Editing Carbon monoxide (section)

== Pollution and health effects ==

=== Urban pollution ===
Carbon monoxide is a temporary atmospheric pollutant in some urban areas, chiefly from the exhaust of [[internal combustion engine]]s (including vehicles, portable and back-up generators, lawnmowers, power washers, etc.), but also from incomplete combustion of various other fuels (including wood, coal, charcoal, oil, paraffin, propane, natural gas, and trash).

Large CO pollution events can be observed from space over cities.<ref>{{Cite journal|last1=Pommier|first1=M.|last2=McLinden|first2=C. A.|last3=Deeter|first3=M.|year=2013|title=Relative changes in CO emissions over megacities based on observations from space|url=https://hal.archives-ouvertes.fr/hal-00844309/document|journal=Geophysical Research Letters|volume=40|issue=14|pages=3766|bibcode=2013GeoRL..40.3766P|doi=10.1002/grl.50704|doi-access=free}}</ref>

==== Role in ground level ozone formation ====
{{Main|Ground level ozone}}

Carbon monoxide is, along with [[aldehyde]]s, part of the series of cycles of chemical reactions that form [[photochemical smog]]. It reacts with hydroxyl radical (<sup>•</sup>OH) to produce a radical intermediate <sup>•</sup>HOCO, which rapidly transfers its radical hydrogen to {{chem2|O2}} to form [[peroxy]] radical ({{chem2|HO2}}<sup>•</sup>) and carbon dioxide ({{CO2}}).<ref>{{Cite journal|author1=Reeves, Claire E.|author2=Penkett, Stuart A.|author3=Bauguitte, Stephane|author4=Law, Kathy S.|author5=Evans, Mathew J.|author6=Bandy, Brian J.|author7=Monks, Paul S.|author8=Edwards, Gavin D.|author9=Phillips, Gavin|author10=Barjat, Hannah|author11=Kent, Joss|year=2002|title=Potential for photochemical ozone formation in the troposphere over the North Atlantic as derived from aircraft observationsduring ACSOE|url=http://juser.fz-juelich.de/record/34366|journal=Journal of Geophysical Research|volume=107|issue=D23|pages=4707|bibcode=2002JGRD..107.4707R|doi=10.1029/2002JD002415|doi-access=free|author14=Kley, Dieter|author13=Schmitgen, Sandra|author12=Dewey, Ken}}</ref> Peroxy radical subsequently reacts with [[nitrogen oxide]] (NO) to form [[nitrogen dioxide]] ({{chem2|NO2}}) and hydroxyl radical. {{chem2|NO2}} gives O(<sup>3</sup>P) via photolysis, thereby forming {{chem2|O3}} following reaction with {{chem2|O2}}.
Since hydroxyl radical is formed during the formation of {{chem2|NO2}}, the balance of the sequence of chemical reactions starting with carbon monoxide and leading to the formation of ozone is:
:{{chem2|CO + 2 O2 + hν -> CO2 + O3}}
(where hν refers to the [[photon]] of light absorbed by the {{chem2|NO2}} molecule in the sequence)

Although the creation of {{chem2|NO2}} is the critical step leading to low level [[ozone]] formation, it also increases this ozone in another, somewhat mutually exclusive way, by reducing the quantity of NO that is available to react with ozone.<ref name="NA">{{Cite book|url=https://books.google.com/books?id=QkErAAAAYAAJ&pg=PA23|title=Ozone and other photochemical oxidants|publisher=National Academies|year=1977|isbn=978-0-309-02531-7|page=23}}</ref>

