REVIEW ARTICLE Unclean cooking fuel use and all health outcomes, a systematic review and meta-analysis Damiano Pizzola, Mike Trottb,c, Dong Keon Yond, Masoud Rahmatie,f,g, Jae Il Shinh, Barbara Kamholzi, Biraj Karmacharyaj, Prabha Shresthaj,k,l, Benjamin R. Underwoodm, Laurie Butlern, Yvonne Barnettn, Nicola Veroneseo, Pinar Soysalp, Guillermo Gomeza, Simone Mortaraa, Eugenio Malfattiq, Sanjiv Ahluwaliar, Alice Concaria, Alice Corinaldia, Tatiana Marrufos, Filippo Ubertia, Guillermo F. L�opez S�anchezt and Lee Smithn aHealth Unit, Eni, San Donato Milanese, Italy; bQueensland Centre for Mental Health Research, Faculty of Medicine, University of Queensland, Brisbane, Australia; cMetro South Addition and Mental Health Services, Brisbane, Australia; dCenter for Digital Health, Medical Science Research Institute, Kyung Hee University Medical Center, Kyung Hee University College of Medicine, Seoul, South Korea; eCEReSS-Health Service Research and Quality of Life Center, Aix-Marseille University, Marseille, France; fDepartment of Physical Education and Sport Sciences, Faculty of Literature and Human Sciences, Lorestan University, Khoramabad, Iran; gDepartment of Physical Education and Sport Sciences, Faculty of Literature and Humanities, Vali-E-Asr University of Rafsanjan, Rafsanjan, Iran; hDepartment of Pediatrics, Yonsei University College of Medicine, Seoul, South Korea; iDepartment of Psychiatry, University of California, San Francisco, California, USA; jDepartment of Public Health and Community Programs, Dhulikhel Hospital, Kathmandu University School of Medical Sciences, Panauti, Nepal; kGlobal Brain Health Institute, University of California San Francisco, San Francisco, California, USA; lDepartment of Nursing and Midwifery, Kathmandu University School of Medical Sciences, Nepal; mDepartment of Psychiatry, University of Cambridge, Windsor Unit, Fulbourn Hospital, Cambridge, UK; nCentre for Health, Performance, and Wellbeing, Anglia Ruskin University, Cambridge, UK; oFaculty of Medicine, Saint Camillus International University of Health Sciences, Rome, Italy; pDepartment of Geriatric Medicine, Faculty of Medicine, Bezmialem Vakif University, Istanbul, Turkey; qHealth Unit, Eni Rovuma, Maputo, Mozambique; rSchool of Medicine, Faculty of Health, Medicine and Social Care, Anglia Ruskin University, Chelmsford, UK; sIstituto Nacional de Saude, Maputo, Mozambique; tDivision of Preventive Medicine and Public Health, Department of Public Health Sciences, School of Medicine, University of Murcia, Murcia, Spain ABSTRACT A large and growing body of evidence suggests that unclean cooking fuel use impacts phys- ical and mental health. However, to date, this evidence has not been collated or evaluated in a systematic manner. The aim of this systematic review and meta-analysis was to assess the strength of the associations between unclean cooking fuel use and physical and mental health outcomes. The following databases: PubMed/Medline, Scopus, Embase, Web of Science, CINAHL, Greenlife and CAB were systematically searched for studies investigating the association between cooking fuel and health outcomes up to 25th September 2023. Humans of any age using unclean and/or clean cooking fuels were eligible. Subsequently, data from included studies were converted into odds ratios (ORs), and meta-analysis was car- ried out. A total of 122 studies were included with a total of 3,728,989 cookstove users of which 2,430,194 were unclean cooking fuel users. Using unclean cooking fuels were posi- tively associated with several comorbidities, including digestive disease (OR ¼ 1.37), respira- tory infection (OR ¼ 1.52), respiratory disease (OR ¼ 1.59), anemia (OR ¼ 1.61), cognitive impairment (OR ¼ 1.70), chronic bronchitis (OR ¼ 1.84), depression (OR ¼ 1.92), chronic cough (OR ¼ 2.23), COPD (OR ¼ 2.37), and eye irritation (OR ¼ 4.19) compared to clean cooking fuel use. ARTICLE HISTORY Received 1 October 2024 Revised 22 January 2025 Accepted 23 January 2025 KEYWORDS Cooking; cooking fuels; health outcomes; meta- analysis Background Unclean cooking fuels, including kerosene/paraffin, and solid fuels (coal/charcoal, wood, agriculture/crop, ani- mal dung, shrubs/grass) are key risk factors for diseases and mortality, specifically in low- and middle-income countries (LMICs) which are becoming a growing concern in relation to public health (Smith et al., 2023). It has been estimated that 3 billion people use traditional biomass such as fuelwood, as their main source of cooking fuels (Twumasi et al., 2021). Furthermore, on a global scale, access to clean cooking fuel is not equally distributed. For example, the access rate to clean cooking fuels increased by about 1% per year between 2010 CONTACT Lee Smith lee.smith@aru.ac.uk Centre for Health, Performance, and Wellbeing, Anglia Ruskin University, Cambridge, UK Supplemental data for this article can be accessed online at https://doi.org/10.1080/29963257.2025.2463654. � 2025 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The terms on which this article has been published allow the posting of the Accepted Manuscript in a repository by the author(s) or with their consent. HEALTH INTERACTIONS 2025, VOL. 1, NO. 1, 2463654 https://doi.org/10.1080/29963257.2025.2463654 http://crossmark.crossref.org/dialog/?doi=10.1080/29963257.2025.2463654&domain=pdf&date_stamp=2025-02-22 http://orcid.org/0000-0002-9897-5273 https://doi.org/10.1080/29963257.2025.2463654 http://creativecommons.org/licenses/by/4.0/ https://doi.org/10.1080/29963257.2025.2463654 to 2019. This rise in access was predominantly owing to improvements in five LMICs: Brazil, China, India, Indonesia and Pakistan whereas stable rates were observed in other LMICs (World Health Organization, 2022). In 2030 it is estimated that approximately 1/3 of the global population will still be using unclean cooking fuels with the highest prevalence likely in Sub-Saharan Africa (World Health Organization, 2022). There are plausible direct mechanisms that link unclean cooking fuel use to multiple physical and mental health outcomes. For example, cooking with biomass fuels at home releases a significant quantity of pollu- tants that are subsequently inhaled. Importantly, such exposure to particulate matter results in negative phys- ical and mental health complications potentially via increased levels of oxidative stress and inflammatory reactions (Deng et al., 2022). Indeed, both oxidative stress and inflammation are associated with many health complications that are also associated with unclean cooking fuel use. Indeed, inflammation and reactive oxy- gen species (ROS) are implicated in neural and cardiovascular function, but, accumulation of these in the brain or cardiac tissue are key mechanisms in disease development. Moreover, inflammation is increasingly implicated in neurodegenerative and mental health conditions (Maayan & Maayan, 2024; Zhou et al., 2023). While several studies currently exist using multiple designs on unclean cooking fuel use and multiple single health outcomes, as well as global estimates, no attempt until now has been made to systematically collate and evaluate the extent literature on the relationship between unclean cooking fuel use and all health outcomes (phys- ical and mental), utilizing a systematic review and meta-analysis, into one informative report. The aim of the pre- sent systematic review and meta-analysis was to investigate strength of the associations between unclean cooking fuel use