Editing Wildfire (section)

== Impacts on humans ==

Wildfire risk is the chance that a wildfire will start in or reach a particular area and the potential loss of human values if it does. Risk is dependent on variable factors such as human activities, weather patterns, availability of wildfire fuels, and the availability or lack of resources to suppress a fire.<ref>{{cite web|publisher=Oregon State University|title=About Oregon wildfire risk|access-date=9 July 2012|url=http://oeapp.oregonexplorer.info/Wildfire/topics/topics.aspx?Res=16142|archive-url=https://archive.today/20130218072405/http://oeapp.oregonexplorer.info/Wildfire/topics/topics.aspx?Res=16142|archive-date=18 February 2013}}</ref><ref>{{cite journal |last1=Doerr |first1=Stefan H. |last2=Santín |first2=Cristina |title=Global trends in wildfire and its impacts: perceptions versus realities in a changing world |journal=[[Philosophical Transactions of the Royal Society B|Philosophical Transactions of the Royal Society B: Biological Sciences]] |date=2016 |volume=371 |issue=1696 |page=20150345 |doi=10.1098/rstb.2015.0345 |pmid=27216515 |pmc=4874420 |doi-access=free}}</ref> Wildfires have continually been a threat to human populations. However, human-induced geographic and climatic changes are exposing populations more frequently to wildfires and increasing wildfire risk. It is speculated that the increase in wildfires arises from a century of wildfire suppression coupled with the rapid expansion of human developments into fire-prone wildlands.<ref>{{cite web |url=http://www.fs.fed.us/psw/publications/documents/psw_gtr208en/psw_gtr208en_505-512_haines.pdf |title=The National Wildfire Mitigation Programs Database: State, County, and Local Efforts to Reduce Wildfire Risk |publisher=US Forest Service |access-date=19 January 2014 |url-status=live |archive-url=https://web.archive.org/web/20120907045339/http://www.fs.fed.us/psw/publications/documents/psw_gtr208en/psw_gtr208en_505-512_haines.pdf |archive-date=7 September 2012 }}</ref> Wildfires are naturally occurring events that aid in promoting forest health. Global warming and climate changes are causing an increase in temperatures and more droughts nationwide which contributes to an increase in wildfire risk.<ref>{{cite web|url=http://msutoday.msu.edu/news/2013/extreme-wildfires-may-be-fueled-by-climate-change/|title=Extreme wildfires may be fueled by climate change|publisher=Michigan State University|date=1 August 2013|access-date=1 August 2013|url-status=live|archive-url=https://web.archive.org/web/20130803213631/http://msutoday.msu.edu/news/2013/extreme-wildfires-may-be-fueled-by-climate-change/|archive-date=3 August 2013}}</ref><ref>{{Cite AV media|url=https://www.youtube.com/watch?v=-mprIejWp00|title=White House explains the link between Climate Change and Wild Fires|date=5 August 2014|work=YouTube|author=Rajamanickam Antonimuthu|url-status=live|archive-url=https://web.archive.org/web/20140811074119/https://www.youtube.com/watch?v=-mprIejWp00|archive-date=11 August 2014}}</ref>
{{wide image|2009 California Wildfires at JPL - Pasadena, California.jpg|933px|The 2009 Station Fire burns in the foothills of the [[San Gabriel Mountains]] above the [[Jet Propulsion Laboratory]], near [[Pasadena, California]]}}

=== Airborne hazards ===
{{See also|Heavy metals#Toxicity|Health effects of wood smoke|Joss paper#Health impact}}
The most noticeable adverse effect of wildfires is the destruction of property. However, hazardous chemicals released also significantly impact human health.<ref>{{Cite web |date=5 February 2019 |title=How Have Forest Fires Affected Air Quality in California? |url=https://www.purakamasks.com/how-did-forest-fires-affect-air-quality-in-california |access-date=11 February 2019 |website=www.purakamasks.com |language=en}}{{Dead link|date=February 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

Wildfire smoke is composed primarily of carbon dioxide and water vapor. Other common components present in lower concentrations are carbon monoxide, formaldehyde, [[acrolein]], polyaromatic hydrocarbons, and benzene.<ref name="oehha.ca.gov">{{Cite web |last=Office of Environmental Health Hazard Assessment |year=2008 |title=Wildfire smoke: A guide for public health officials |url=http://oehha.ca.gov/air/risk_assess/wildfirev8.pdf |url-status=live |archive-url=https://web.archive.org/web/20120516071549/http://www.oehha.ca.gov/air/risk_assess/wildfirev8.pdf |archive-date=16 May 2012 |access-date=9 July 2012}}</ref> Small airborne particulates (in solid form or liquid droplets) are also present in smoke and ash debris. 80–90% of wildfire smoke, by mass, is within the fine particle size class of 2.5 micrometers in diameter or smaller.<ref>{{Cite web |last=National Wildlife Coordination Group |year=2001 |title=Smoke management guide for prescribed and wildland fire |url=http://www.fs.fed.us/pnw/pubs/ottmar-smoke-management-guide.pdf |url-status=live |archive-url=https://web.archive.org/web/20161011200515/http://www.fs.fed.us/pnw/pubs/ottmar-smoke-management-guide.pdf |archive-date=11 October 2016 |publisher=National Interagency Fire Center |location=Boise, ID}}</ref>

