{"abstract":"Based on its review of the air quality criteria and the national ambient air quality standards (NAAQS) for carbon monoxide (CO), EPA is proposing to retain the current standards. EPA is also proposing changes to the ambient air monitoring requirements for CO including those related to network design.","action":"Proposed rule.","agencies":[{"raw_name":"ENVIRONMENTAL PROTECTION AGENCY","name":"Environmental Protection Agency","id":145,"url":"https://www.federalregister.gov/agencies/environmental-protection-agency","json_url":"https://www.federalregister.gov/api/v1/agencies/145","parent_id":null,"slug":"environmental-protection-agency"}],"body_html_url":"https://www.federalregister.gov/documents/full_text/html/2011/02/11/2011-2404.html","cfr_references":[{"chapter":null,"citation_url":null,"part":50,"title":40},{"chapter":null,"citation_url":null,"part":53,"title":40},{"chapter":null,"citation_url":null,"part":58,"title":40}],"citation":"76 FR 8158","comment_url":null,"comments_close_on":"2011-04-12","correction_of":null,"corrections":[],"dates":"Comments must be received on or before April 12, 2011.","disposition_notes":null,"docket_ids":["EPA-HQ-OAR-2008-0015","FRL-9261-4","2060-AI43"],"dockets":[],"document_number":"2011-2404","effective_on":null,"end_page":8220,"executive_order_notes":null,"executive_order_number":null,"full_text_xml_url":"https://www.federalregister.gov/documents/full_text/xml/2011/02/11/2011-2404.xml","html_url":"https://www.federalregister.gov/documents/2011/02/11/2011-2404/national-ambient-air-quality-standards-for-carbon-monoxide","images":{"EP11FE11.146":{"large":"https://img.federalregister.gov/EP11FE11.146/EP11FE11.146_large.png","medium":"https://img.federalregister.gov/EP11FE11.146/EP11FE11.146_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.146/EP11FE11.146_original_size.png"},"EP11FE11.145":{"large":"https://img.federalregister.gov/EP11FE11.145/EP11FE11.145_large.png","medium":"https://img.federalregister.gov/EP11FE11.145/EP11FE11.145_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.145/EP11FE11.145_original_size.png"},"EP11FE11.144":{"large":"https://img.federalregister.gov/EP11FE11.144/EP11FE11.144_large.png","medium":"https://img.federalregister.gov/EP11FE11.144/EP11FE11.144_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.144/EP11FE11.144_original_size.png"},"EP11FE11.155":{"large":"https://img.federalregister.gov/EP11FE11.155/EP11FE11.155_large.png","medium":"https://img.federalregister.gov/EP11FE11.155/EP11FE11.155_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.155/EP11FE11.155_original_size.png"},"EP11FE11.143":{"large":"https://img.federalregister.gov/EP11FE11.143/EP11FE11.143_large.png","medium":"https://img.federalregister.gov/EP11FE11.143/EP11FE11.143_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.143/EP11FE11.143_original_size.png"},"EP11FE11.154":{"large":"https://img.federalregister.gov/EP11FE11.154/EP11FE11.154_large.png","medium":"https://img.federalregister.gov/EP11FE11.154/EP11FE11.154_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.154/EP11FE11.154_original_size.png"},"EP11FE11.142":{"large":"https://img.federalregister.gov/EP11FE11.142/EP11FE11.142_large.png","medium":"https://img.federalregister.gov/EP11FE11.142/EP11FE11.142_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.