Wiley Interdisciplinary Reviews: Climate Change
FOCUS ARTICLE OPEN ACCESS
The Rapid Progress of Climate Change Requires Effective
Concepts for Protecting People Indoors
Tunga Salthammer1,2 | Lidia Morawska2,3
1Department of Material Analysis and Indoor Chemistry, Fraunhofer WKI, Braunschweig, Germany | 2International Laboratory for Air Quality and
Health, Queensland University of Technology, Brisbane, Queensland, Australia | 3Global Centre for Clean Air Research (GCARE), School of Sustainability,
Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, UK
Correspondence: Tunga Salthammer ()
Received: 20 February 2025 | Revised: 9 December 2025 | Accepted: 24 January 2026
Editor-in-Chief: Daniel Friess | Domain Editor: Timothy R. Carter
Keywords: building design | heat stress | indoor environment | indoor pollutants | protective measures
ABSTRACT
According to the latest forecasts from the United Nations, it is highly likely that we will miss by a wide margin the 1.5°C climate
target set in the Paris Agreement in 2015. Rather, this planet has to prepare for a global temperature increase of 2.7°C or higher
relative to pre-industrial times by 2100, which will be associated with increases in the frequency of many types of hazardous
weather that affect society. Buildings, in which much of everyday life takes place in industrialized countries, must consequently
be designed and equipped to meet future requirements in order to ensure the health of the population in the short and long-term.
Occupied indoor spaces serve not only as living and working environments but are also necessary to protect people, especially
vulnerable population groups, from heat stress, microbial contamination, air pollutants, and other threats. The structural and
technical possibilities for this exist, but implementation often fails due to lack of insight and administrative hurdles. Although
the needs are obvious, this aspect of climate change has not yet been adequately addressed at either the national or sub-national
level. As climate change progresses, a lack of structural measures and inadequate crisis management will inevitably lead to fur-
ther fatal problems in weather-related events. It is therefore necessary to place greater emphasis on the importance of the indoor
environment in the context of climate change. Key issues for solutions aimed at improving indoor conditions must include ther-
mal comfort, ventilation, and the reduction of air pollutants.
This article is categorized under:
Assessing Impacts of Climate Change > Evaluating Future Impacts of Climate Change
Climate and Development > Sustainability and Human Well-Being
Policy and Governance > Governing Climate Change in Communities, Cities, and Regions
1 | Introduction Global greenhouse gas emissions continue to rise (United
Nations Environment Programme 2024), pushing the world to-
The effects of climate change are increasingly evident in both ward a global temperature increase of at least 2.7°C or higher
natural systems and human society, while at the same time by the end of this century (Intergovernmental Panel on Climate
limiting the rise in global temperatures to 1.5°C above prein- Change 2021). Given these realities, it is clear that the global
dustrial levels (United Nations 2016), as written down in the community must also consider a future, where the 1.5°C target
Paris Agreement (COP21), is becoming increasingly unlikely. may not be met. Recent climate models suggest that occurrences
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium,
provided the original work is properly cited.
© 2026 The Author(s). WIREs Climate Change published by Wiley Periodicals LLC.
Wiley Interdisciplinary Reviews: Climate Change, 2026; 17:e70043 1 of 11
https://doi.org/10.1002/wcc.70043
, 17577799, 2026, 1, Downloaded from https://wires.onlinelibrary.wiley.com/doi/10.1002/wcc.70043 by INASP/HINARI - PAKISTAN, Wiley Online Library on [30/03/2026]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License
of extreme heat in several regions of the world will increase Although there is now sufficient scientific expertise to realis-
significantly and faster than previously projected (Kornhuber tically assess the current and future consequences of climate
et al. 2024). Despite the uncertainties in the scenarios and mod- change for human society in the indoor environment, the signif-
els, it is nonetheless imperative to prepare society for the possi- icance of this fact is not yet fully understood.
ble consequences.
In this focus article, Section 2 describes four distinct ways in
However, indoor spaces, where people spend most of the day and which indoor air quality can be affected by changing climate and
where they seek refuge from rain, heat, and strong winds, are associated environmental conditions: thermal comfort, particu-
significantly underrepresented in the overall number of publica- late matter, air chemistry and microbiological contamination.
tions on climate change. The 2001 report of Working Group II of Section 3 summarizes how a combination of building design
the Intergovernmental Panel on Climate Change (2001) makes and monitoring can enhance air quality through ventilation,
rudimentary reference to indoor air quality, but primarily to Section 4 outlines the types of measures required to prepare the
pollutants. The 2007 Working Group II report briefly refers to building environment for changing climate and Section 5 offers
indoor heat and thermal comfort (Intergovernmental Panel on concluding remarks. Our supporting literature review followed
Climate Change 2007). Only the 2022 Working Group II report the PRISMA methodology (Page et al. 2021).