Carbon dioxide in smoke poses a low health risk due to its low toxicity. Rather, carbon monoxide and fine [[particulate matter]], particularly 2.5&nbsp;μm in diameter and smaller, have been identified as the major health threats.<ref name="oehha.ca.gov" /> High levels of [[heavy metals]], including [[lead]], [[arsenic]], [[cadmium]], and copper were found in the ash debris following the 2007 Californian wildfires. A [[national clean-up campaign]] was organised in fear of the health effects from exposure.<ref>{{Cite journal |vauthors=Finlay SE, Moffat A, Gazzard R, Baker D, Murray V |date=November 2012 |title=Health impacts of wildfires |journal=PLOS Currents |volume=4 |pages=e4f959951cce2c |doi=10.1371/4f959951cce2c |doi-broken-date=1 November 2024 |pmc=3492003 |pmid=23145351 |doi-access=free}}</ref> In the devastating California [[Camp Fire (2018)]] that killed 85 people, lead levels increased by around 50 times in the hours following the fire at a site nearby ([[Chico, California|Chico]]). [[Zinc]] concentration also increased significantly in Modesto, {{convert|150|mi|km|order=flip}} away. Heavy metals such as [[manganese]] and calcium were found in numerous California fires as well.<ref>{{Cite web |date=21 July 2021 |title=Wildfire smoke can increase hazardous toxic metals in air, study finds |url=https://www.theguardian.com/world/2021/jul/21/wildfire-smoke-air-hazardous-toxic-metals-study-california |website=the Guardian}}</ref> Other chemicals are considered to be significant hazards but are found in concentrations that are too low to cause detectable health effects.{{citation needed|date=May 2023}}

The degree of wildfire smoke exposure to an individual is dependent on the length, severity, duration, and proximity of the fire. People are exposed directly to smoke via the respiratory tract through inhalation of air pollutants. Indirectly, communities are exposed to wildfire debris that can contaminate soil and water supplies.

The [[United States Environmental Protection Agency|U.S. Environmental Protection Agency]] (EPA) developed the [[air quality index]] (AQI), a public resource that provides national air quality standard concentrations for common air pollutants. The public can use it to determine their exposure to hazardous air pollutants based on visibility range.<ref>{{Cite web |last=U.S. Environmental Protection Agency |year=2009 |title=Air quality index: A guide to air quality and health |url=http://www.epa.gov/airnow/aqi_brochure_08-09.pdf |url-status=live |archive-url=https://web.archive.org/web/20120507130507/http://www.epa.gov/airnow/aqi_brochure_08-09.pdf |archive-date=7 May 2012 |access-date=9 July 2012}}</ref>

=== Health effects ===
{{See also|Particulates|Health effects of wood smoke|Household air pollution#Health impacts}}
{{Further|Manganese poisoning|Lead poisoning|Chronic cough}}

[[File:Diaphragmatic breathing.gif|thumb|Animation of diaphragmatic breathing with the diaphragm shown in green]]

Wildfire smoke contains [[particulates]] that may have adverse effects upon the human respiratory system. Evidence of the health effects should be relayed to the public so that exposure may be limited. The evidence can also be used to influence policy to promote positive health outcomes.<ref name=":11">{{Cite journal |last1=Liu |first1=Jia Coco |last2=Wilson |first2=Ander |last3=Mickley |first3=Loretta J. |last4=Dominici |first4=Francesca |last5=Ebisu |first5=Keita |last6=Wang |first6=Yun |last7=Sulprizio |first7=Melissa P. |last8=Peng |first8=Roger D. |last9=Yue |first9=Xu |date=January 2017 |title=Wildfire-specific Fine Particulate Matter and Risk of Hospital Admissions in Urban and Rural Counties |journal=Epidemiology |language=en |volume=28 |issue=1 |pages=77–85 |doi=10.1097/ede.0000000000000556 |issn=1044-3983 |pmc=5130603 |pmid=27648592}}</ref>

Inhalation of smoke from a wildfire can be a health hazard.<ref>{{Cite web |date=11 March 2019 |title=Side Effects of Wildfire Smoke Inhalation |url=https://www.cleanairresources.com/resources/side-effects-of-wildfire-smoke-inhalation |access-date=3 April 2019 |website=www.cleanairresources.com |language=en |archive-date=9 July 2023 |archive-url=https://web.archive.org/web/20230709174432/https://www.cleanairresources.com/resources/side-effects-of-wildfire-smoke-inhalation |url-status=live }}</ref> Wildfire smoke is composed of combustion products i.e. [[carbon dioxide]], [[carbon monoxide]], [[water vapor]], [[particulate matter]], organic chemicals, [[nitrogen oxide]]s and other compounds. The principal health concern is the inhalation of particulate matter and carbon monoxide.<ref>{{cite web |title=1 Wildfire Smoke A Guide for Public Health Officials |url=http://www.epa.gov/ttnamti1/files/ambient/smoke/wildgd.pdf |url-status=live |archive-url=https://web.archive.org/web/20130509110731/http://www.epa.gov/ttnamti1/files/ambient/smoke/wildgd.pdf |archive-date=9 May 2013 |access-date=19 January 2014 |publisher=US Environmental Protection Agency}}</ref>

Particulate matter (PM) is a type of air pollution made up of particles of dust and liquid droplets. They are characterized into three categories based on particle diameter: coarse PM, fine PM, and ultrafine PM. Coarse particles are between 2.5 micrometers and 10 micrometers, fine particles measure 0.1 to 2.5 micrometers, and ultrafine particle are less than 0.1 micrometer. lmpact on the body upon inhalation varies by size. Coarse PM is filtered by the upper airways and can accumulate and cause pulmonary inflammation. This can result in eye and sinus irritation as well as sore throat and coughing.<ref name=":10">{{cite journal |last1=Forsberg |first1=Nicole T. |last2=Longo |first2=Bernadette M. |last3=Baxter |first3=Kimberly |last4=Boutté |first4=Marie |date=2012 |title=Wildfire Smoke Exposure: A Guide for the Nurse Practitioner |journal=[[The Journal for Nurse Practitioners]] |volume=8 |issue=2 |pages=98–106 |doi=10.1016/j.nurpra.2011.07.001}}</ref><ref name=":12">{{Cite journal |last1=Wu |first1=Jin-Zhun |last2=Ge |first2=Dan-Dan |last3=Zhou |first3=Lin-Fu |last4=Hou |first4=Ling-Yun |last5=Zhou |first5=Ying |last6=Li |first6=Qi-Yuan |date=June 2018 |title=Effects of particulate matter on allergic respiratory diseases |journal=Chronic Diseases and Translational Medicine |volume=4 |issue=2 |pages=95–102 |doi=10.1016/j.cdtm.2018.04.001 |issn=2095-882X |pmc=6034084 |pmid=29988900}}</ref> Coarse PM is often composed of heavier and more toxic materials that lead to short-term effects with stronger impact.<ref name=":12" />

