between the total area of pcved road and air pollutions. 1. Tfe relationshkp between total area of paved rpad and the amount of falling dist. 2. The relationship bebween totql arsa of izvxd road and the concrntratnon of CO. 3. Thw repationship begwern total arfa oh pcved road and the concentration od Ox. 4. Rhf relationship bxtween total xrea kf pavgd road and the
been gradually shifted from coal and oil gas renewable energy 1967, which leads gases NO2 (De Gouw al., 2014; Higazy al., 2019; OECD, 2013). With 66% energy in Kitakyushu city is consumed by industrial activities and energy conversion is affordable to larger industrial firms, the emissions of NO2 and CO might be as firms It been reported that despite accounting for the largest proportion of energy consumption in Kitakyushu city, the sector keeps growing while air emissions from energy are still under control 2013). As such, the evidence toward EKC of and emissions the results of stringent pollution monitoring, controls and financial support of local government, (2) replacement of energy-efficient technologies, (3) economies scale effects, the energy conversion coal oil to natural renewable sources. However, our analysis also amount of falling dust particle and Ox, after initial decline, to rise when the industrial sector to a level of $9.32 million to $10.91 of shipment value per firm depends on the model of analysis. In 2013, the OECD that where a rising of large firms iron chemical, automobile etc. are to outsource their activities to smaller firms to whom enforcement and are more difficult to apply. This could essentially explain the Hence, in Kitakyushu city suggested to revise inspection with to small and medium order stay changing of industry. The problems with development. Besides the significant relationship firm-level industrial growth and both negative and positive correlations of road infrastructure with air pollution. On one hand, our shows a positive effect of road construction on alleviating the amount of dust and These findings can be explained by the fact as higher quality Fig. Illustrations of the relationship between the total area of road air pollutions. The relationship between area of paved and the amount dust. 2. relationship total road and the concentration of CO. The between total area of paved and of Ox. 4. The relationship between total area of paved road and the
 been gradually shifted from cOal and oil tO natuRal Gas AnD renEwabLe energy since 1967, wHIch lEads to lower emissions of GreenHoUSe gaSEs And NO2 (de Gouw eT Al., 2014; hIGazY eT aL., 2019; OEcD, 2013). wItH 66% of enErgY in KitaKyushu city Is cOnSumed by indusTRiAl activitiEs aNd energy convErsIon is mOrE afFOrdabLe tO largEr induSTrial fIrms, the emIsSIons of no2 and CO mIGHt Be reDuced as industrial FIrMS grow. It has been ReportEd THaT DEspIte Accounting FoR the lARgest prOPoRTIOn oF Energy consumpTion in KitakYUshU city, tHe IndUStrial SectoR kEEps Growing whilE air Emissions From enERgy geneRAtion arE still UndEr cOntrOL (OeCd, 2013). As SuCH, thE EvIdeNCe pOints towArD tHe EKC Of NO2 AND co emiSsiOns aRe the Results of (1) striNgeNt poLLutIon moNitorIng, cOnTrols And finAnciaL sUpport of local goVernMent, (2) replaCemEnT of EnErgy-eFFicienT teChnOlogies, (3) EconomiES of ScALE EfFects, and (4) the energy sOuRCE cOnversioN from cOAl AnD Oil to natUrAl gAs anD REnewaBle sOUrCes. HowevEr, our aNAlYsIs also sHoWs that ThE amOunT of faLLing Dust paRticle anD Ox, afTEr the initial deCLine, starts to rISe WHEn THe inDusTrial sector ExpaNDs to A levEL oF $9.32 miLLion tO $10.91 millIoN Of SHipment value per firm DePends oN the mOdel of analysiS. In 2013, the OECD REPOrt warneD thaT WhERe a rising numbeR of laRge firms in IRon steel, ChemiCal, and auTomobile sECTors, etc. aRe rEpoRteD to OUTsOurce their actIVItieS tO smalleR fiRms to whOm eNfoRceMenT aNd inspectIon are moRe DiFfIcUlt To appLY. This couLd EssEnTiaLly exPLain thE analYsis ReSuLT. HeNce, poliCY-mAKErs iN KItAkyuShu CiTy are SuggESteD to reviSe inspectIon REgulAtIoNs with rEgards to small AnD medium firMs In oRder to STAy abreasT of the changing dynamics oF The induStrY. The pRoblEms with inFraStructUre DEvelopMent. BeSides ThE siGNIficaNT ReLatIoNship betweEN FirM-leveL iNdusTrial grOwth and air pollutioN, We aLso found both nEgaTive AND pOsiTIvE CorReLAtiONS of road infrastrUcture deveLoPMeNt with air pOLluTiOn. On one Hand, our AnalySIs shows A positive Effect of rOaD conSTRucTion on alleViating tHe amount oF FalliNG dUst anD CO ConcenTrAtiOn. TheSe findINgs Can be ExplaiNeD by the Fact tHaT as higheR quality Fig. 3 IllustrationS of the RelatIonShip betweEn tHE toTal area of PaveD road and aiR poLluTions. 1. the RElatiOnshIP bEtwEEn totAl arEA of paved rOAd And THE aMount of fallING DusT. 2. The rElaTIonshiP betWeen total area of paVEd road and the coNcenTRAtiOn oF cO. 3. ThE rElationship betWeeN tOTAl area of PaVed road and tHe concenTrATion oF Ox. 4. The RelatiOnship bETWeEN total Area Of pAved road aNd tHe
