This study investigated the thermal comfort effects of surgical and N95 masks in a summer air-conditioned environment (23.0–28.0°C) using a three-stage experimental design with 24 sedentary subjects. Physiological and subjective responses were measured during adaptation (Stage I), mask-wearing (Stage II) and post-removal (Stage III). Results showed that mask-wearing could significantly increase facial skin temperature in Stage II, leading to warm and humid discomfort, whereas facial thermal conditions recovered rapidly after mask removal and in slightly warm environments (28.0°C), comfort levels exceeded those in the adaptation stage, indicating thermal adaptation. Core temperature and heart rate remained stable throughout, confirming that mask-related discomfort was primarily localized. Compared with surgical masks, N95 masks consistently resulted in lower thermal acceptability, with differences of up to 9.0%. Thermal analysis revealed that the overall neutral temperature increased from Stage I to Stage III, while the preferred temperature remained consistently lower than the neutral temperature. During mask-wearing, the acceptable facial temperature range shifted towards cooler conditions and expanded after mask removal, indicating enhanced thermal tolerance. Based on these findings, a facial thermal comfort prediction model was developed using nasal and chin skin temperatures, providing quantitative support for thermal comfort management and mask selection in summer air-conditioned environments.
WattsNAmannMArnellNAyeb-KarlssonSBeagleyJBelesovaKBoykoffMByassPCaiWCampbell-LendrumDCapstickSChambersJColemanSDalinCDalyMDasandiNDasguptaSDaviesMDi NapoliCDominguez-SalasPDrummondPDubrowREbiKEckelmanMEkinsPEscobarLEGeorgessonLGolderSGraceDGrahamHHaggartPHamiltonIHartingerSHessJHsuS-CHughesNJankin MikhailovSJimenezMPKelmanIKennardHKiesewetterGKinneyPLKjellstromTKnivetonDLampardPLemkeBLiuYLiuZLottMLoweRMartinez-UrtazaJMaslinMMcAllisterLMcGushinAMcMichaelCMilnerJMoradi-LakehMMorrisseyKMunzertSMurrayKANevilleTNilssonMOdhiambo SeweMOreszczynTOttoMOwfiFPearmanOPencheonDQuinnRRabbanihaMRobinsonERocklövJRomanelloMSemenzaJCShermanJShiLSpringmannMTabatabaeiMTaylorJTrifanesJShumake-GuillemotJVuBWilkinsonPWinningMGongPMontgomeryHCostelloA. The 2020 report of the Lancet countdown on health and climate change: responding to converging crises. Lancet2020; 397: 129–170.
2.
XieZXQinYCLiYShenWZhengZCLiuSR. Spatial and temporal differentiation of COVID-19 epidemic spread in mainland China and its influencing factors. Sci Total Environ2020; 744: 140929.
3.
MooreJOffitP. SARS-CoV-2 vaccines and the growing threat of viral variants. JAMA2021; 325: 821–822.
4.
HuiDSChowBKChuLNgSSLeeNGinTChanMT. Exhaled air dispersion during coughing with and without wearing a surgical or N95 mask. PLoS One2012; 7: e50845.
5.
ShakyaKMNoyesAKallinRPeltierRE. Evaluating the efficacy of cloth facemasks in reducing particulate matter exposure. J Expo Sci Environ Epidemiol2017; 27: 352–357.
6.
Zender-ŚwierczETelejkoMGaliszewskaB. Influence of masks protecting against SARS-CoV-2 on thermal comfort. Energies2021; 14: 3315.
7.
NielsenRBerglundLGGwosdowARDuBoisAB. Thermal sensation of the body as influenced by the thermal microclimate in a face mask. Ergonomics1987; 30: 1689–1703.
8.
HayashiCTokuraH. The effects of two kinds of mask (with or without exhaust valve) on clothing microclimates inside the mask in participants wearing protective clothing for spraying pesticides. Int Arch Occup Environ Health2004; 77: 73–78.
9.
RobergeRJKimJHBensonSM. Absence of consequential changes in physiological, thermal and subjective responses from wearing a surgical mask. Respir Physiol Neurobiol2012; 181: 29–35.
10.
ZhangRHLiuJHZhangLLinJWuQQ. The distorted power of medical surgical masks for changing the human thermal psychology of indoor personnel in summer. Indoor Air2021; 31: 1645–1656.
11.
LinYCChenCP. Thermoregulation and thermal sensation in response to wearing tight-fitting respirators and exercising in hot-and-humid indoor environment. Build Environ2019; 160: 106158.
12.
HuRLiuJLXieYHSuYFangZSDiaoYFShenHG. Influencing assessment of mask wearing on thermal comfort and pleasure during outdoor walking in hot summer region. Urban Clim2024; 54: 101854.
13.
ZhuHWangHQLiuZQKouGXLiCLiDR. Experimental study on the variations in human skin temperature under simulated weightlessness. Build Environ2017; 117: 135–145.
14.