and physical and mental health outcomes. Understanding these associations is essential to bolster adop- tion of the United Nations Sustainable Development Goal (SDG) 7 ‘ensure access to affordable, reliable, sustain- able and modern energy for all’ (United Nations, 2021) and thus findings may subsequently support the reallocation of resources to eliminate unclean cooking fuel use. Ultimately, such reallocation needs to derive from policy and thus the findings from this study will be pertinent to policy makers working in this arena. Methods The present systematic review followed the PRISMA (Page et al., 2021) and MOOSE (Stroup et al., 2000) statements and the review protocol was pre-registered on PROSPERO (CRD42024520533). Search strategy Two researchers (LS and DP) independently carried out a literature search using PubMed/Medline, Scopus, Embase, Web of Science, CINAHL, Greenlife and CAB databases from inception to the 25th of September 2023. The following search strategy was used: (health outcomes OR morbidity OR morbidities OR morbid OR illnesses OR illness OR disease OR diseases OR health outcomes OR pathology OR pathologies) AND (clean� fuel� OR clean� energy OR clean cooking OR unclean� fuel� OR unclean� energy OR unclean cooking OR stove� OR cookstove� OR log stove� OR gas stove� OR electric stove� OR ethanol stove� OR ethanol burner� OR gas burner� OR gas cooktop� OR biomass pellet stove�). The references of included articles as well as con- ference proceedings were also reviewed to identify other potentially eligible studies that may had been missed in the initial search. Two investigators independently conducted the assessment of inclusion and exclusion cri- teria, quality assessment of studies and extraction of data (MT, DP). The results were then compared and any disagreement was resolved through discussion with a third senior investigator (LS). Type of studies, inclusion, and exclusion criteria Utilizing the PICOS (participants, intervention, controls, outcomes, study design) criteria, we included studies that assessed: P: Humans of any age using unclean cooking fuels, including kerosene/paraffin, and solid fuels (coal/char- coal, wood, agriculture/crop, animal dung, shrubs/grass). I: None C: Humans using clean cooking fuels (e.g. electricity, liquid petroleum gas, natural gas, biogas). O: All measured health outcomes. S: Observational studies (cross-sectional, cohort studies, retrospective studies, case control studies, and longi- tudinal) on cooking fuel and health outcomes. 2 D. PIZZOL ET AL. Articles that were included were published in English only, on humans only, and participants of any age. Articles that were excluded were those that were theoretical, of a qualitative nature, case studies, conference abstracts, and experimental trials. Data extraction For eligible studies, two researchers (MT, DP) independently extracted the following: first author name, year of publication, country, study design, sample size, sample characteristics, exposures, and outcomes. Assessment of study quality Two authors (DP and MT) independently assessed the quality of studies using the Newcastle-Ottawa Scale (NOS) (Wells et al., 2000). The NOS uses three quality parameters: selection, comparability, and outcome and assigns a maximum of 9 points. Following standard procedure, studies were graded as having a high (<5 stars), moderate (5–7 stars) or low (�8 stars) risk of bias. Any disagreements between the two authors were discussed and agreed by consensus with a third author (LS). Statistical analysis All data on comorbidities and clean cooking status were extracted and converted into odds ratios (ORs). All analyses were conducted in R (R Foundation for Statistical Computing Austria, 2019). ORs