Research indicates a higher prevalence of SS in the young group than their elder counterparts. Notably, a French epidemiological survey comprising 5,000 individuals revealed that individuals under the age of 35 exhibit a higher prevalence of SS, surpassing 60% of the population within this age range (26). Similarly, a survey conducted in South Korea found that the younger group ranging from 15 to 44 years old displays a greater likelihood of developing SS compared to individuals over the age of 45 (27). Correspondingly, another study involving 22,085 women in China unveiled that the younger group, specifically those aged 20 to 30, is more susceptible to sensitive or highly SS in comparison to the elder group, aged 30 and above (28). These findings suggest a plausible mechanism wherein the nerve innervation function in the human body, related to touch and pain, diminishes as individual age (29).

Extensive empirical studies have consistently shown that women are more prone to SS than men. Notably, a study based on 3,012 participants in India found that the proportion of women experiencing “sensitive” or “very sensitive” skin is significantly higher (36.7%) compared to the men (27.9%) (30). These findings are consistent with multiple investigations conducted domestically and internationally, which consistently demonstrated that women are more likely to develop SS than men (23, 31, 32). One plausible explanation for this disparity could be the significant differences in epidermis and dermis thickness between males and females (33), with males exhibiting a greater thickness. Consequently, the skin of males is less permeable than that of females, making it less susceptible to the effects of irritants or allergens. Additionally, the periodic hormonal fluctuations experienced by women contribute to increased SS (34).

While no significant racial differences were observed in the prevalence of SS, variances in sensory perception among different races have been documented. For instance, European Americans tend to exhibit heightened sensitivity to wind, Asians are more sensitive to spicy food, and Hispanics display relatively lower responsiveness to alcohol (35). There are also reports suggesting that African Americans have a higher incidence of SS compared to European Americans (36). As human skin exhibits individual differences, further parallel studies are required to ascertain the true racial disparities in SS (37).

Medical personnel wear masks for extended durations while on duty, and studies have documented skin-related symptoms, such as redness and itching, associated with mask-wearing among medical staff (38). However, a survey revealed a prevalence of SS found that there was no significant difference between the socio-professional categories in SS (39). Hence, further research is required to shed light on the influence of occupation on SS.

Emotional change has been identified as a contributing factor to the development of SS (32, 34). Individuals with SS are more likely to experience discomfort, such as tingling and itching, during the periods of emotional fluctuation compared to individuals without SS (27). Moreover, there is a significant correlation between the occurrence of SS and anxiety, suggesting that anxiety may play a role in the manifestation of SS symptoms (13). Additionally, depression has been associated with SS, where facial flushing is recognized as the primary clinical manifestation (31).

Compared to neutral skin, dry, oily, and mixed skin exhibit varying degrees of damage to the skin barrier function, rendering them more susceptible to SS and inflammatory skin diseases (40, 41). Epidemiological studies have further confirmed that these skin types are risk factors for SS diseases (28, 42).

Individuals with poor sleep quality exhibit an increase in transepidermal water loss (TEWL) compared to those with good sleep quality, consequently leading to the damage of skin barrier (43). Sleep disorders contribute to an elevation in oxidative stress, resulting in alterations in skin homeostasis and the disruption of inflammatory pathways, ultimately leading to the dysfunction of the skin barrier (44, 45). Impaired skin barrier function and reduced water content in the stratum corneum are significant pathophysiological characteristics observed in individuals with SS (46). An epidemiological survey conducted across multiple countries, including Brazil, China, France, Russia and the United States, found a higher prevalence of SS among subjects with sleep disorders (47).

The presence of estrogen receptors in the epidermis impacts skin hydration and the functionality of skin barrier, as estrogen levels directly influence these factors (48). Muizzuddin’s research demonstrated that the strength and dryness of skin barrier, as well as the sensitivity to lactic acid stinging, vary in response to fluctuations in estrogen levels during the menstrual cycle (49). A questionnaire survey involving Dutch women revealed that approximately 42% of premenopausal women experienced an increased sense of SS prior to and during the menstrual cycle (34).

Capsaicin, a biologically active component found abundantly in peppers, interacts with the Capsaicin receptor, a transmembrane channel protein widely expressed in skin tissue (50). The activation of the Capsaicin receptor, known as TRPV1, stimulates the release of neuropeptides and excitatory amino acids from free nerve endings, ultimately leading to the sensation of pain in the cerebral cortex (51). Studies have revealed that individuals of Asian descent exhibit increased susceptibility to SS when exposed to the stimulation of a spicy diet (35). A survey conducted among college students in China further confirmed that a spicy diet serves as a risk factor for SS (32). Moreover, experimental evidence has demonstrated that inhibiting the expression of TRPV1 can be effective in treating SS (52).