states that there is an emerging risk of diminished indoor ther-
mal comfort due to climate change (Intergovernmental Panel on
Climate Change 2022). 2 | Impact of Extreme Weather Conditions on
Indoor Air Quality
A pivotal indoor-focused review by the Institute of Medicine
(IOM) (2011) marked a turning point in recognizing indoor We are currently not only failing to reduce greenhouse gas
environments in climate change discourse. The committee emissions, but are also largely ignoring the necessary mea-
concluded that changes in indoor air quality caused by climate sures to protect people from the negative economic (Semieniuk
change represent an important public health problem that de- et al. 2022) and health (Ofremu et al. 2025) impacts of climate
serves attention and action. In his review on climate change ad- change. Extreme weather events affect human safety and
aptation through personal indoor and outdoor thermal comfort comfort in the indoor environment. Heat-related health haz-
management, Hitchings (2011) pointed out that aspects other ards, habitat destruction with effects on social and economic
than temperature should also be considered. In the following infrastructure, as well as other threats and consequences re-
years, publications occasionally appeared addressing the possi- sulting from delayed action are convincingly demonstrated by
ble effects of climate change on indoor air quality (Fisk 2015; Romanello et al. (2024). However, their publication does not ex-
Gherasim et al. 2024; Mansouri et al. 2022; Nazaroff 2013; plicitly address the impacts of climate change on indoor spaces,
Spengler 2012; Tham 2016; Vardoulakis et al. 2015). These re- so the indoor-related factors and parameters that essentially in-
ports clearly identified the potential future hazards to human fluence indoor thermal comfort and air quality (IAQ) are sum-
health if no mitigation and adaptation measures are taken. marized in Figure 1.
Despite these findings, the slow progress in adaptive building It is immediately apparent that indoor conditions are deter-
strategies for future requirements is surprising. The adverse mined by a complex interplay of outdoor conditions, building
impacts of extreme weather events have long been known, in physics, ventilation, heating and cooling, indoor design, chemi-
Europe at least since the heatwave of 2003 (Fischer et al. 2004; cal reactions, and lifestyle habits. Although an essential goal for
Schär and Jendritzky 2004; Steul et al. 2018). As a consequence protecting residents is to avoid indoor heat stress, uncontrolled
of these events, the World Health Organization (2021a) has pub- cooling is also detrimental to human health and comfort. If the
lished recommendations for the prevention of heat stress indoors temperature is lowered indoors, attention must always be paid
and outdoors. Extreme weather events with heat, heavy rain, to the humidity to avoid dew point effects (Hens 2017) and mold
sandstorms, wildfires, and smog events are occurring more fre- growth. Acceptable indoor air quality can therefore only be
quently and with greater intensity (Merdji et al. 2023; Morawska achieved by taking several control variables into account.
et al. 2021; Wasko et al. 2021). There are numerous publications
on the negative health effects of climate change, but mostly with
reference to heat and air pollution (Alahmad et al. 2023; Ebi 2.1 | Thermal Comfort and Discomfort
et al. 2021). The influence of humidity is less frequently reported
(Papanastasiou et al. 2015), and exposure to allergens related to For human thermal comfort, the operative temperature Top
mold and dampness has also received little attention (Eguiluz- is important. Top (°C) is calculated for low air velocities from
Gracia et al. 2020). However, today it is scientifically accepted the mean value of air temperature Tair (°C) and the mean ra-
that the overall system of outdoor environment—building en- diant temperature Tmrt (°C) with Top = (Tair + Tmrt)/2 (ISO/FDIS
velope—indoor environment must be considered in order to 7726 2025). Tmrt is essentially determined by the average radiant
describe the living conditions indoors (Pallubinsky et al. 2023). temperature of walls, floor, and ceiling. Outdoors, solar radia-
The heat and mass transfer between the outdoor and indoor en- tion contributes the most to Tmrt. It is also important to realize
vironment is taken into account for example by a holistic model that temperature is not the same as heat.