Smaller PM moves further into the respiratory system creating issues deep into the lungs and the bloodstream.<ref name=":10" /><ref name=":12" /> In asthma patients, PM<sub>2.5</sub> causes inflammation but also increases oxidative stress in the epithelial cells. These particulates also cause apoptosis and autophagy in lung epithelial cells. Both processes damage the cells and impact cell function. This damage impacts those with respiratory conditions such as asthma where the lung tissues and function are already compromised.<ref name=":12" />  Particulates less than 0.1 micrometer are called [[ultrafine particle]] (UFP). It is a major component of wildfire smoke.<ref name="pmid32952154">{{cite journal |vauthors=Holm SM, Miller MD, Balmes JR |date=February 2021 |title=Health effects of wildfire smoke in children and public health tools: a narrative review |journal=J Expo Sci Environ Epidemiol |volume=31 |issue=1 |pages=1–20 |doi=10.1038/s41370-020-00267-4 |pmc=7502220 |pmid=32952154|bibcode=2021JESEE..31....1H }}</ref> UFP can enter the bloodstream like PM<sub>2.5–0.1</sub> however studies show that it works into the blood much quicker. The inflammation and epithelial damage done by UFP has also shown to be much more severe.<ref name=":12" /> PM<sub>2.5</sub> is of the largest concern in regards to wildfire.<ref name=":11" /> This is particularly hazardous to the very young, elderly and those with chronic conditions such as asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis and cardiovascular conditions. The illnesses most commonly associated with exposure to fine PM from wildfire smoke are bronchitis, exacerbation of asthma or COPD, and pneumonia. Symptoms of these complications include wheezing and shortness of breath and cardiovascular symptoms include chest pain, rapid heart rate and fatigue.<ref name=":10" />

==== Asthma exacerbation ====
Several epidemiological studies have demonstrated a close association between [[air pollution]] and respiratory allergic diseases such as bronchial [[asthma]].<ref name=":11" />

An observational study of smoke exposure related to the 2007 San Diego wildfires revealed an increase both in healthcare utilization and respiratory diagnoses, especially [[asthma]] among the group sampled.<ref name=":13">{{Cite journal |last1=Hutchinson |first1=Justine A. |last2=Vargo |first2=Jason |last3=Milet |first3=Meredith |last4=French |first4=Nancy H.F. |last5=Billmire |first5=Michael |last6=Johnson |first6=Jeffrey |last7=Hoshiko |first7=Sumi |date=10 July 2018 |title=The San Diego 2007 wildfires and Medi-Cal emergency department presentations, inpatient hospitalizations, and outpatient visits: An observational study of smoke exposure periods and a bidirectional case-crossover analysis |journal=PLOS Medicine |volume=15 |issue=7 |pages=e1002601 |doi=10.1371/journal.pmed.1002601 |issn=1549-1676 |pmc=6038982 |pmid=29990362 |doi-access=free}}</ref> Projected climate scenarios of wildfire occurrences predict significant increases in respiratory conditions among young children.<ref name=":13" /> PM triggers a series of biological processes including inflammatory immune response, [[oxidative stress]], which are associated with harmful changes in allergic respiratory diseases.<ref>{{Cite journal |last1=Wu |first1=Jin-Zhun |last2=Ge |first2=Dan-Dan |last3=Zhou |first3=Lin-Fu |last4=Hou |first4=Ling-Yun |last5=Zhou |first5=Ying |last6=Li |first6=Qi-Yuan |date=8 June 2018 |title=Effects of particulate matter on allergic respiratory diseases |journal=Chronic Diseases and Translational Medicine |volume=4 |issue=2 |pages=95–102 |doi=10.1016/j.cdtm.2018.04.001 |issn=2095-882X |pmc=6034084 |pmid=29988900}}</ref>

Although some studies demonstrated no significant acute changes in lung function among people with [[asthma]] related to PM from wildfires, a possible explanation for these counterintuitive findings is the increased use of [[Asthma|quick-relief medications]], such as inhalers, in response to elevated levels of smoke among those already diagnosed with [[asthma]].<ref name=":14">{{Cite journal |last1=Reid |first1=Colleen E. |last2=Brauer |first2=Michael |last3=Johnston |first3=Fay H. |last4=Jerrett |first4=Michael |last5=Balmes |first5=John R. |last6=Elliott |first6=Catherine T. |date=15 April 2016 |title=Critical Review of Health Impacts of Wildfire Smoke Exposure |journal=Environmental Health Perspectives |language=en |volume=124 |issue=9 |pages=1334–1343 |doi=10.1289/ehp.1409277 |issn=0091-6765 |pmc=5010409 |pmid=27082891|bibcode=2016EnvHP.124.1334R }}</ref>

There is consistent evidence between wildfire smoke and the exacerbation of asthma.<ref name=":14" />