142/EP11FE11.142_original_size.png"},"EP11FE11.153":{"large":"https://img.federalregister.gov/EP11FE11.153/EP11FE11.153_large.png","medium":"https://img.federalregister.gov/EP11FE11.153/EP11FE11.153_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.153/EP11FE11.153_original_size.png"},"EP11FE11.141":{"large":"https://img.federalregister.gov/EP11FE11.141/EP11FE11.141_large.png","medium":"https://img.federalregister.gov/EP11FE11.141/EP11FE11.141_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.141/EP11FE11.141_original_size.png"},"EP11FE11.152":{"large":"https://img.federalregister.gov/EP11FE11.152/EP11FE11.152_large.png","medium":"https://img.federalregister.gov/EP11FE11.152/EP11FE11.152_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.152/EP11FE11.152_original_size.png"},"EP11FE11.140":{"large":"https://img.federalregister.gov/EP11FE11.140/EP11FE11.140_large.png","medium":"https://img.federalregister.gov/EP11FE11.140/EP11FE11.140_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.140/EP11FE11.140_original_size.png"},"EP11FE11.151":{"large":"https://img.federalregister.gov/EP11FE11.151/EP11FE11.151_large.png","medium":"https://img.federalregister.gov/EP11FE11.151/EP11FE11.151_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.151/EP11FE11.151_original_size.png"},"EP11FE11.150":{"large":"https://img.federalregister.gov/EP11FE11.150/EP11FE11.150_large.png","medium":"https://img.federalregister.gov/EP11FE11.150/EP11FE11.150_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.150/EP11FE11.150_original_size.png"},"EP11FE11.139":{"large":"https://img.federalregister.gov/EP11FE11.139/EP11FE11.139_large.png","medium":"https://img.federalregister.gov/EP11FE11.139/EP11FE11.139_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.139/EP11FE11.139_original_size.png"},"EP11FE11.138":{"large":"https://img.federalregister.gov/EP11FE11.138/EP11FE11.138_large.png","medium":"https://img.federalregister.gov/EP11FE11.138/EP11FE11.138_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.138/EP11FE11.138_original_size.png"},"EP11FE11.149":{"large":"https://img.federalregister.gov/EP11FE11.149/EP11FE11.149_large.png","medium":"https://img.federalregister.gov/EP11FE11.149/EP11FE11.149_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.149/EP11FE11.149_original_size.png"},"EP11FE11.148":{"large":"https://img.federalregister.gov/EP11FE11.148/EP11FE11.148_large.png","medium":"https://img.federalregister.gov/EP11FE11.148/EP11FE11.148_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.148/EP11FE11.148_original_size.png"},"EP11FE11.147":{"large":"https://img.federalregister.gov/EP11FE11.147/EP11FE11.147_large.png","medium":"https://img.federalregister.gov/EP11FE11.147/EP11FE11.147_medium.png","original_size":"https://img.federalregister.gov/EP11FE11.147/EP11FE11.147_original_size.png"}},"images_metadata":{"EP11FE11.146":{"large":{"identifier":"EP11FE11.146","content_type":"image/png","size":1321,"width":142,"sha":"9c204b5dbf96e13fb274ddaa344e84cf","url":"https://img.federalregister.gov/EP11FE11.146/EP11FE11.146_large.png","height":66},"medium":{"identifier":"EP11FE11.146","content_type":"image/png","size":531,"width":67,"sha":"3656d11795b382215a60476c8c2fe9fe","url":"https://img.federalregister.gov/EP11FE11.146/EP11FE11.146_medium.png","height":31},"original_size":{"identifier