stratified by the type of comorbidity were meta-analysed using the restricted maximum likelihood method, weighting studies based on the inverse variance, using the ‘metabin’ package (Balduzzi et al., 2019). Heterogeneity was determined using the I2 statistic. Publication bias was assessed using Egger’s test if k studies >10, and by vis- ual inspection of funnel plots if k ¼<10. The credibility of results was classified according to the GRADE criteria (Guyatt et al., 2008), based on guidelines proposed by Sch€unemann et al (Sch€unemann et al., 2019). Results Literature search As shown in Figure 1, we initially found 5,340 possibly eligible articles (Figure 1). After removing 5,181 articles through the title/abstract screening, 159 were retrieved as full text. Of the 159 full text articles, 37 studies were excluded due to lack of relevant outcomes, no analysis of the association between cooking fuel and health outcomes, and theoretical or qualitative nature of the studies. This left 122 studies to be included in the systematic review (Supplementary File 1). Descriptive data Across all122 studies a total of 3,728,989 cookstove users were included of which 2,430,194 were unclean cooking fuel users. The main information and findings of included studies are reported in Table 1 and Supplementary File 2. Other health outcomes that are not reported in the tables nor in the metanalysis plots include: respiratory death, tuberculosis, bronchitis, nasal block, nasal discharge, visual impairment, cataract, disorders of sclera, cornea, iris, ciliary body and conjunctiva, glaucoma, hearing loss, burns, headache, liver diseases, kidney diseases, pre/eclampsia, undernutrition, stillbirth, miscarriage, neonatal and perinatal death, birth defects, arthritis, history of falls, back and chronic pain, sarcopenia, sleep problems, breast cancer and influenza like illness. Studies were predominantly carried out in Asia where 78 studies were performed followed by Africa with 22, South and Central America with four each, and North America with two and Europe with one. Eleven studies were multi-countries. Meta-analysis Full results can be found in Table 2 and Figure 2. Using unclean cooking methods compared to using clean cooking methods were positively associated with several comorbidities, including significantly higher odds of digestive disease (OR ¼ 1.37; 95% CI 1.00–1.86; k¼ 5; I2¼99.3%)), respiratory infection (OR ¼ 1.52; 95% CI 1.03–2.26; k¼ 13; I2¼97.4%)), respiratory disease (OR ¼ 1.59; 95% CI 1.28–1.98; k¼ 12; I2¼98.8%)), anemia HEALTH INTERACTIONS 3 https://doi.org/10.1080/29963257.2025.2463654 https://doi.org/10.1080/29963257.2025.2463654 (OR ¼ 1.61; 95% CI 1.32–1.97; k¼ 5; I2¼87.9%)), cognitive impairment (OR ¼ 1.70; 95% CI 1.12–2.57; k¼ 5; I2¼97.5%)), chronic bronchitis (OR ¼ 1.84; 95% CI 1.52–2.22; k¼ 6; I2¼31.8%)), depression (OR ¼ 1.92; 95% CI 1.48–2.48; k¼ 8; I2¼96.6%), chronic cough (OR ¼ 2.23; 95% CI 1.71–2.91; k¼ 18; I2¼67.6%), COPD (OR ¼ 2.37; 1.52–3.69; k¼ 7; I2¼89.7%), and eye irritation (OR ¼ 4.19; 95% CI 1.89–9.29; k¼ 8; I2¼90.0%)). Conversely, using unclean cooking methods compared to using clean cooking methods were associated with lower odds of dyslipidaemia (OR ¼ 0.71; 95% CI 0.51–0.99; k¼ 7; I2¼95.2%) and diabetes (OR ¼ 0.75; 95% CI 0.63–0.90; k¼ 32; I2¼95.0%)). The funnel plots and forest plots for each individual out- come are reported in Supplementary files (Supplementary file 3). No evidence of publication bias was detected, except for respiratory symptoms (Egger’s p¼ 0.004), which yielded a non-significant result in the trim and fill analysis applied. No other comorbidities were significantly associated with cooking methods. Two outcomes (hypertension and diabetes) had enough data