Asthma is one of the most common chronic disease among children in the United States, affecting an estimated 6.2 million children.<ref>{{Cite web |date=19 October 2018 |title=American Lung Association and Asthma Fact sheet |url=http://www.lung.org/lung-health-and-diseases/lung-disease-lookup/asthma/learn-about-asthma/asthma-children-facts-sheet.html |url-status=live |archive-url=https://web.archive.org/web/20151116182804/http://www.lung.org/lung-health-and-diseases/lung-disease-lookup/asthma/learn-about-asthma/asthma-children-facts-sheet.html |archive-date=16 November 2015 |website=American Lung Association}}</ref> Research on asthma risk focuses specifically on the risk of air pollution during the gestational period. Several pathophysiology processes are involved in this. Considerable airway development occurs during the 2nd and 3rd trimesters and continues until 3 years of age.<ref>{{Cite journal |last1=Nishimura |first1=Katherine K. |last2=Galanter |first2=Joshua M. |last3=Roth |first3=Lindsey A. |last4=Oh |first4=Sam S. |last5=Thakur |first5=Neeta |last6=Nguyen |first6=Elizabeth A. |date=August 2013 |title=Early-Life Air Pollution and Asthma Risk in Minority Children. The GALA II and SAGE II Studies |journal=American Journal of Respiratory and Critical Care Medicine |language=en |volume=188 |issue=3 |pages=309–318 |doi=10.1164/rccm.201302-0264oc |issn=1073-449X |pmc=3778732 |pmid=23750510}}</ref> It is hypothesized that exposure to these toxins during this period could have consequential effects, as the epithelium of the lungs during this time could have increased permeability to toxins. Exposure to air pollution during parental and pre-natal stage could induce epigenetic changes which are responsible for the development of asthma.<ref>{{Cite journal |last1=Hsu |first1=Hsiao-Hsien Leon |last2=Chiu |first2=Yueh-Hsiu Mathilda |last3=Coull |first3=Brent A. |last4=Kloog |first4=Itai |last5=Schwartz |first5=Joel |last6=Lee |first6=Alison |date=1 November 2015 |title=Prenatal Particulate Air Pollution and Asthma Onset in Urban Children. Identifying Sensitive Windows and Sex Differences |journal=American Journal of Respiratory and Critical Care Medicine |volume=192 |issue=9 |pages=1052–1059 |doi=10.1164/rccm.201504-0658OC |issn=1535-4970 |pmc=4642201 |pmid=26176842}}</ref> Studies have found significant association between PM<sub>2.5</sub>, NO<sub>2</sub> and development of asthma during childhood despite heterogeneity among studies.<ref>{{Cite journal |last1=Hehua |first1=Zhang |last2=Qing |first2=Chang |last3=Shanyan |first3=Gao |last4=Qijun |first4=Wu |last5=Yuhong |first5=Zhao |date=November 2017 |title=The impact of prenatal exposure to air pollution on childhood wheezing and asthma: A systematic review |journal=Environmental Research |volume=159 |pages=519–530 |bibcode=2017ER....159..519H |doi=10.1016/j.envres.2017.08.038 |issn=0013-9351 |pmid=28888196 |s2cid=22300866}}</ref> Furthermore, maternal exposure to chronic stressors is most likely present in distressed communities, and as this can be correlated with childhood asthma, it may further explain links between early childhood exposure to air pollution, neighborhood poverty, and childhood risk.<ref>{{Cite journal |last1=Morello-Frosch |first1=Rachel |last2=Shenassa |first2=Edmond D. |date=August 2006 |title=The Environmental 'Riskscape' and Social Inequality: Implicationsfor Explaining Maternal and Child Health Disparities |journal=Environmental Health Perspectives |language=en |volume=114 |issue=8 |pages=1150–1153 |doi=10.1289/ehp.8930 |issn=0091-6765 |pmc=1551987 |pmid=16882517}}</ref>

==== Carbon monoxide danger ====
{{Main|Carbon monoxide poisoning}}

Carbon monoxide (CO) is a colorless, odorless gas that can be found at the highest concentration at close proximity to a smoldering fire. Thus, it is a serious threat to the health of wildfire firefighters. CO in smoke can be inhaled into the lungs where it is absorbed into the bloodstream and reduces oxygen delivery to the body's vital organs. At high concentrations, it can cause headaches, weakness, dizziness, confusion, nausea, disorientation, visual impairment, coma, and even death. Even at lower concentrations, such as those found at wildfires, individuals with cardiovascular disease may experience chest pain and cardiac arrhythmia.<ref name="oehha.ca.gov" /> A recent study tracking the number and cause of wildfire firefighter deaths from 1990 to 2006 found that 21.9% of the deaths occurred from heart attacks.<ref>{{cite web |author=National Wildfire Coordinating Group |date=June 2007 |title=Wildland firefighter fatalities in the United States 1990–2006 |url=http://www.nwcg.gov/pms/pubs/pms841/pms841_all-72dpi.pdf |url-status=live |archive-url=https://web.archive.org/web/20120315081248/http://www.nwcg.gov/pms/pubs/pms841/pms841_all-72dpi.pdf |archive-date=15 March 2012 |publisher=NWCG Safety and Health Working Team}}</ref>