":"EP11FE11.146","content_type":"image/png","size":1945,"width":506,"sha":"f1bb0f0f24491ced1fb38e976febdcfe","url":"https://img.federalregister.gov/EP11FE11.146/EP11FE11.146_original_size.png","height":235}},"EP11FE11.145":{"large":{"identifier":"EP11FE11.145","content_type":"image/png","size":2013,"width":255,"sha":"339160ce54ae857419ae94fa13188013","url":"https://img.federalregister.gov/EP11FE11.145/EP11FE11.145_large.png","height":68},"medium":{"identifier":"EP11FE11.145","content_type":"image/png","size":791,"width":120,"sha":"176e044a724bce44077b7a25b384603c","url":"https://img.federalregister.gov/EP11FE11.145/EP11FE11.145_medium.png","height":32},"original_size":{"identifier":"EP11FE11.145","content_type":"image/png","size":3121,"width":916,"sha":"b910eb6c2df3e61b05a55c2aa49ef77e","url":"https://img.federalregister.gov/EP11FE11.145/EP11FE11.145_original_size.png","height":244}},"EP11FE11.144":{"large":{"identifier":"EP11FE11.144","content_type":"image/png","size":2003,"width":256,"sha":"d3cec6fa8889e47b6632f697b4ee61dd","url":"https://img.federalregister.gov/EP11FE11.144/EP11FE11.144_large.png","height":65},"medium":{"identifier":"EP11FE11.144","content_type":"image/png","size":773,"width":120,"sha":"7e50c0204b6dd74050abde5b45c7d951","url":"https://img.federalregister.gov/EP11FE11.144/EP11FE11.144_medium.png","height":31},"original_size":{"identifier":"EP11FE11.144","content_type":"image/png","size":3023,"width":908,"sha":"0d72fe4057ca09397815d9549a90e1c9","url":"https://img.federalregister.gov/EP11FE11.144/EP11FE11.144_original_size.png","height":232}},"EP11FE11.155":{"large":{"identifier":"EP11FE11.155","content_type":"image/png","size":3034,"width":373,"sha":"3d887ce7a08f26e6b42d51b23ac22a4e","url":"https://img.federalregister.gov/EP11FE11.155/EP11FE11.155_large.png","height":69},"medium":{"identifier":"EP11FE11.155","content_type":"image/png","size":1133,"width":176,"sha":"cf351cc1b52e1a87793cfbbbc4b64d19","url":"https://img.federalregister.gov/EP11FE11.155/EP11FE11.155_medium.png","height":33},"original_size":{"identifier":"EP11FE11.155","content_type":"image/png","size":4626,"width":1325,"sha":"e97e65df21ac0adcab3089fccbcecfc9","url":"https://img.federalregister.gov/EP11FE11.155/EP11FE11.155_original_size.png","height":246}},"EP11FE11.143":{"large":{"identifier":"EP11FE11.143","content_type":"image/png","size":75286,"width":823,"sha":"70cb96727f3750effbc184de514dbc85","url":"https://img.federalregister.gov/EP11FE11.143/EP11FE11.143_large.png","height":1125},"medium":{"identifier":"EP11FE11.143","content_type":"image/png","size":27266,"width":397,"sha":"69bd65246aa21531f4f63be1c24455b1","url":"https://img.federalregister.gov/EP11FE11.143/EP11FE11.143_medium.png","height":543},"original_size":{"identifier":"EP11FE11.143","content_type":"image/png","size":191088,"width":2996,"sha":"45ee10c533e80ef011f7e7a0b6ab207f","url":"https://img.federalregister.gov/EP11FE11.143/EP11FE11.143_original_size.png","height":4096}},"EP11FE11.154":{"large":{"identifier":"EP11FE11.154","content_type":"image/png","size":2909,"width":352,"sha":"b9fbf5082511c3c96cb2cd92906fd3d2","url":"https://img.federalregister.gov/EP11FE11.154/EP11FE11.154_large.png","height":66},"medium":{"identifier":"EP11FE11.154","content_type":"image/png","size":1085,"width":166,"sha":"fce3b45e0411c0d479b796510059a424