to conduct meta-regression. In both outcomes, mean age was not a significant moderator (diabetes OR ¼ 0.81 95% CI 0.62–1.07; hypertension OR¼ 0.96 95% CI 0.79–1.18). Risk of bias The median quality of the studies was 6.3 (range: 4–8), indicating an overall satisfactory quality of the included studies. In particular, while the samples were representative and exposure quite certain, sample size was never justified through specific calculation. Moreover, data were mainly not adjusted for all relevant con- founders. Finally, although the assessment of outcome was quite appropriate, statistical tests were not always fully described. Discussion This systematic review and meta-analysis not only provides a comprehensive synthesis of the effects of unclean cooking on health outcomes but reveals also how unclean cooking is an indicator of socio-economic status. As expected, some symptoms and diseases were clearly associated with indoor pollution and unclean cook- ing fuel use. In particular, eye irritation showed a four-time risk compared to clean cooking, COPD an OR ¼ 2.37, chronic cough a risk more than duplicated, chronic bronchitis an OR ¼ 1.84, respiratory disease an OR ¼ 1.59 and respiratory infection an OR ¼ 1.52. The common mechanism in relation to eye irritation can be explained by the exposure to combustion of unclean fuel and the production of smoke highly irritating to the conjunctiva and mucous membranes (Chan et al., 2021). Whereas associations with other conditions is likely owing to exposure to particulate matter elevating oxidative stress and inflammatory reactions (Deng Figure 1. PRISMA Flow Diagram. 4 D. PIZZOL ET AL. https://doi.org/10.1080/29963257.2025.2463654 https://doi.org/10.1080/29963257.2025.2463654 et al., 2022). Moreover, in many contexts people use plastic materials to facilitate firing and maintenance of cookstoves thus increasing both short- and long-term health issues (Pathak et al., 2024). Interestingly, present results showed significant associations also for diseases usually considered not directly linked to pollution exposure including depression (OR ¼ 1.92), cognitive impairment (OR ¼ 1.70), anemia (OR ¼ 1.61) and digestive disease (OR ¼ 1.37), though these findings are in keeping with air quality as an established risk fac- tor for dementia and depression (Livingston et al., 2020; Zundel et al., 2022). These findings may suggest a multi-factorial pathogenesis including nutritional and socio-economic components and, thus, a strong role of Table 1. Main information of included studies. Study Country Sample size Women % Study Country Sample size Women % Abba, 2022 Albania 20,846 71.28 Kanno, 2021 Ethiopia 10,961 NA Abdo, 2021 Ghana 184 100 Kc, 2023 Nepal 66,400 NA Abdo, 2021 Ghana 211 49.5 Keleb, 2020 Ethiopia 539 NA Adane, 2020 Ethiopia 5,830 48.3 Khan, 2021 Bangladesh 6,543 NA Addis, 2021 Ethiopia 265 49.4 Kim, 2016 China 73,363 100 Admasie, 2018 Ethiopia 1,144 47 Krishnamoorthy, 2018 India 295 52.2 Agrawal, 2012 India 1,98,754 62.6 Li, 2019 China 3,52,743 NA Agrawal, 2014 India 36,127 100 Li, 2021A China 6,997 49.3 Ahmad, 2020 Bangladesh 674 100 Li, 2021B Multi-country 31,371 54.06 Ahmad, 2021 Bangladesh 6,891 48.9 Li, 2023A China 3,404 45.39 Aigbokhaode, 2021 Nigeria 62 100 Li, 2023B China 8,369 54.8 Aigbokhaode, 2021 Nigeria 62 54.8 Liu, 2020 China 9,107 53.5 Akhtar, 2007 Pakistan 3983 100 Liu, 2021 China 2,06,677 100 Akinyemi, 2018 Nigeria 5,445 49.2 Liu, 2022A China 7,449 49.5 Akinyemi, 2018 Nigeria 24,975 49.5 Liu, 2022B China 44,862 58.4 Akinyemi, 2018 Nigeria 28,950 49.9 Liu, 2022C China 6,751 53.9 Albalak, 1999 Bolivia 102 65.3 Liu, 2022D China 2,155 51.9 Albalak, 1999 Bolivia 139 51.8 Liu, 2023 China 5,571 53.67 Alexander, 2017 Nigeria 324 100 Luo, 2020 