[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-seo-269348-105":3,"detail-sidebar-cat-0-en-105":81,"doc-detail-269348-en":131},{"code":4,"msg":5,"data":6},0,"ok",{"site_id":7,"language":8,"slug":9,"title":10,"keywords":11,"description":12,"schema_data":13,"social_meta":74,"head_meta":76,"extra_data":78,"updated_unix":80},105,"en","do-smog-checks-affect-smog-emissions-inspections-station-quality-and-local-air-pollution","Do Smog Checks Affect Smog? Emissions Inspections, Station Quality and Local Air Pollution","","Personal automobile emissions drive substantial urban air pollution, and many U.S. states use mandated emissions inspections and repairs to control vehicle tailpipe output. Yet evidence linking these inspection and maintenance requirements to local air pollution levels remains limited. Using individual-level data from California’s inspection program, the study estimates inspections’ contemporaneous effects via within-county day-to-day variation in recertifications after failed tests, finding meaningful reductions for older vehicles and mixed station-quality impacts.",{"@graph":14,"@context":73},[15,34,56],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/document/","Document",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/document/research-report/","Research & Report",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/document/do-smog-checks-affect-smog-emissions-inspections-station-quality-and-local-air-pollution/269348/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/do-smog-checks-affect-smog-emissions-inspections-station-quality-and-local-air-pollution/269348.png","ImageObject",300,407,{"name":42,"@type":43},"Genevieve","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/pdf","2026-10-29","2026-09-15",true,{"@type":52,"interactionType":53,"userInteractionCount":55},"InteractionCounter",{"@type":54},"ViewAction",16,{"@type":57,"mainEntity":58},"FAQPage",[59,65,69],{"name":60,"@type":61,"acceptedAnswer":62},"What is the main question of the study?","Question",{"text":63,"@type":64},"The study asks whether mandated emissions inspections and repairs reduce local air pollution levels in practice, rather than only in testing environments.","Answer",{"name":66,"@type":61,"acceptedAnswer":67},"How does the paper identify the effect of inspections?",{"text":68,"@type":64},"It leverages California data and uses within-county day-to-day variation in the number of vehicles recertified after failing an initial inspection to isolate inspections’ contemporaneous effects.",{"name":70,"@type":61,"acceptedAnswer":71},"What do the results suggest for older versus newer vehicles?",{"text":72,"@type":64},"Additional re-inspections of older (pre-1985) vehicles reduce local carbon monoxide, nitrogen oxide, and particulate matter, while re-inspections of newer vehicles show no economically significant air-pollution effect.","https://schema.org",{"og:url":32,"og:type":75,"og:title":10,"og:site_name":45,"og:description":12},"article",{"robots":77,"canonical":32},"index,follow",{"doc_id":79,"site_id":7},269348,1789450746,{"code":4,"msg":82,"data":83},"success",[84,88,92,96,101,106,111,115,120,123,127],{"id":22,"doc_module":4,"doc_module_name":25,"category_name":85,"show_sort_weight":86,"slug":87},"Story & Novel",90,"story-novel",{"id":26,"doc_module":4,"doc_module_name":25,"category_name":89,"show_sort_weight":90,"slug":91},"Literature",80,"literature",{"id":33,"doc_module":4,"doc_module_name":25,"category_name":93,"show_sort_weight":94,"slug":95},"Exam",70,"exam",{"id":97,"doc_module":4,"doc_module_name":25,"category_name":98,"show_sort_weight":99,"slug":100},5,"Comic",60,"comic",{"id":102,"doc_module":4,"doc_module_name":25,"category_name":103,"show_sort_weight":104,"slug":105},6,"Technology",50,"technology",{"id":107,"doc_module":4,"doc_module_name":25,"category_name":108,"show_sort_weight":109,"slug":110},7,"Healthcare",40,"healthcare",{"id":112,"doc_module":4,"doc_module_name":25,"category_name":29,"show_sort_weight":113,"slug":114},8,30,"research-report",{"id":116,"doc_module":4,"doc_module_name":25,"category_name":117,"show_sort_weight":118,"slug":119},9,"Religion & Spirituality",20,"religion-spirituality",{"id":118,"doc_module":4,"doc_module_name":25,"category_name":121,"show_sort_weight":118,"slug":122},"World Cup","world-cup",{"id":124,"doc_module":4,"doc_module_name":25,"category_name":125,"show_sort_weight":124,"slug":126},10,"Lifestyle","lifestyle",{"id":128,"doc_module":4,"doc_module_name":25,"category_name":129,"show_sort_weight":97,"slug":130},19,"General","general",{"code":4,"msg":82,"data":132},{"doc_id":79,"user_id":133,"nickname":42,"user_avatar":134,"doc_module":4,"category_id":112,"category_name":29,"doc_title":10,"doc_description":12,"doc_content":135,"file_id":136,"file_url":137,"file_type":138,"file_size":139,"view_count":55,"is_deleted":4,"is_public":22,"is_downloadable":22,"audit_status":22,"page_count":140,"language":141,"language_code":8,"site_id":7,"html_lang":8,"table_of_contents":142,"faqs":143,"seo_title":144,"seo_description":12,"update_tm":80,"read_time":145,"preview_page_count":4},1374391974585,"https://ap-avatar.wpscdn.com/davatar_276721f389ce27ea32af1340a28f341c","Do Smog Checks A􀀋ect Smog? Emissions Inspections, Station Quality and Local Air Pollution  \nNicholas J. Sanders and Ryan Sandler 􀀃  \nNovember 13, 2015  \nAbstract  \nPersonal automobile emissions are a major source of urban air pollution. Many  \nU.S. states control emissions through mandated vehicle inspections and repairs.  \nBut there is little empirical evidence directly linking mandated inspections, maintenance, and local air pollution levels. Using individual-level data from 1998{2012 from California's inspection program, we estimate the contemporaneous e􀀋ect of inspections on local air quality by exploiting day-to-day, within-county variation in the number of vehicles nominally repaired and recerti􀀌ed after failing an initial inspection. Additional re-inspections of pre-1985 model year vehicles reduce local carbon monoxide, nitrogen oxide, and particulate matter levels, while re-inspections of newer vehicles with more modern engine technology have no economically signi􀀌cant e􀀋ect on air pollution. This suggests emissions inspections become less e􀀋ective at reducing local air pollution as more high-polluting vehicles from the 1970s and 1980s leave the road. We also estimate the importance of station quality, using a metric devised for California's new STAR certi􀀌cation program. We show re-inspections of older vehicles conducted by low quality inspection stations do not change air pollution, while inspections at high quality stations have a moderate e􀀋ect on pollution concentrations. We 􀀌nd little e􀀋ect on ambient ozone levels, regardless of station quality or vehicle age.  \n􀀃 Sanders: Cornell University, [njsanders@cornell.edu](njsanders@cornell.edu). Sandler: Federal Trade Commission, rsan[dler@ftc.gov. We](dler@ftc.gov. We) are grateful to Dan Hosken, Mark Jacobsen, Thomas Koch, Devesh Raval, Joseph Shapiro and participants in the Economics Brownbag at the Federal Trade Commission for helpful comments and suggestions. Any opinions in this paper are those of the authors and do not necessarily re􀀍ect those of the Federal Trade Commission  \n1 Introduction  \nAutomobile pollution has substantial impacts on health, and regulating ambient air pollution from automobile tra􀀎c is a public concern both in the United States and abroad.1 Despite regulatory advancements and improvements in engine technology, motor vehicles remain responsible for 75% of carbon monoxide (CO) emissions in the United States, andover 50% of nitrogen oxide (NOx ) emissions.2 Governments in both developed and developing countries have tried a number of policies to reduce pollution from personal automobiles. Improving fuel standards can decrease emissions per mile driven, but such programs disproportionally impact low-income households and decrease average road safety (Jacobsen, 2013a,b) . Driving restriction programs have varied success rates when it comes to actually reducing local pollution (Davis, 2008; Wol􀀋, 2014) . Scrappage programs, often referred to as \\Cash for Clunkers,\" can directly remove the dirtiest vehicles from the road, but recent work shows that such programs have substantial problems with adverse selection and may only slightly shift forward the timing of vehicle replacement (Sandler, 2012; Mian and Su􀀌, 2012; Li et al., 2013; Hoekstra et al., 2014) . Inspection and maintenance programs (I/M), the focus of this paper, attempt to limit tailpipe emissions through regular inspections and repairs, without changing driving behavior or 􀀍eet composition. Such programs are costly both to governments and individuals (Ando et al., 2000), are subject to potential fraud (Oliva, 2015), and although mandated repairs of high-emitting vehicles often show reduced tailpipe emissions in a testing environment, there exists no large-scale analysis of how I/M programs a􀀋ect local air pollution. Understanding the e􀀋ectiveness of I/M in practice is especially important in light of the recent allegations of cheating onemissions tests involving Volkswagen diesel vehi","cbCaihIOBDvXquX2","https://ap.wps.com/l/cbCaihIOBDvXquX2","pdf",688715,43,"English","# Introduction\n## Emissions inspections and local air pollution\n## Policy context and motivation\n## Identification strategy","[{\"question\":\"What is the main question of the study?\",\"answer\":\"The study asks whether mandated emissions inspections and repairs reduce local air pollution levels in practice, rather than only in testing environments.\"},{\"question\":\"How does the paper identify the effect of inspections?\",\"answer\":\"It leverages California data and uses within-county day-to-day variation in the number of vehicles recertified after failing an initial inspection to isolate inspections’ contemporaneous effects.\"},{\"question\":\"What do the results suggest for older versus newer vehicles?\",\"answer\":\"Additional re-inspections of older (pre-1985) vehicles reduce local carbon monoxide, nitrogen oxide, and particulate matter, while re-inspections of newer vehicles show no economically significant air-pollution effect.\"}]","Do Smog Checks Affect Smog? Emissions Inspections, Station Quality and Local Air Pollution | PDF",108]