","url":"https://img.federalregister.gov/EP11FE11.154/EP11FE11.154_medium.png","height":31},"original_size":{"identifier":"EP11FE11.154","content_type":"image/png","size":4649,"width":1253,"sha":"c2589e9ed69cef1d379d595c68025a5d","url":"https://img.federalregister.gov/EP11FE11.154/EP11FE11.154_original_size.png","height":234}},"EP11FE11.142":{"large":{"identifier":"EP11FE11.142","content_type":"image/png","size":63102,"width":823,"sha":"3595fd0b863142e8de0420767065de72","url":"https://img.federalregister.gov/EP11FE11.142/EP11FE11.142_large.png","height":1045},"medium":{"identifier":"EP11FE11.142","content_type":"image/png","size":37221,"width":574,"sha":"d19c016fb68f3bebd4c765f692ecb3f4","url":"https://img.federalregister.gov/EP11FE11.142/EP11FE11.142_medium.png","height":729},"original_size":{"identifier":"EP11FE11.142","content_type":"image/png","size":149522,"width":4333,"sha":"25ad7c8d581a4e318fca5c9b425818bf","url":"https://img.federalregister.gov/EP11FE11.142/EP11FE11.142_original_size.png","height":5503}},"EP11FE11.153":{"large":{"identifier":"EP11FE11.153","content_type":"image/png","size":60748,"width":823,"sha":"7a3d1bb733fd6718b1664b06dd4e5e55","url":"https://img.federalregister.gov/EP11FE11.153/EP11FE11.153_large.png","height":856},"medium":{"identifier":"EP11FE11.153","content_type":"image/png","size":29884,"width":528,"sha":"5e8c8d29269bc92783f65b86ff617796","url":"https://img.federalregister.gov/EP11FE11.153/EP11FE11.153_medium.png","height":549},"original_size":{"identifier":"EP11FE11.153","content_type":"image/png","size":95337,"width":3985,"sha":"d26661939fd132342b05449842fef6a0","url":"https://img.federalregister.gov/EP11FE11.153/EP11FE11.153_original_size.png","height":4144}},"EP11FE11.141":{"large":{"identifier":"EP11FE11.141","content_type":"image/png","size":98010,"width":823,"sha":"35d1f3a5aed31c831cb5acf52a253540","url":"https://img.federalregister.gov/EP11FE11.141/EP11FE11.141_large.png","height":1168},"medium":{"identifier":"EP11FE11.141","content_type":"image/png","size":47174,"width":513,"sha":"8fe3c02c325296ee9146d650c0c1f8c4","url":"https://img.federalregister.gov/EP11FE11.141/EP11FE11.141_medium.png","height":728},"original_size":{"identifier":"EP11FE11.141","content_type":"image/png","size":176967,"width":3878,"sha":"2af4db779c949466c675a7a6311f7a6a","url":"https://img.federalregister.gov/EP11FE11.141/EP11FE11.141_original_size.png","height":5503}},"EP11FE11.152":{"large":{"identifier":"EP11FE11.152","content_type":"image/png","size":85207,"width":823,"sha":"40e289b0e4dfab145f06fc0483d015d9","url":"https://img.federalregister.gov/EP11FE11.152/EP11FE11.152_large.png","height":1299},"medium":{"identifier":"EP11FE11.152","content_type":"image/png","size":36828,"width":461,"sha":"e3e9044b9911d2d86fff0f79018d46ae","url":"https://img.federalregister.gov/EP11FE11.152/EP11FE11.152_medium.png","height":728},"original_size":{"identifier":"EP11FE11.152","content_type":"image/png","size":224956,"width":3484,"sha":"614aa7b223765c736544d0f89613daef","url":"https://img.federalregister.gov/EP11FE11.152/EP11FE11.152_original_size.png","height":5502}},"EP11FE11.140":{"large":{"identifier":"EP11FE11.140","content_type":"image/png","size":3872,"width":337,"sha":"1c3b42f11381e7e9028996c2c1b5b9b2","url":"https://img.federalregister.gov/EP11FE11.140/EP11FE11.140_large