China 37,870 51.88 Alexander, 2018 Nigeria 324 100 Mbatchou Ngahane, 2015 Cameroon 300 100 Alim, 2013 Bangladesh 420 100 Mishra, 2003 Zimbabwe 3,182 NA Amadu, 2021 Multi-country 37,760 NA Mitra, 2023 India 123 100 Amadu, 2021 Multi-country 93,741 NA Mondal, 2020 India 2,34,606 NA Amadu, 2023 Multi-country 1,02,247 50 Nicolau, 2022 Multi-country 418 100 Amadu, 2023 Multi-country 1,02,247 50 Page, 2015 India 12,782 100 Arku, 2020 Multi-country 31,490 NA Painschab, 2013 Per�u 266 54 Aung, 2018 India 222 100 Parikh, 2020 India 60 100 Banerjee, 2012 India 1,756 100 Pathak, 2019 India 310 100 Barman, 2019 Bangladesh 410 100 Pial, 2020 Bangladesh 510 100 Baumgartner, 2018 China 205 100 Pokhrel, 2013 Nepal 138 100 Behera, 1991 India 1,485 100 Rajkumar, 2018 Honduras 142 100 Benka-Coker, 2022 Honduras 146 100 Regalado, 2006 Mexico 845 100 Cao, 2020 China 6,010 50.8 Roberman, 2021 Nigeria 41,256 100 Cao, 2020 China 8,999 52.9 Romieu, 2009 Mexico 552 100 Chavez-Zacarias, 2022 Per�u 16,043 49.5 Sana, 2019 Burkina Faso 1,705 100 Chair, 2023 China 1,53,484 NA Sanbata, 2014 Ethiopia 346 32.5 Chakraborty, 2018 India 92 100 Shao, 2021 China 8,637 49.3 Chan, 2018 China 1,84,400 NA Sharma, 1998 India 633 51.5 Chan, 2020 China 2,56,343 NA Shayo, 2022 Tanzania 20,224 NA Chan et al., 2021 China 2,60,109 NA Shrestha, 2005 Nepal 168 94 Chen, 2020 China 1,616 72.5 Smith, 2022 A Multi-country 13,559 54.5 Choi, 2014 India 845 47.7 Smith, 2022B Multi-country 14,585 55 Choi, 2014 India 547 100 Tian, 2023 China 4,969 54.7 Clasen, 2022 Multi-country 3,200 100 Vakalopoulos, 2021 Sri Lanka 384 100 Cong, 2021 China 12,490 52.2 Wafula, 2000 Kenya 248 NA Deng, 2020 China 3,754 52.5 Wafula, 2000 Kenya 400 100 Deng et al., 2022A China 4,161 45.4 Walker, 2019 Honduras 150 100 Deng et al., 2022B China 7,807 48 Wang, 2016 China 396 100 Diaz, 2006 Guatemala 456 100 Wang, 2023 Multi-country 12,489 61.3 Du, 2021 China 3,904 48.3 Weber, 2020 Ghana 819 100 Dutta, 2011 India 480 100 Wen, 2023 China 2,55,816 64 Epstein, 2012 India 14,850 100 Wylie, 2015 India 1,369 100 Hu, 2023 China 5,707 46.1 Xu, 2023 China 6,134 49.8 Hussein, 2020 Ghana 1,626 100 Xu, 2023 China 3,413 40.8 Hystad, 2019 Multi-country 91,350 58,9 Xu, 2023 Mexico 6,097 59.1 Islam, 2021 India 93,721 NA Xue, 2022 China 2,593 52.4 Islam, 2022 A Bangladesh 7,334 NA Yan, 2016 China 4,594 53.4 Islam, 2022B India 53,438 53.7 Ye, 2022A India 799 100 Jack, 2021 Ghana 887 100 Ye, 2022B Multi-country 3,002 100 Jang, 2023 China 9,599 50.3 Young, 2018 Honduras 147 100 Ji, 2021 China 5,140 47.8 Younger, 2023 Multi-country 3,195 100 Ji, 2022 China 13,544 51.8 Yu, 2018 China 1,15,625 79.5 Jin, 2022 China 29,789 52.1 Yu, 2020 China 91,166 64.1 Goyal, 2021 India 348 NA Yu, 2022 China 4,523 53.7 Juntarawijit, 2020 Thailand 1,071 84.2 Yu, 2022 China 3,544 57.2 Kanagasabai, 2022 China 753 55.2 Zhang, 2021 China 8,073 100 Kanagasabai, 2023 China 646 56 Zhou, 2014 China 306 NA HEALTH INTERACTIONS 5 social determinants of health. This hypothesis is also supported by the association of unclean cooking fuel use with lower odds of dyslipidaemia (OR ¼ 0.71) and diabetes (OR ¼ 0.75) compared to clean cooking. This may suggest that a higher household threshold allows access not only to a clean cooking method but also to higher and more processed food. As result, we are called to act in paradox settings where double bur- den diseases put to the test fragile and vulnerable health systems with limited resources. Based on these results, the distribution and usage of improved cookstoves should be implemented widely considering health environmental and economic impacts. Indeed, the access to clean cooking technology may reduce associated health symptoms and diseases, improve energy efficiency of combustion