for long-term predictions of thermal comfort and exposure to
pollutants indoors (Salthammer et al. 2022; Zhao et al. 2025, The action plans available today mostly deal with protection
2024). Singh et al. (2024) also see an urgent need to strengthen from high temperatures. But this is an incomplete approach,
heat risk management efforts. because the transfer of heat to the human body is crucial. If
2 of 11 Wiley Interdisciplinary Reviews: Climate Change, 2026
FOCUS ARTICLE OPEN ACCESS
The Rapid Progress of Climate Change Requires Effective
Concepts for Protecting People Indoors
Tunga Salthammer1,2 | Lidia Morawska2,3
1Department of Material Analysis and Indoor Chemistry, Fraunhofer WKI, Braunschweig, Germany | 2International Laboratory for Air Quality and
Health, Queensland University of Technology, Brisbane, Queensland, Australia | 3Global Centre for Clean Air Research (GCARE), School of Sustainability,
Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, UK
Correspondence: Tunga Salthammer ()
Received: 20 February 2025 | Revised: 9 December 2025 | Accepted: 24 January 2026
Editor-in-Chief: Daniel Friess | Domain Editor: Timothy R. Carter
Keywords: building design | heat stress | indoor environment | indoor pollutants | protective measures
ABSTRACT
According to the latest forecasts from the United Nations, it is highly likely that we will miss by a wide margin the 1.5°C climate
target set in the Paris Agreement in 2015. Rather, this planet has to prepare for a global temperature increase of 2.7°C or higher
relative to pre-industrial times by 2100, which will be associated with increases in the frequency of many types of hazardous
weather that affect society. Buildings, in which much of everyday life takes place in industrialized countries, must consequently
be designed and equipped to meet future requirements in order to ensure the health of the population in the short and long-term.
Occupied indoor spaces serve not only as living and working environments but are also necessary to protect people, especially
vulnerable population groups, from heat stress, microbial contamination, air pollutants, and other threats. The structural and
technical possibilities for this exist, but implementation often fails due to lack of insight and administrative hurdles. Although
the needs are obvious, this aspect of climate change has not yet been adequately addressed at either the national or sub-national
level. As climate change progresses, a lack of structural measures and inadequate crisis management will inevitably lead to fur-
ther fatal problems in weather-related events. It is therefore necessary to place greater emphasis on the importance of the indoor
environment in the context of climate change. Key issues for solutions aimed at improving indoor conditions must include ther-
mal comfort, ventilation, and the reduction of air pollutants.
This article is categorized under:
Assessing Impacts of Climate Change > Evaluating Future Impacts of Climate Change
Climate and Development > Sustainability and Human Well-Being
Policy and Governance > Governing Climate Change in Communities, Cities, and Regions
1 | Introduction Global greenhouse gas emissions continue to rise (United
Nations Environment Programme 2024), pushing the world to-
The effects of climate change are increasingly evident in both ward a global temperature increase of at least 2.7°C or higher
natural systems and human society, while at the same time by the end of this century (Intergovernmental Panel on Climate
limiting the rise in global temperatures to 1.5°C above prein- Change 2021). Given these realities, it is clear that the global
dustrial levels (United Nations 2016), as written down in the community must also consider a future, where the 1.5°C target
Paris Agreement (COP21), is becoming increasingly unlikely. may not be met. Recent climate models suggest that occurrences
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium,
provided the original work is properly cited.
© 2026 The Author(s). WIREs Climate Change published by Wiley Periodicals LLC.
Wiley Interdisciplinary Reviews: Climate Change, 2026; 17:e70043 1 of 11
https://doi.org/10.1002/wcc.70043
, 17577799, 2026, 1, Downloaded from https://wires.onlinelibrary.wiley.com/doi/10.1002/wcc.70043 by INASP/HINARI - PAKISTAN, Wiley Online Library on [30/03/2026]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License
of extreme heat in several regions of the world will increase Although there is now sufficient scientific expertise to realis-
significantly and faster than previously projected (Kornhuber tically assess the current and future consequences of climate
et al. 2024). Despite the uncertainties in the scenarios and mod- change for human society in the indoor environment, the signif-
els, it is nonetheless imperative to prepare society for the possi- icance of this fact is not yet fully understood.
ble consequences.
In this focus article, Section 2 describes four distinct ways in
However, indoor spaces, where people spend most of the day and which indoor air quality can be affected by changing climate and
where they seek refuge from rain, heat, and strong winds, are associated environmental conditions: thermal comfort, particu-
significantly underrepresented in the overall number of publica- late matter, air chemistry and microbiological contamination.
tions on climate change. The 2001 report of Working Group II of Section 3 summarizes how a combination of building design
the Intergovernmental Panel on Climate Change (2001) makes and monitoring can enhance air quality through ventilation,
rudimentary reference to indoor air quality, but primarily to Section 4 outlines the types of measures required to prepare the
pollutants. The 2007 Working Group II report briefly refers to building environment for changing climate and Section 5 offers
indoor heat and thermal comfort (Intergovernmental Panel on concluding remarks. Our supporting literature review followed
Climate Change 2007). Only the 2022 Working Group II report the PRISMA methodology (Page et al. 2021).