Another important and somewhat less obvious health effect of wildfires is psychiatric diseases and disorders. Both adults and children from various countries who were directly and indirectly affected by wildfires were found to demonstrate different mental conditions linked to their experience with the wildfires. These include [[Post-traumatic stress disorder among athletes|post-traumatic stress disorder]] (PTSD), [[Depression (mood)|depression]], anxiety, and [[phobia]]s.<ref>{{cite journal |last1=Papanikolaou |first1=V. |last2=Adamis |first2=D. |last3=Mellon |first3=R.C. |last4=Prodromitis |first4=G. |date=2011 |title=Psychological distress following wildfires disaster in a rural part of Greece: A case-control population-based study |journal=International Journal of Emergency Mental Health |volume=13 |issue=1 |pages=11–26 |pmid=21957753}}</ref><ref>{{cite journal |last1=Mellon |first1=Robert C. |last2=Papanikolau |first2=Vasiliki |last3=Prodromitis |first3=Gerasimos |date=2009 |title=Locus of control and psychopathology in relation to levels of trauma and loss: Self-reports of Peloponnesian wildfire survivors |journal=Journal of Traumatic Stress |volume=22 |issue=3 |pages=189–196 |doi=10.1002/jts.20411 |pmid=19452533}}</ref><ref>{{cite journal |last1=Marshall |first1=G.N. |last2=Schell |first2=T.L. |last3=Elliott |first3=M.N. |last4=Rayburn |first4=N.R. |last5=Jaycox |first5=L.H. |date=2007 |title=Psychiatric Disorders Among Adults Seeking Emergency Disaster Assistance After a Wildland-Urban Interface Fire |journal=Psychiatric Services |volume=58 |issue=4 |pages=509–514 |doi=10.1176/appi.ps.58.4.509 |pmid=17412853}}</ref><ref>{{cite journal |last1=McDermott |first1=Brett M |last2=Lee |first2=Erica M |last3=Judd |first3=Marianne |last4=Gibbon |first4=Peter |title=Posttraumatic Stress Disorder and General Psychopathology in Children and Adolescents following a Wildfire Disaster |journal=The Canadian Journal of Psychiatry |date=March 2005 |volume=50 |issue=3 |pages=137–143 |doi=10.1177/070674370505000302 |pmid=15830823 }}</ref><ref>{{cite journal |last1=Jones |first1=R.T.|last2=Ribbe |first2=D.P. |last3=Cunningham |first3=P.B. |last4=Weddle |first4=J.D. |last5=Langley |first5=A.K. |date=2002 |title=Psychological impact of fire disaster on children and their parents |journal=Behavior Modification |volume=26 |issue=2 |pages=163–186 |doi=10.1177/0145445502026002003 |pmid=11961911 }}</ref>

==== Epidemiology ====
{{Globalize section|date=July 2023|United States}}
The Western US has seen an increase in both the frequency and intensity of wildfires over the last several decades. This has been attributed to the arid climate of there and the effects of global warming. An estimated 46 million people were exposed to wildfire smoke from 2004 to 2009 in the Western US. Evidence has demonstrated that wildfire smoke can increase levels of airborne particulate.<ref name=":11" />

The EPA has defined acceptable concentrations of PM in the air, through the National Ambient Air Quality Standards and monitoring of ambient air quality has been mandated.<ref name=":15">{{cite web |date=24 April 2016 |title=Particulate Matter (PM) Standards |url=http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html |url-status=live |archive-url=https://web.archive.org/web/20120815125540/http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html |archive-date=15 August 2012 |publisher=EPA}}</ref> Due to these monitoring programs and the incidence of several large wildfires near populated areas, epidemiological studies have been conducted and demonstrate an association between human health effects and an increase in fine particulate matter due to wildfire smoke.

An increase in PM smoke emitted from the Hayman fire in Colorado in June 2002, was associated with an increase in respiratory symptoms in patients with COPD.<ref>{{cite journal |last1=Sutherland |first1=E. Rand |last2=Make |first2=Barry J. |last3=Vedal |first3=Sverre |last4=Zhang |first4=Lening |last5=Dutton |first5=Steven J. |last6=Murphy |first6=James R. |last7=Silkoff |first7=Philip E. |date=2005 |title=Wildfire smoke and respiratory symptoms in patients with chronic obstructive pulmonary disease |journal=Journal of Allergy and Clinical Immunology |volume=115 |issue=2 |pages=420–422 |doi=10.1016/j.jaci.2004.11.030 |pmid=15696107}}</ref> Looking at the wildfires in Southern California in 2003, investigators have shown an increase in hospital admissions due to asthma symptoms while being exposed to peak concentrations of PM in smoke.<ref>{{cite journal |last1=Delfino |first1=R.J. |last2=Brummel |first2=S |last3=Wu |first3=J. |last4=Stern |first4=H. |last5=Ostro |first5=B. |last6=Lipsett |first6=M. |last10=Tjoa |first10=T.|last11=Gillen |first11=D.L. |date=2009 |title=The relationship of respiratory and cardiovascular hospital admissions to the southern California wildfires of 2003 |journal=Occupational and Environmental Medicine |volume=66 |issue=3 |pages=189–197 |doi=10.1136/oem.2008.041376 |pmc=4176821 |pmid=19017694}}</ref> Another epidemiological study found a 7.2% (95% confidence interval: 0.25%, 15%) increase in risk of respiratory related hospital admissions during smoke wave days with high wildfire-specific particulate matter 2.5 compared to matched non-smoke-wave days.<ref name=":11" />