=== Indoor air pollution ===
{{Main|Indoor air quality}}
Carbon monoxide is one of the most acutely toxic [[Indoor air quality|indoor air contaminants]]. Carbon monoxide may be emitted from tobacco smoke and generated from malfunctioning fuel burning stoves (wood, kerosene, natural gas, propane) and fuel burning heating systems (wood, oil, natural gas) and from blocked [[flue]]s connected to these appliances.<ref name="Myers-2022"/> In [[Developed country|developed countries]] the main sources of indoor CO emission come from cooking and heating devices that burn [[fossil fuel]]s and are faulty, incorrectly installed or poorly maintained.<ref name="Penney-2010">{{Citation |last1=Penney |first1=David |title=Carbon monoxide |date=2010 |work=WHO Guidelines for Indoor Air Quality: Selected Pollutants |url=https://www.ncbi.nlm.nih.gov/books/NBK138710/ |access-date=March 18, 2024 |archive-url=https://web.archive.org/web/20210308140149/https://www.ncbi.nlm.nih.gov/books/NBK138710/ |archive-date=March 8, 2021 |url-status=live |publisher=World Health Organization |language=en |isbn=978-92-890-0213-4 |oclc=696099951 |last2=Benignus |first2=Vernon |last3=Kephalopoulos |first3=Stylianos |last4=Kotzias |first4=Dimitrios |last5=Kleinman |first5=Michael |last6=Verrier |first6=Agnes}}</ref> Appliance malfunction may be due to faulty installation or lack of maintenance and proper use.<ref name="Myers-2022" /> In [[Developing country|low- and middle-income countries]] the most common sources of CO in homes are burning [[Biofuel|biomass fuels]] and cigarette smoke.<ref name="Penney-2010" />

==== Mining ====
Miners refer to carbon monoxide as "[[whitedamp]]" or the "silent killer". It can be found in confined areas of poor ventilation in both surface mines and underground mines. The most common sources of carbon monoxide in mining operations are the internal combustion engine and explosives; however, in coal mines, carbon monoxide can also be found due to the low-temperature oxidation of coal.<ref>{{Cite web |title=MSHA - Occupational Illness and Injury Prevention Program - Health Topics - Carbon Monoxide |url=https://arlweb.msha.gov/illness_prevention/healthtopics/carbonmonoxide.htm |url-status=dead |archive-url=https://web.archive.org/web/20171231212725/https://arlweb.msha.gov/illness_prevention/healthtopics/carbonmonoxide.htm |archive-date=2017-12-31 |access-date=2017-12-31 |website=arlweb.msha.gov |language=en}}</ref> The idiom "[[Canary in the coal mine]]" pertained to an early warning of a carbon monoxide presence.<ref name="Hopper2021">{{Cite journal |last1=Hopper |first1=Christopher P. |last2=Zambrana |first2=Paige N. |last3=Goebel |first3=Ulrich |last4=Wollborn |first4=Jakob |date=2021-06-01 |title=A brief history of carbon monoxide and its therapeutic origins |url=https://www.sciencedirect.com/science/article/abs/pii/S1089860321000367 |journal=Nitric Oxide |language=en |volume=111-112 |pages=45–63 |doi=10.1016/j.niox.2021.04.001 |issn=1089-8603 |pmid=33838343 |s2cid=233205099}}</ref>

===Health effects===
<!--Please keep this section short, there is no need to elaborate here. Details will be more useful in the [[Carbon monoxide poisoning]] article.-->
{{Main|Carbon monoxide poisoning}}

[[Carbon monoxide poisoning]] is the most common type of fatal air poisoning in many countries. Acute exposure can also lead to long-term neurological effects such as cognitive and behavioural changes. Severe CO poisoning may lead to unconsciousness, coma and death. Chronic exposure to low concentrations of carbon monoxide may lead to lethargy, headaches, nausea, flu-like symptoms and neuropsychological and cardiovascular issues.<ref name="UK Health Security Agency">{{Cite web |date=24 May 2022 |title=Carbon monoxide: toxicological overview |url=https://www.gov.uk/government/publications/carbon-monoxide-properties-incident-management-and-toxicology/carbon-monoxide-toxicological-overview |access-date=2024-04-17 |website=UK Health Security Agency |language=en}}</ref><ref name="Myers-2022"/><ref name="Dent-2024">{{Cite journal |last1=Dent |first1=Matthew R. |last2=Rose |first2=Jason J. |last3=Tejero |first3=Jesús |last4=Gladwin |first4=Mark T. |date=2024-01-29 |title=Carbon Monoxide Poisoning: From Microbes to Therapeutics |journal=Annual Review of Medicine |language=en |volume=75 |issue=1 |pages=337–351 |doi=10.1146/annurev-med-052422-020045 |pmid=37582490 |issn=0066-4219|pmc=11160397 }}</ref>