LiuCLiGJHeYHZhangZXDingYJ. Effects of wearing masks on human health and comfort during the COVID-19 pandemic. IOP Conf Ser Earth Environ Sci2020; 531: 012034.
15.
RusdaniajiDDharmastitiR. Effect of wearing different types of face mask to heat strain during physical activities. J Syst Teknik Ind2021; 23: 178–189.
16.
LiYTokuraHGuoYPWongASWongTChungJNewtonE. Effects of wearing N95 and surgical facemasks on heart rate, thermal stress and subjective sensations. Int Arch Occup Environ Health2005; 78: 501–509.
17.
WangLJZuoGDZhangMM. Impact of face masks on human thermal response in indoor environments. J Xi'an Polytech Univ2021; 35: 39–45. In Chinese.
18.
KimJHBensonSMRobergeRJ. Pulmonary and heart rate responses to wearing N95 filtering facepiece respirators. Am J Infect Control2013; 41: 24–27.
19.
IslamSRPrustyDMaitiMDuttaRChattopadhyayPMannaSK. Effect of short-term use of FFP2 (N95) masks on the salivary metabolome of young healthy volunteers: a pilot study. Mol Omics2023; 19: 383–394.
20.
ZhengZPoonETWanKWDaiZHWongSH. Effects of wearing a mask during exercise on physiological and psychological outcomes in healthy individuals: a systematic review and meta-analysis. Sports Med2023; 53: 125–150.
21.
FukushimaAManabeYKosakaYAkagiS. Sustained exercise load by young adult females while wearing surgical mask raises core body temperature measured with zero-heat-flux thermometer. Int J Biometeorol2023; 67: 1345–1352.
22.
ZhuHWangYFWangYCSuHYuCW. Cognitive performance in the heat: a prediction with heart rate variability (HRV) time-domain indices. Indoor Built Environ2025; 34: 319–329.
23.
LinJWLiangYYangYRXieYXZhangHNiuJL. Thermal sensation and comfort models for non-uniform and transient environments, Part V: enhancements of whole-body sensation model. Build Environ2025; 285: 113562.
24.
LiangLFGuoSJSuXWangYKLongZW. PMV Modification model for low-pressure and non-uniform indoor environment. Appl Therm Eng2025; 270: 126266.
25.
HeYDLiNPZhangWJPengJQ. Overall and local thermal sensation & comfort in air-conditioned dormitory with hot-humid climate. Build Environ2016; 101: 102–109.
26.
PellerinNDeschuyteneerACandasV. Local thermal unpleasantness and discomfort prediction in the vicinity of thermoneutrality. Eur J Appl Physiol2004; 92: 717–720.
27.
ParkSHellwigRYGrünGHolmA. Local and overall thermal comfort in an aircraft cabin and their interrelations. Build Environ2021; 46: 1056–1064.
28.
ZhouZQDongL. Experimental investigation of the effect of surgical masks on outdoor thermal comfort in Xiamen, China. Build Environ2023; 229: 109893.
29.
DriverSReynoldsMBrownKVingrenJLHillDWBennettMGillilandTMcShanECallenderLReynoldsEBorundaNMosolfJCatesCJonesA. Effects of wearing a cloth face mask on performance, physiological and perceptual responses during a graded treadmill running exercise test. Br J Sports Med2002; 56: 107–113.
30.
ChenWBMaoYDLuJXLiuJLFangZXZhengZM. A preliminary investigation of the effect of wearing a mask on human thermal comfort. Refrigeration2022; 41: 41–46. In Chinese.
31.
TangTWZhuYCZhouXQGuoZSMaoYDJiangHLFangZSZhengZMChenXH. Investigation of the effects of face masks on thermal comfort in Guangzhou, China. Build Environ2022; 214: 108932.
32.
LinYCWeiHCChenCP. Thermoregulation and subjective thermal perception of N95 respirator users: influence of significant workloads. Build Environ2023; 228: 109874.
33.
LangXYVasquezNGLiuWWWyonDPWargockiP. Effects of wearing masks indoors on the cognitive performance and physiological and subjective responses of healthy young adults. Build Environ2024; 252: 111248.
34.
HuaWZuoYWanRYXiongLDTangTZouLShuXHLiL. Short-term skin reactions following use of N95 respirators and medical masks. Contact Dermatitis2020; 83: 115–121.
35.
ScaranoAInchingoloFLorussoF. Facial skin temperature and discomfort when wearing protective face masks: thermal infrared imaging evaluation and hands moving the mask. Int J Environ Res Public Health2020; 17: 4624.
36.
GuCJLiYNianXHZhengYGHongB. Effects of masks on physiological and thermal responses of college students during outdoor activities. Urban Clim2023; 52: 101720.
37.
LangXYLiuWWWyonDPWargockiP. Wearing a mask reduces cognitive performance at neutral temperatures: evidence from climate chamber experiments on heat acclimatized subjects in China. Build Environ2025; 277: 112949.
38.
ZhongQLSongJYShiDCDungCH. Protective facemask-induced facial thermal stress and breathing burden during exercise in gyms. Build Environ2023; 244: 110840.