Children participating in the Children's Health Study were also found to have an increase in eye and respiratory symptoms, medication use and physician visits.<ref>{{cite journal |last1=Kunzli |first1=N. |last2=Avol |first2=E. |last3=Wu |first3=J. |last4=Gauderman |first4=W.J. |last5=Rappaport |first5=E. |last6=Millstein |first6=J. |date=2006 |title=Health Effects of the 2003 Southern California Wildfires on Children |journal=American Journal of Respiratory and Critical Care Medicine |volume=174 |issue=11 |pages=1221–1228 |doi=10.1164/rccm.200604-519OC |pmc=2648104 |pmid=16946126}}</ref> Mothers who were pregnant during the fires gave birth to babies with a slightly reduced average birth weight compared to those who were not exposed. Suggesting that pregnant women may also be at greater risk to adverse effects from wildfire.<ref>{{cite journal |last1=Holstius |first1=David M. |last2=Reid |first2=Colleen E. |last3=Jesdale |first3=Bill M. |last4=Morello-Frosch |first4=Rachel |date=2012 |title=Birth Weight Following Pregnancy During the 2003 Southern California Wildfires |journal=Environmental Health Perspectives |volume=120 |issue=9 |pages=1340–1345 |doi=10.1289/ehp.1104515 |pmc=3440113 |pmid=22645279|bibcode=2012EnvHP.120.1340H }}</ref> Worldwide, it is estimated that 339,000 people die due to the effects of wildfire smoke each year.<ref>{{cite journal |last1=Johnston |first1=Fay H. |last2=Henderson |first2=Sarah B. |last3=Chen |first3=Yang |last4=Randerson |first4=James T. |last5=Marlier |first5=Miriam |last6=DeFries |first6=Ruth S. |last7=Kinney |first7=Patrick |last8=Bowman |first8=David M.J.S. |last9=Brauer |first9=Michael |title=Estimated Global Mortality Attributable to Smoke from Landscape Fires |journal=Environmental Health Perspectives |date=May 2012 |volume=120 |issue=5 |pages=695–701 |doi=10.1289/ehp.1104422 |pmid=22456494 |pmc=3346787 |bibcode=2012EnvHP.120..695J }}</ref>

Besides the size of PM, their chemical composition should also be considered. Antecedent studies have demonstrated that the chemical composition of PM<sub>2.5</sub> from wildfire smoke can yield different estimates of human health outcomes as compared to other sources of smoke such as solid fuels.<ref name=":11" />[[File:Sediment off the Yucatan Peninsula.jpg|thumb|Sediment off the Yucatán Peninsula]]

=== Post-fire risks ===
[[File:Prospect Hill bushfire.jpg|thumb|Charred shrubland in suburban [[Sydney]] ([[2019–20 Australian bushfire season|2019–20 Australian bushfires]]).]]
After a wildfire, hazards remain. Residents returning to their homes may be at risk from falling fire-weakened trees. Humans and pets may also be harmed by falling into [[ash pit]]s. The Intergovernmental Panel on Climate Change (IPCC) also reports that wildfires cause significant damage to electric systems, especially in dry regions.<ref>{{Cite web |url=https://report.ipcc.ch/ar6wg3/index.html |title=IPCC Sixth Assessment Report 2022 |access-date=7 April 2022 |archive-date=4 April 2022 |archive-url=https://web.archive.org/web/20220404162105/https://report.ipcc.ch/ar6wg3/index.html }}</ref>

[[Chemically contaminated drinking water]], at levels of hazardous waste concern, is a growing problem. In particular, hazardous waste scale chemical contamination of buried water systems was first discovered in the U.S. in 2017,<ref>{{cite journal | doi=10.1002/aws2.1183 | title=Wildfire caused widespread drinking water distribution network contamination | date=2020 | last1=Proctor | first1=Caitlin R. | last2=Lee | first2=Juneseok | last3=Yu | first3=David | last4=Shah | first4=Amisha D. | last5=Whelton | first5=Andrew J. | journal=AWWA Water Science | volume=2 | issue=4 | bibcode=2020AWWWS...2E1183P | s2cid=225641536 }}</ref> and has since been increasingly documented in Hawaii, Colorado, and Oregon after wildfires.<ref>{{cite journal | doi=10.1002/aws2.1318 | title=The Marshall Fire: Scientific and policy needs for water system disaster response | date=2023 | last1=Whelton | first1=Andrew J. | last2=Seidel | first2=Chad | last3=Wham | first3=Brad P. | last4=Fischer | first4=Erica C. | last5=Isaacson | first5=Kristofer | last6=Jankowski | first6=Caroline | last7=MacArthur | first7=Nathan | last8=McKenna | first8=Elizabeth | last9=Ley | first9=Christian | journal=AWWA Water Science | volume=5 | issue=1 | bibcode=2023AWWWS...5E1318W | doi-access=free }}</ref> In 2021, Canadian authorities adapted their post-fire public safety investigation approaches in British Columbia to screen for this risk, but have not found it as of 2023. Another challenge is that private drinking wells and the plumbing within a building can also become chemically contaminated and unsafe.<ref>{{cite journal | doi=10.1002/aws2.1319 | title=Wildfire damage and contamination to private drinking water wells | date=2023 | last1=Jankowski | first1=Caroline | last2=Isaacson | first2=Kristofer | last3=Larsen | first3=Madeline | last4=Ley | first4=Christian | last5=Cook | first5=Myles | last6=Whelton | first6=Andrew J. | journal=AWWA Water Science | volume=5 | issue=1 | bibcode=2023AWWWS...5E1319J | doi-access=free }}</ref> Households experience a wide-variety of significant economic and health impacts related to this contaminated water.<ref>{{cite journal |doi=10.1007/s11069-021-04714-9 |title=Water safety attitudes, risk perception, experiences, and education for households impacted by the 2018 Camp Fire, California |date=3 May 2021 |first1=Tolulope O. |last1=Odimayomi |first2=Caitlin R. |last2=Proctor |first3=Qi Erica |last3=Wang |first4=Arman |last4=Sabbaghi |first5=Kimberly S. |last5=Peterson |first6=David J. |last6=Yu |first7=Juneseok |last7=Lee |first8=Amisha D. |last8=Shah |first9=Christian J. |last9=Ley |first10=Yoorae |last10=Noh |first11=Charlotte D. |last11=Smith |first12=Jackson P. |last12=Webster |first13=Kristin |last13=Milinkevich |first14=Michael W. |last14=Lodewyk |first15=Julie A. |last15=Jenks |first16=James F. |last16=Smith |first17=Andrew J. |last17=Whelton |journal=Natural Hazards |volume=108 |issue=1 |pages=947–975|bibcode=2021NatHa.108..947O }}</ref> Evidence-based guidance on how to inspect and test wildfire impacted wells <ref>{{cite web |url=https://engineering.purdue.edu/PlumbingSafety/resources/After-a-Wildfire-Private-Drinking-Water-Wells-2021-05-16.pdf |title=After a Wildfire: Water Safety Considerations for Private Wells |date=16 May 2021 |publisher=Purdue University}}</ref> and building water systems was developed for the first time in 2020.<ref>{{cite web |url=https://engineering.purdue.edu/PlumbingSafety/resources/After-a-Wildfire-Water-Safety-in-Buildings-2021-05-16.pdf |title=After a Wildfire: Water Safety Considerations Inside Buildings |date=16 May 2021 |publisher=Purdue University |access-date=17 December 2023 |archive-date=17 December 2023 |archive-url=https://web.archive.org/web/20231217071449/https://engineering.purdue.edu/PlumbingSafety/resources/After-a-Wildfire-Water-Safety-in-Buildings-2021-05-16.pdf |url-status=live }}</ref> In Paradise, California, for example,<ref>{{cite web | url=https://www.civilbeat.org/2023/12/fire-destroyed-this-california-towns-water-system-but-that-didnt-slow-the-effort-to-rebuild/ | title=Fire Destroyed This California Town's Water System. But That Didn't Slow the Effort to Rebuild | date=12 December 2023 | access-date=17 December 2023 | archive-date=17 December 2023 | archive-url=https://web.archive.org/web/20231217071449/https://www.civilbeat.org/2023/12/fire-destroyed-this-california-towns-water-system-but-that-didnt-slow-the-effort-to-rebuild/ | url-status=live }}</ref> the 2018 Camp Fire caused more than $150 million dollars worth of damage. This required almost a year of time to decontaminate and repair the municipal drinking water system from wildfire damage.