with consequent reduction of polluting fuel collection activities and consumption and preserve family financial resources. This latter point is particularly important in context where people are living on less than one dollar per day where small savings represent a high percentage of income. However, provision of cookstoves per se is not enough without basic information and training of beneficiaries. Indeed, the habit to use plastic material for firing and the necessity of multiple stoves would maintain the main health risk factors with limited impact. Therefore, these programs should be supported by training activities to increase sustainability, education and awareness and to increase, in turn, the acceptance and the demand for appropriate cookstove production and distribution. The strengths of this review and meta-analysis are the large number of studies and participants included, the clear results and the consideration of all possible health outcomes. However, these finding should be con- sidered in light of some limitations: (I) the heterogeneity and lack of standard approach for impact evalu- ation, (II) the lack of micro-context consideration (indoor/outdoor cooking place) and use of plastic and toxic material for firing that could impact health and (III) lack of information of exclusivity use of improved cookstove or contemporary use of traditional stoves. Finally, it is possible that there is between country vari- ation in relation to the strength of effects between unclean cooking fuel use and the various health outcomes studied, for example, owing to levels of outdoor air pollution. All together, these limitations lead to Table 2. Association between unclean cooking and comorbidities compared to clean cooking methods. Outcome k studies OR (95% CI) p-value I2 (95% CI) Eggers p-value Anemia 5 1.61 (1.32–1.97) <0.001 87.9 (74.2–94.3) NA Asthma 12 0.92 (0.50–1.70) 0.80 78.4 (62.7–87.5) 0.77 Born underweight 6 1.01 (0.70–1.45) 0.963 95.9 (93.3–97.5) NA Chronic bronchitis 6 1.84 (1.52–2.22) <0.001 31.8 (0.0–72.4) NA Chronic cough 18 2.23 (1.71–2.91) <0.001 67.6 (47.1–80.2) 0.23 Cog impairment 5 1.70 (1.12–2.57) 0.012 97.5 (96.0–98.5) NA COPD 7 2.37 (1.52–3.69) <0.001 89.7 (81.4–94.3) NA CVD 21 0.94 (0.70–1.26) 0.683 99.2 (99.1–99.3) 0.41 CVD cerebrovascular 12 1.28 (0.80–2.05) 0.313 96.1 (94.5–97.2) 0.99 Depression 8 1.92 (1.48–2.48) <0.001 96.6 (94.9–97.7) NA Diabetes 32 0.75 (0.63–0.90) 0.002 95.0 (93.8–95.9) 0.63 Digestive disease 5 1.37 (1.00–1.86) 0.049 99.3 (99.0–99.5) NA Dyslipidaemia 7 0.71 (0.51–0.99) 0.046 95.2 (92.2–97.0) NA Eye irritation 8 4.19 (1.89–9.29) <0.001 90.0 (82.7–94.2) NA Hypertension 37 1.03 (0.84–1.26) 0.767 97.8% (97.4–98.1) 0.80 Preterm delivery 5 1.09 (0.88–1.35) 0.435 0.0 (0.0–79.2) NA Respiratory disease 12 1.59 (1.28–1.98) <0.001 98.8 (98.4–99.0) 0.87 Resp infection 13 1.52 (1.03–2.26) 0.036 97.4 (96.5–98.0) 0.65 Respiratory symptoms� 14 1.20 (0.79; 1.83) 0.401 93.3 (91.0–95.0) 0.004� �Effect size for respiratory symptoms are from the updated Trim and Fill analysis, conducted due to significant publication bias. 6 D. PIZZOL ET AL. variability and inconsistency of ORs for specific disease from different studies or population. However, this is beyond the scope of the present manuscript and thus a topic of future investigation. In conclusion, the present work represents a clear picture on the state of art on clean and unclean cooking methods that highlight the multiple health, environmental and economic advantages of clean cooking promo- tion. The findings suggest an urgent need to encourage, promote and support integrated programs to reduce unclean cooking fuel use by supporting the implementation of appropriate cookstoves in combination with education, information