.png","height":96},"medium":{"identifier":"EP11FE11.140","content_type":"image/png","size":1405,"width":158,"sha":"03e7ba8e919fe7a1f4ae5efa3749b09f","url":"https://img.federalregister.gov/EP11FE11.140/EP11FE11.140_medium.png","height":45},"original_size":{"identifier":"EP11FE11.140","content_type":"image/png","size":5192,"width":1208,"sha":"f5ebb095f9b05d3ef0357f759fa075c4","url":"https://img.federalregister.gov/EP11FE11.140/EP11FE11.140_original_size.png","height":344}},"EP11FE11.151":{"large":{"identifier":"EP11FE11.151","content_type":"image/png","size":77032,"width":823,"sha":"77d7ed86a16a0126380d31d981cca5f9","url":"https://img.federalregister.gov/EP11FE11.151/EP11FE11.151_large.png","height":1201},"medium":{"identifier":"EP11FE11.151","content_type":"image/png","size":39868,"width":490,"sha":"db7ec519581c71365dcd9fcdf8be791b","url":"https://img.federalregister.gov/EP11FE11.151/EP11FE11.151_medium.png","height":715},"original_size":{"identifier":"EP11FE11.151","content_type":"image/png","size":244999,"width":3701,"sha":"d9d3c1dda865efcb853509855b5de899","url":"https://img.federalregister.gov/EP11FE11.151/EP11FE11.151_original_size.png","height":5402}},"EP11FE11.150":{"large":{"identifier":"EP11FE11.150","content_type":"image/png","size":68772,"width":823,"sha":"3b8023dc72ac98f545f6700316927820","url":"https://img.federalregister.gov/EP11FE11.150/EP11FE11.150_large.png","height":1117},"medium":{"identifier":"EP11FE11.150","content_type":"image/png","size":34404,"width":503,"sha":"a908503a10b1f463533b7558bea8c5ce","url":"https://img.federalregister.gov/EP11FE11.150/EP11FE11.150_medium.png","height":683},"original_size":{"identifier":"EP11FE11.150","content_type":"image/png","size":102819,"width":3798,"sha":"52765e8b464199b02f1bff7e2a336cce","url":"https://img.federalregister.gov/EP11FE11.150/EP11FE11.150_original_size.png","height":5157}},"EP11FE11.139":{"large":{"identifier":"EP11FE11.139","content_type":"image/png","size":40099,"width":790,"sha":"50afbfd1ae1bd7022d192e45b5728a79","url":"https://img.federalregister.gov/EP11FE11.139/EP11FE11.139_large.png","height":1298},"medium":{"identifier":"EP11FE11.139","content_type":"image/png","size":14821,"width":372,"sha":"afd61237856f1b5e30dd47cdfb81a475","url":"https://img.federalregister.gov/EP11FE11.139/EP11FE11.139_medium.png","height":611},"original_size":{"identifier":"EP11FE11.139","content_type":"image/png","size":52474,"width":2812,"sha":"a366f139d7829fbffffe62c8d4f33ffc","url":"https://img.federalregister.gov/EP11FE11.139/EP11FE11.139_original_size.png","height":4620}},"EP11FE11.138":{"large":{"identifier":"EP11FE11.138","content_type":"image/png","size":38770,"width":823,"sha":"3ad80de30953c89b6281e924467df5a5","url":"https://img.federalregister.gov/EP11FE11.138/EP11FE11.138_large.png","height":1237},"medium":{"identifier":"EP11FE11.138","content_type":"image/png","size":14335,"width":397,"sha":"9f297d81497200fa4be497009c02e85f","url":"https://img.federalregister.gov/EP11FE11.138/EP11FE11.138_medium.png","height":597},"original_size":{"identifier":"EP11FE11.138","content_type":"image/png","size":49051,"width":2998,"sha":"66754d6f1e670e8cf0085a484d16c171","url":"https://img.federalregister.gov/EP11FE11.138/EP11FE11.138_original_size.png","height":4506}},"EP11FE11.149":{"large":{"identifier":"EP11FE11.149","content_type