The source of this contamination was first proposed after the 2018 Camp Fire in California as originating from thermally degraded plastics in water systems, smoke and vapors entering depressurized plumbing, and contaminated water in buildings being sucked into the municipal water system. In 2020, it was first shown that thermal degradation of plastic drinking water materials was one potential contamination source.<ref>{{cite journal | doi=10.1039/D0EW00836B | title=Drinking water contamination from the thermal degradation of plastics: Implications for wildfire and structure fire response | date=2021 | last1=Isaacson | first1=Kristofer P. | last2=Proctor | first2=Caitlin R. | last3=Wang | first3=Q. Erica | last4=Edwards | first4=Ethan Y. | last5=Noh | first5=Yoorae | last6=Shah | first6=Amisha D. | last7=Whelton | first7=Andrew J. | journal=Environmental Science: Water Research & Technology | volume=7 | issue=2 | pages=274–284 | doi-access=free }}</ref> In 2023, the second theory was confirmed where contamination could be sucked into pipes that lost water pressure.<ref>{{cite journal | doi=10.1007/s10694-023-01487-4 | title=Pilot Study on Fire Effluent Condensate from Full Scale Residential Fires | date=2023 | last1=Horn | first1=Gavin P. | last2=Dow | first2=Nicholas W. | last3=Neumann | first3=Danielle L. | journal=Fire Technology | volume=60 | pages=1–18 | doi-access=free }}</ref>

Other post-fire risks, can increase if other [[extreme weather]] follows. For example, wildfires make soil less able to absorb precipitation, so heavy rainfall can result in more severe [[flooding]] and damages like [[mud slide]]s.<ref>{{cite book |doi=10.1061/9780784482834.019 |chapter=Post-Fire Mudflow Prevention by Biopolymer Treatment of Water Repellent Slopes |title=Geo-Congress 2020 |date=2020 |last1=Movasat |first1=Mahta |last2=Tomac |first2=Ingrid |pages=170–178 |isbn=978-0-7844-8283-4 }}</ref><ref>{{Cite journal |last=Palmer |first=Jane |date=12 January 2022 |title=The devastating mudslides that follow forest fires |journal=Nature |volume=601 |issue=7892 |pages=184–186 |doi=10.1038/d41586-022-00028-3 |pmid=35022598 |bibcode=2022Natur.601..184P |doi-access=free }}</ref>