and training activities aimed to facilitate a correct use of the device. In particular, based on the main ‘theory of change’, Governments should activate and foster ambitious clean cooking tran- sitions, clean cooking markets should be thriving, diverse, competitive, and are serving users. Moreover, the ecosystem should be collaborative, resilient, and supportive of continued sector advancement (Clean Cooking Alliance). Our findings provide support for adoption of the United Nations Sustainable Development Goal (SDG) 7 ‘ensure access to affordable, reliable, sustainable and modern energy for all’ (United Nations, 2021). Authors’ contributions All authors listed (Damiano Pizzol, Mike Trott, Dong Keon Yon, Masoud Rahmati, Jae Il Shin, Barbara Kamholz, Biraj Karmacharya, Prabha Shrestha, Benjamin R Underwood, Laurie Butler, Yvonne Barnett, Nicola Veronese, Pinar Soysal, Guillermo Gomez, Simone Mortara, Eugenio Malfatti, Sanjiv Ahluwalia, Alice Concari, Alice Corinaldi, Tatiana Marrufo, Filippo Uberti, Guillermo F. L�opez S�anchez, Lee Smith) have made a substantial, direct and intellectual contribution to the work, and approved it for publication. Disclosure statement No potential conflict of interest was reported by the author(s). ORCID Guillermo F. L�opez S�anchez http://orcid.org/0000-0002-9897-5273 Data availability statement The data that support the findings of this study are available from the corresponding author upon reasonable request. 0.10 1.00 10.00 Dyslipidaemia* Diabetes* Asthma CVD cerebrovascular Born underweight Hypertension Preterm delivery Respiratory symptoms CVD cerebrovascular Digestive disease* Resp infection* Respiratory disease* Anaemia* Cog impairment* Chronic bronchitis* Depression* Chronic cough* COPD* Eye irritation* Favours not-clean Favours clean Figure 2. Meta-analysis findings: Cooking method and health outcomes. HEALTH INTERACTIONS 7 References Balduzzi, S., R€ucker, G., & Schwarzer, G. (2019). How to perform a meta-analysis with R: A practical tutorial. Evidence- Based Mental Health, 22(4), 153–160. https://doi.org/10.1136/ebmental-2019-300117 Chan, K. H., Yan, M., Bennett, D. A., Guo, Y., Chen, Y., Yang, L., Lv, J., Yu, C., Pei, P., Lu, Y., Li, L., Du, H., Lam, K. B. 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PIZZOL ET AL. https://doi.org/10.1136/ebmental-2019-300117 https://doi.org/10.1371/journal.pmed.1003716 https://doi.org/10.1371/journal.pmed.1003716 https://doi.org/10.1016/j.scitotenv.2021.152256 https://doi.org/10.1136/bmj.39489.470347.AD https://doi.org/10.1016/S0140-6736(20)30367-6 https://doi.org/10.1016/j.jpsychires.2023.11.025 https://doi.org/10.1016/j.jpsychires.2023.11.025 https://doi.org/10.5334/aogh.4232 https://www.r-project.org/ https://doi.org/10.1001/jama.283.15.2008 https://doi.org/10.1016/j.spc.2021.06.005 https://sdgs.un.org/goals/goal7 https://sdgs.un.org/goals/goal7 https://www.who.int/news/item/20-01-2022-who-publishes-new-global-data-on-the-use-of-clean-and-polluting-fuels-for-cooking-by-fuel-type https://www.who.int/news/item/20-01-2022-who-publishes-new-global-data-on-the-use-of-clean-and-polluting-fuels-for-cooking-by-fuel-type https://doi.org/10.1186/s13195-023-01254-1 https://doi.org/10.1186/s13195-023-01254-1 https://doi.org/10.1016/j.neuro.2022.10.011 https://doi.org/10.1016/j.neuro.2022.10.011 Unclean cooking fuel use and all health outcomes, a systematic review and meta-analysis Abstract Background Methods Search strategy Type of studies, inclusion, and exclusion criteria Data extraction Assessment of study quality Statistical analysis Results Literature search Descriptive data Meta-analysis Risk of bias Discussion Authors’ contributions Disclosure statement Orcid Data availability statement References