39.
ZhengZMDaiKQZhouXQLiuJLLiuWWLuJLFangZS. Field investigation of thermal comfort with face masks in outdoor spaces in South China: a case study. Urban Clim2023; 51: 101632.
40.
ANSI/ASHRAE Standard 55–2017: Thermal environmental conditions for human occupancy American Society of Heating refrigerating and air-conditioning engineers. Atlanta: ASHRAE, 2017.
41.
GB/T 18883-2002. Indoor air quality standard. Beijing: Standardization Administration of the People's Republic of China (SAC), 2002, In Chinese.
42.
ISO 7730 2005. Ergonomics of the thermal environment – Analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria. Geneva: ISO, 2005.
43.
WuYXZhangZXLiuHLiBZChenBFKosonenRJokisaloJ. Age differences in thermal comfort and physiological responses in thermal environments with temperature ramp. Build Environ2023; 228: 109887.
44.
ZhuYX. Building environment studies. Beijing: China Architecture and Building Press, 2016, In Chinese.
45.
NiuJQHongBGengYBMiJYHeJY. Summertime physiological and thermal responses among activity levels in campus outdoor spaces in a humid subtropical city. Sci Total Environ2020; 728: 138757.
46.
WuYXZhangSLiuHChengYLiaoCH. Thermal sensation, sick building syndrome symptoms, and physiological responses of occupants in environments with vertical air temperature differences. J Therm Biol2022; 108: 103276.
47.
FaulFErdfelderELangAGBuchnerA. G*Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behav Res Methods2007; 39: 175–191.
48.
CohenJ.Statistical power analysis for the behavioral sciences. Abingdon-on-Thames, Oxfordshire: Routledge, 2013.
49.
LanLLianZW. Application of statistical power analysis–How to determine the right sample size in human health, comfort and productivity research. Build Environ2010; 45: 1202–1213.
50.
KongDYLiuHWuYXLiBZWeiSYuanMY. Effects of indoor humidity on building occupants’ thermal comfort and evidence in terms of climate adaptation. Build Environ2019; 155: 298–307.
51.
ZhangSLinZ. Review and prospect on advanced ventilation strategies for liveable and sustainable buildings. Build Environ2026; 289: 114122.
52.
WangXYangLGaoSZhaoSKZhaiYC. Thermal comfort in naturally ventilated university classrooms: a seasonal field study in Xi'an, China. Energy Build2021; 247: 111126.
53.
TianXZhangSLinZLiYCChengYLiaoCH. Experimental investigation of thermal comfort with stratum ventilation using a pulsating air supply. Build Environ2019; 165: 106416.
54.
RamanathanNL. A new weighting system for mean surface temperature of the human body. J Appl Physiol1964; 19: 531–533.
55.
FilingeriDFournetDHodderSHavenithG. Tactile cues significantly modulate the perception of sweat-induced skin wetness independently of the level of physical skin wetness. J Neurophysiol2015; 113: 3462–3473.
56.
LuoMHCaoBDamiensJLinBRZhuYX. Evaluating thermal comfort in mixed-mode buildings: a field study in a subtropical climate. Build Environ2015; 88: 46–54.
57.
DhakaSMathurJ. Quantification of thermal adaptation in air-conditioned buildings of composite climate, India. Build Environ2017; 112: 296–307.
58.
JiWJZhuYXCaoB. Development of the predicted thermal sensation (PTS) model using the ASHRAE global thermal comfort database. Energy Build2020; 211: 109780.
59.
GaoJWangYWargockiP. Comparative analysis of modified PMV models and SET models to predict human thermal sensation in naturally ventilated buildings. Build Environ2015; 92: 200–208.
60.
ZhangHArensEHuizengaCHanTY. Thermal sensation and comfort models for non-uniform and transient environments: part I: local sensation of individual body parts. Build Environ2010; 45: 380–388.
61.
ZhangYCHeHYDaiKQLinZFangZSZhengZM. Thermal responses of face-masked pedestrians during summer: an outdoor investigation under tree-shaded areas. Build Environ2023; 233: 110058.
62.
TangTWZhouXQDaiKQFangZSZhengZM. Comparison of adaptive thermal comfort with face masks in library building in Guangzhou, China. Thermal Sci Eng Prog2023; 37: 101597.
63.
ZhengZMLuJXDaiKQLiuJLLiuWWZhangYCFangZS. Comparison of the adaption of outdoor thermal comfort of pedestrians with face masks in semi-open spaces. Thermal Sci Eng Prog2024; 49: 102429.
64.
TianXYYuJYLiuWW. Facial skin temperature and its relationship with overall thermal sensation during winter in Changsha, China. Indoor Air2022; 24: 13138.
65.
TianXYShiLWangZLiuWW. A thermal comfort evaluation model based on facial skin temperature. Build Environ2023; 235: 110244.
66.
LiDMenassaCCKamatVR. Non-intrusive interpretation of human thermal comfort through analysis of facial infrared thermography. Energy Build2018; 176: 246–261.