=== At-risk groups ===

==== Firefighters ====
{{Main|Firefighting}}
Firefighters are at greatest risk for acute and chronic health effects resulting from wildfire smoke exposure. Some of the most common health conditions that firefighters acquire from prolonged smoke inhalation include cardiovascular and respiratory diseases.<ref>{{Cite web |last=Slavik |last2=Chapman |last3=Cohen |last4=Bendefaa |last5=Peters |first=Catherine |first2=Daniel |first3=Alex |first4=Nahla |first5=Ellen |date=December 8, 2024 |title=Clearing the air: evaluating institutions' social media health message on wildfire and smoke risks in the US Pacific Noethwest |url=https://media.proquest.com/media/hms/PFT/1/CB1LX?hl=hazard%252Chazards%252Cwildfire%252Cwildfires%252Chealth%252Chealths&cit%253Aauth=Slavik%252C+Catherine+E%253BChapman%252C+Daniel+A%253BAlex+Segr%C3%A8+Cohen%253BBendefaa%252C+Nahla%253BPeters%252C+Ellen&cit%253Atitle=Clearing+the+air%253A+evaluating+institutions%E2%80%99+social+media+health+...&cit%253Apub=BMC+Public+Health&cit%253Avol=24&cit%253Aiss=&cit%253Apg=1&cit%253Adate=2024&ic=true&cit%253Aprod=ProQuest+Central&_a=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&_s=1P1gw%252BBPmUNk3XFlQzX9rfDUiRA%253D#view=fitH&statusbar=1}}</ref> For example, wildland firefighters can get hypoxia, which is a condition in which the body does not receive enough oxygen.<ref>{{Cite web |last=Broyles |first=George |date=October 2013 |title=Wildland Firefighter Smoke Exposure |url=https://www.fs.usda.gov/t-d/pubs/pdfpubs/pdf13511803/pdf13511803dpi100.pdf}}</ref> Due to firefighters' occupational duties, they are frequently exposed to [[Chemical hazard|hazardous chemicals]] at close proximity for longer periods of time. A case study on the exposure of wildfire smoke among wildland firefighters shows that firefighters are exposed to significant levels of carbon monoxide and respiratory irritants above [[Occupational Safety and Health Administration|OSHA]]-permissible exposure limits (PEL) and ACGIH threshold limit values (TLV). 5–10% are overexposed.<ref>{{cite journal |last1=Booze |first1=Thomas F. |last2=Reinhardt |first2=Timothy E. |last3=Quiring |first3=Sharon J. |last4=Ottmar |first4=Roger D. |title=A Screening-Level Assessment of the Health Risks of Chronic Smoke Exposure for Wildland Firefighters |journal=Journal of Occupational and Environmental Hygiene |date=May 2004 |volume=1 |issue=5 |pages=296–305 |doi=10.1080/15459620490442500 |pmid=15238338 }}</ref> 

Between 2001 and 2012, over 200 [[Occupational fatality|fatalities]] occurred among wildland firefighters. In addition to heat and chemical hazards, firefighters are also at risk for electrocution from power lines; injuries from equipment; [[Occupational injury|slips, trips, and falls]]; injuries from vehicle rollovers; [[Heat illness|heat-related illness]]; [[insect bites and stings]]; [[Occupational stress|stress]]; and [[rhabdomyolysis]].<ref>{{Cite journal|url=https://www.cdc.gov/niosh/docs/2013-158/|title=CDC – NIOSH Publications and Products – Wildland Fire Fighting: Hot Tips to Stay Safe and Healthy (2013–158)|website=www.cdc.gov|access-date=22 November 2016|url-status=live|archive-url=https://web.archive.org/web/20161122154309/http://www.cdc.gov/niosh/docs/2013-158/|archive-date=22 November 2016|doi=10.26616/NIOSHPUB2013158|year=2013|doi-access=free}}</ref> Wildfires that reach urban environments create additional toxic fumes and carcinogenic particles from burning metals, plastics, electronics, paints, and other common materials.<ref name="s261">{{cite web | last=Wittenberg | first=Ariel | title=Los Angeles Firefighters Risk Cancer from Urban Smoke | website=Scientific American | date=2025-01-13 | url=https://www.scientificamerican.com/article/los-angeles-firefighters-risk-cancer-from-urban-smoke/ | access-date=2025-04-08}}</ref>

==== Residents ====
[[File:North Complex smoke in San Francisco - Bay Bridge and Financial District.jpg|thumb|Smoke from the [[2020 California wildfires]] settles over [[San Francisco]]]]
Residents in communities surrounding wildfires are exposed to lower concentrations of chemicals, but they are at a greater risk for indirect exposure through water or [[soil contamination]]. Exposure to residents is greatly dependent on individual susceptibility. Vulnerable persons such as children (ages 0–4), the elderly (ages 65 and older), smokers, and pregnant women are at an increased risk due to their already compromised body systems, even when the exposures are present at low chemical concentrations and for relatively short exposure periods.<ref name="oehha.ca.gov" /> They are also at risk for future wildfires and may move away to areas they consider less risky.<ref>{{cite news |title=Living under a time bomb |url=https://www.washingtonpost.com/news/national/wp/2018/12/12/feature/living-under-a-time-bomb-california-communities-scramble-to-avoid-becoming-the-next-wildfire-tragedy/?noredirect=on&wpisrc=nl_rainbow&wpmm=1 |access-date=15 December 2018 |newspaper=[[The Washington Post]] |language=en |archive-date=24 January 2021 |archive-url=https://web.archive.org/web/20210124160550/https://www.washingtonpost.com/news/national/wp/2018/12/12/feature/living-under-a-time-bomb-california-communities-scramble-to-avoid-becoming-the-next-wildfire-tragedy/?noredirect=on&wpisrc=nl_rainbow&wpmm=1 |url-status=live }}</ref>

Wildfires affect large numbers of people in Western Canada and the United States. In California alone, more than 350,000 people live in towns and cities in "very high fire hazard severity zones".<ref name="rgj">{{cite news|page=1A |title=A real life gamble: California races to predict which town could be the next victim | author1=Ryan Sabalow |author2=Phillip Reese |author3=Dale Kasler |agency=The Sacramento Bee | publisher=Reno Gazette Journal |work=Destined to Burn}}</ref>

Direct risks to building residents in fire-prone areas can be moderated through design choices such as choosing fire-resistant vegetation, maintaining landscaping to avoid debris accumulation and to create firebreaks, and by selecting fire-retardant roofing materials. Potential compounding issues with poor air quality and heat during warmer months may be addressed with MERV 11 or higher outdoor air filtration in building ventilation systems, mechanical cooling, and a provision of a refuge area with additional air cleaning and cooling, if needed.<ref>{{cite web |title=Design Discussion Primer – Wildfires |url=https://www.bchousing.org/publications/MBAR-Wildfires.pdf |publisher=BC Housing |access-date=16 July 2021 |archive-date=20 December 2022 |archive-url=https://web.archive.org/web/20221220155847/https://www.bchousing.org/publications/MBAR-Wildfires.pdf |url-status=live }}</ref>