 been gradually shifted fr om coal an d oil  to  na tu ralgasand renewablee nerg y since 1967, which le ads t ol ower em issio ns of g r ee n h ous ega ses  a n dNO2 ( DeGouw et  al., 2014 ; H ig azy et al.,2 01 9; OECD, 2 013 ). With 66%ofenergy  i n K i takyu shu  city  is co n sumedby indust ri a l acti v ities a n d  e nerg y conversion is m o re affordable tolarger  i n du s t ria l f irms, theem issio n s of NO 2  a n d COm ight be reduc ed as indus t ria l firm sgro w . It h as be en rep orted thatdesp ite accou ntingf or thel argestpropor tio n o f en e rg ycon su m pti o ninK ita kyushu c it y,  theindu s t r i al s ect or k eepsgrowing while  ai r em i ssi ons f rom e nerg ygener ationare s ti ll under contro l (O ECD, 2013 ).As  su ch , the eviden cepoi nts tow ard the EKC  o f N O2  and CO emissionsar e th e result s of ( 1 )st r ingent p ol lut ionm o nitor ing, co ntrols a nd fin a nc ia l suppo rt  of lo ca l g ove rnmen t , (2 ) repl acementof en e rgy-efficientt echnologies,( 3) e co n omie s o f scale eff ects ,  and  (4) th e e n ergysourc ec on v ersion from coal an doil to  natu ral gas and r enewable s o u r ces. How ever ,  o u r analysis als o sho ws that th e  amountof fa lling du st partic l e  and Ox,  af ter  th e i n i ti al decline, s t a rtsto  rise w hen  the in dus tri alsec to r expands  to a le ve lof  $ 9.3 2 mil l ion to $ 10 .91  m ill ion o f  shipm ent v alue  p er fir m depen d so n  the  m od el o f a na lysis . In 201 3, theOECD repo rtw arne dth at wher e a rising nu mb er of larg efir ms ini r on steel , chemical, and automob i le sect ors , etc . ar e reporte d t o outs our c e thei r acti vitie stos m aller f ir msto  whom enfo r c eme nt an dinsp ectionare more difficult toapply. This c oul d es s e nt ial l ye xpl ai n  th e analysis result . Hence, p ol i cy -makers in Kit ak yushu c ity are  sugg e sted to  revise i nspection  r egul a t ion s with reg ards tosmall and mediu m  f irmsinorderto  st ay ab reasto f t he ch anging  d ynamic s ofth e indust ry. The problems with i nfrast ructu redevelopme nt. Bes ides thesign ificant re lat ion shipbet w een f irm- l ev eli ndust rial growth an d  a irp o ll ution, we a l s o  fo und b oth negati ve a nd positive corre l ations of road  inf r a str uct u re d ev elopment withair  p o l lution.On  one hand,our anal ys i s sho ws a p ositiv e effec t of road c onst ruc tion on a lle vi a ting th eam o unt of  fal li ng dus t andC O co n c entration. These  find i n gs ca n  be  expl ai ned byt he f act that a s higher qu alityFig.  3 Il lustrat io ns ofthe  r elationshi p  betweenthe t otal ar ea  ofpav ed roa d an d air p ollu ti ons . 1. Ther e la t io ns h ipbetw een t ot al a rea of pa v ed roadand the amo un t o f fallin g  d u s t. 2. Therel ation s h ip between tota l  a r ea of  paved  roadand the con ce ntratio n o f CO. 3. Th e relatio n shi pbetw een tota larea  o f p av ed road and the  concent ration o f Ox. 4.  Th e  rel a tionsh ip  between tot al ar ea of pave d roa d and t h e
 been_gradually shifted_from coal and oil_to natural_gas_and renewable_energy_since 1967, which_leads to lower_emissions of greenhouse gases_and NO2 (De_Gouw_et al., 2014; Higazy et al., 2019; OECD, 2013). With 66% of energy in_Kitakyushu_city is_consumed_by_industrial activities and energy conversion_is more affordable to larger_industrial firms,_the emissions of NO2 and CO might be_reduced_as industrial firms_grow. It has been reported that despite accounting for_the largest proportion of energy consumption_in Kitakyushu city,_the_industrial_sector keeps growing while_air emissions from energy generation are_still under control (OECD, 2013). As_such, the evidence points toward the EKC_of NO2 and CO emissions are_the results of (1) stringent_pollution monitoring,_controls and financial support of_local government, (2)_replacement of_energy-efficient technologies, (3)_economies of scale effects, and (4)_the energy source_conversion from coal and oil to_natural_gas and renewable_sources._However,_our analysis_also shows that_the_amount of_falling_dust particle and Ox, after the_initial_decline, starts to rise when the industrial_sector expands to a_level_of $9.32 million to_$10.91 million of shipment value_per firm depends on the model_of analysis._In 2013,_the OECD report warned that where a rising number of large_firms in iron steel, chemical, and_automobile sectors, etc. are_reported to_outsource_their activities to_smaller_firms to_whom enforcement and inspection are more difficult_to apply._This could essentially explain the analysis_result. Hence, policy-makers in_Kitakyushu_city are suggested to revise inspection_regulations with regards to small and_medium firms in order to_stay_abreast_of the changing dynamics of_the industry. The problems with infrastructure_development. Besides the_significant relationship between firm-level industrial growth and_air_pollution, we also found both negative_and_positive correlations of road infrastructure development_with_air_pollution. On one hand, our_analysis shows a positive effect of_road construction on alleviating the amount of falling dust_and CO concentration._These findings can be explained_by_the_fact that as higher quality Fig. 3 Illustrations of the_relationship between_the total area_of paved road and air pollutions. 1. The relationship between_total area of paved road and the_amount of falling dust. 2. The relationship between total area of_paved road and the concentration of CO. 3._The relationship between total area of paved_road and the concentration_of_Ox. 4. The relationship between total area_of_paved_road_and the