":"image/png","size":41147,"width":823,"sha":"6e56c58239fb7e966d162b247a0cfa6c","url":"https://img.federalregister.gov/EP11FE11.149/EP11FE11.149_large.png","height":1144},"medium":{"identifier":"EP11FE11.149","content_type":"image/png","size":20072,"width":489,"sha":"87f2b1d5b53a2754872ecc04f2ac16f6","url":"https://img.federalregister.gov/EP11FE11.149/EP11FE11.149_medium.png","height":680},"original_size":{"identifier":"EP11FE11.149","content_type":"image/png","size":57757,"width":3690,"sha":"7abab3e5be7f40428ddf9430ac5ab80a","url":"https://img.federalregister.gov/EP11FE11.149/EP11FE11.149_original_size.png","height":5132}},"EP11FE11.148":{"large":{"identifier":"EP11FE11.148","content_type":"image/png","size":5048,"width":472,"sha":"0bbfc3ba865ff35e85cd7a970ac87272","url":"https://img.federalregister.gov/EP11FE11.148/EP11FE11.148_large.png","height":96},"medium":{"identifier":"EP11FE11.148","content_type":"image/png","size":1769,"width":221,"sha":"96e035b578b9d3442e5259479499c21a","url":"https://img.federalregister.gov/EP11FE11.148/EP11FE11.148_medium.png","height":45},"original_size":{"identifier":"EP11FE11.148","content_type":"image/png","size":6857,"width":1690,"sha":"8156c5aa6f5b79a7f39ae2dc6cdc9286","url":"https://img.federalregister.gov/EP11FE11.148/EP11FE11.148_original_size.png","height":344}},"EP11FE11.147":{"large":{"identifier":"EP11FE11.147","content_type":"image/png","size":4697,"width":472,"sha":"bf8205ab42df78ee670e5859e397c360","url":"https://img.federalregister.gov/EP11FE11.147/EP11FE11.147_large.png","height":96},"medium":{"identifier":"EP11FE11.147","content_type":"image/png","size":1819,"width":221,"sha":"8ffeb11a9e49784dbf052e7f2b4e323d","url":"https://img.federalregister.gov/EP11FE11.147/EP11FE11.147_medium.png","height":45},"original_size":{"identifier":"EP11FE11.147","content_type":"image/png","size":6811,"width":1691,"sha":"d13932548178c64c3505f2e159e6c365","url":"https://img.federalregister.gov/EP11FE11.147/EP11FE11.147_original_size.png","height":344}}},"json_url":"https://www.federalregister.gov/api/v1/documents/2011-2404?publication_date=2011-02-11","mods_url":"https://www.govinfo.gov/metadata/granule/FR-2011-02-11/2011-2404/mods.xml","not_received_for_publication":null,"page_length":63,"page_views":{"count":1024,"last_updated":"2026-09-20 18:15:07 -0400"},"pdf_url":"https://www.govinfo.gov/content/pkg/FR-2011-02-11/pdf/2011-2404.pdf","presidential_document_number":null,"proclamation_number":null,"public_inspection_pdf_url":null,"publication_date":"2011-02-11","raw_text_url":"https://www.federalregister.gov/documents/full_text/text/2011/02/11/2011-2404.txt","regulation_id_number_info":{},"regulation_id_numbers":[],"regulations_dot_gov_info":{"checked_regulationsdotgov_at":"2011-03-03T08:35:14Z"},"regulations_dot_gov_url":null,"significant":null,"signing_date":null,"start_page":8158,"subtype":null,"title":"National Ambient Air Quality Standards for Carbon Monoxide","toc_doc":"National Ambient Air Quality Standards for Carbon Monoxide","toc_subject":null,"topics":["Administrative practice and procedure","Air pollution control","Carbon monoxide","Environmental protection","Intergovernmental relations","Lead","Nitrogen dioxide","Ozone","Particulate matter","Reporting and recordkeeping requirements","Sulfur oxides"],"type":"Proposed Rule","volume":76}