states that there is an emerging risk of diminished indoor ther-
mal comfort due to climate change (Intergovernmental Panel on
Climate Change 2022). 2 | Impact of Extreme Weather Conditions on
Indoor Air Quality
A pivotal indoor-focused review by the Institute of Medicine
(IOM) (2011) marked a turning point in recognizing indoor We are currently not only failing to reduce greenhouse gas
environments in climate change discourse. The committee emissions, but are also largely ignoring the necessary mea-
concluded that changes in indoor air quality caused by climate sures to protect people from the negative economic (Semieniuk
change represent an important public health problem that de- et al. 2022) and health (Ofremu et al. 2025) impacts of climate
serves attention and action. In his review on climate change ad- change. Extreme weather events affect human safety and
aptation through personal indoor and outdoor thermal comfort comfort in the indoor environment. Heat-related health haz-
management, Hitchings (2011) pointed out that aspects other ards, habitat destruction with effects on social and economic
than temperature should also be considered. In the following infrastructure, as well as other threats and consequences re-
years, publications occasionally appeared addressing the possi- sulting from delayed action are convincingly demonstrated by
ble effects of climate change on indoor air quality (Fisk 2015; Romanello et al. (2024). However, their publication does not ex-
Gherasim et al. 2024; Mansouri et al. 2022; Nazaroff 2013; plicitly address the impacts of climate change on indoor spaces,
Spengler 2012; Tham 2016; Vardoulakis et al. 2015). These re- so the indoor-related factors and parameters that essentially in-
ports clearly identified the potential future hazards to human fluence indoor thermal comfort and air quality (IAQ) are sum-
health if no mitigation and adaptation measures are taken. marized in Figure 1.
Despite these findings, the slow progress in adaptive building It is immediately apparent that indoor conditions are deter-
strategies for future requirements is surprising. The adverse mined by a complex interplay of outdoor conditions, building
impacts of extreme weather events have long been known, in physics, ventilation, heating and cooling, indoor design, chemi-
Europe at least since the heatwave of 2003 (Fischer et al. 2004; cal reactions, and lifestyle habits. Although an essential goal for
Schär and Jendritzky 2004; Steul et al. 2018). As a consequence protecting residents is to avoid indoor heat stress, uncontrolled
of these events, the World Health Organization (2021a) has pub- cooling is also detrimental to human health and comfort. If the
lished recommendations for the prevention of heat stress indoors temperature is lowered indoors, attention must always be paid
and outdoors. Extreme weather events with heat, heavy rain, to the humidity to avoid dew point effects (Hens 2017) and mold
sandstorms, wildfires, and smog events are occurring more fre- growth. Acceptable indoor air quality can therefore only be
quently and with greater intensity (Merdji et al. 2023; Morawska achieved by taking several control variables into account.
et al. 2021; Wasko et al. 2021). There are numerous publications
on the negative health effects of climate change, but mostly with
reference to heat and air pollution (Alahmad et al. 2023; Ebi 2.1 | Thermal Comfort and Discomfort
et al. 2021). The influence of humidity is less frequently reported
(Papanastasiou et al. 2015), and exposure to allergens related to For human thermal comfort, the operative temperature Top
mold and dampness has also received little attention (Eguiluz- is important. Top (°C) is calculated for low air velocities from
Gracia et al. 2020). However, today it is scientifically accepted the mean value of air temperature Tair (°C) and the mean ra-
that the overall system of outdoor environment—building en- diant temperature Tmrt (°C) with Top = (Tair + Tmrt)/2 (ISO/FDIS
velope—indoor environment must be considered in order to 7726 2025). Tmrt is essentially determined by the average radiant
describe the living conditions indoors (Pallubinsky et al. 2023). temperature of walls, floor, and ceiling. Outdoors, solar radia-
The heat and mass transfer between the outdoor and indoor en- tion contributes the most to Tmrt. It is also important to realize
vironment is taken into account for example by a holistic model that temperature is not the same as heat.
for long-term predictions of thermal comfort and exposure to
pollutants indoors (Salthammer et al. 2022; Zhao et al. 2025, The action plans available today mostly deal with protection
2024). Singh et al. (2024) also see an urgent need to strengthen from high temperatures. But this is an incomplete approach,
heat risk management efforts. because the transfer of heat to the human body is crucial. If
2 of 11 Wiley Interdisciplinary Reviews: Climate Change, 2026