Research indicates a positive correlation between the frequency of cosmetic usage and the prevalence of SS (53). Specifically, when women utilize multiple types of cosmetics and makeup removers on a daily basis, it can easily trigger SS (28). Brenaut carried out a meta-analysis of 13 surveys, which collectively identified cosmetics as a common trigger for SS, and excessive or improper usage exacerbating this reaction (54). One potential explanation for this phenomenon is that frequent and simultaneous use of cosmetics may thin the stratum corneum on free ending is compromised, leading to a significant increase in nerve sensation input and signal release, resulting in uncomfortable sensations (55). Additionally, a thinner stratum corneum can enhance the penetration of capsaicin, thereby increasing SS (56).

Pavithra carried out a proteomic analysis on primary human keratinocytes exposed to long-term cigarette smoke condensate, revealing that the differentially expressed proteins were predominantly associated with the integrity of the epithelial barrier and the anti-inflammatory response (57). Moreover, excessive smoking over 20 cigarettes per day for at least 2 years can disrupt the homeostasis of the epidermal permeability barrier (58). Studies simulating cigarette smoke exposure have further shown that prolonged and/or repeated exposure to high levels of toxic smoke pollutants can impair the function of the epidermal barrier (59). Multiple epidemiological investigations have also confirmed a positive correlation between smoking and the prevalence of SS (60, 61).

Epidemiological studies have established a link between alcohol consumption and an increase in the prevalence of SS (35). It is believed that the decomposition of ethanol into acetaldehyde induces vasodilation, leading to facial burning and flushing (62, 63).

Prior research has demonstrated that various stimuli, including pain sensation, may undergo changes during and after exercise, potentially attributed to the activation of exercise-induced opioid substances (64). Limbs exhibit a decrease in skin thermal sensitivity only after high-intensity exercise (65). The tingling, burning and itching symptoms associated with SS are also connected to sensory nerve dysfunction in the skin (66). In addition, research has found that spending more time exercising is associated with a lower risk of developing depression (67), which potentially reducing susceptibility to SS (31).

A large body of literature has examined the effects of ultraviolet (UV) rays from sunlight on the skin. UV rays are categorized into UVA, UVB, and UVC based on their wavelengths, with UVC being absorbed by the ozone layer (69). UVA primarily impacts the dermis and promotes oxidative damage to DNA, while UVB mainly affects the epidermis (70). Studies have indicated that exposure of human keratinocyte to UVB radiation can disrupt the hydration of stratum corneum (71). Numerous experiments utilizing UVB irradiation on epidermal mice have revealed epidermal barrier dysfunction, including increased epidermal thickness, elevated TEWL, and reduced water content in the stratum corneum (72, 73). Furthermore, UVB radiation induces oxidative damage and triggers inflammatory reactions to keratinocyte on the skin surface (74–76), herein contributing to the development of SS. A survey performed on the Chinese population highlighted the gender and radiation dose-related changes in stratum corneum function caused by ultraviolet radiation (77). Building upon this, Francesca and his collaborators discovered a significant cumulative effect of UV and O₃ in reducing skin barrier-related proteins, such as silk fibroin and skin protein (78). Epidemiological investigations have confirmed that sunlight represents a significant factor influencing the prevalence of SS (32, 79, 80).

Temperatures exceeding 43°C have been shown to directly activate TRPV1 (81). TRPV1 is a specific member of the transient receptor potential (TRP) superfamily of ion channels. Which are found in various tissues throughout the body. TRPV1 leading to the sensation of heat and pain (50). Research has found that the expression of TRPV1 in SS is enhanced, leading to overload of harmful stimuli (82). Therefore, patients are prone to experiencing abnormal heat and pain sensations. In the case of SS, inflammatory mediators can significantly lower the activation threshold of TRPV1 (83). Epidemiological studies have identified changes in temperature and humidity as triggering factors for SS (54, 80). Individuals with SS are particularly sensitive to TEWL and ambient temperature (84). Research has demonstrated that low humidity is more likely to induce SS (23, 54).

The prevalence of SS has been associated with air pollution (22, 85). Among air pollutants, fine particulate matter (PM_2.5) has been extensively studied. PM_2.5 exposure in human keratinocytes has been shown to increase Cyclooxygenase2 (COX-2)/Prostaglandin E2 (PGE2) levels, leading to the downregulation of expression of silk fibroin (86, 87). Treatment of human and mouse skin equivalents with PM_2.5 has also been found to inhibit the expression of fibronectin and increase TEWL, thus compromising the integrity of the skin barrier (88). Additionally, PM_2.5 can disrupt the morphology and structure of keratinocyte, further compromising the skin barrier (89). Previously, it has been found that exposure to nitrogen dioxide (NO₂) increases the TEWL value of skin, leading to damage to the skin barrier (90). Low concentration of carbon monoxide (CO) can inhibit the release of tumor necrosis factor-α，interleukin-1β and interleukin-10 reducing inflammatory response, therefore CO may reduce damage to the skin barrier (91), It has been shown that ozone (O₃) exposure will lead to various skin inflammation through redox pathway (92), At the same time, O₃ therapy can be applied to the clinical treatment of various inflammatory skin (93, 94), but its role in SS needs further research. Air pollution can cause anxiety in people (17), and the prevalence of SS is significantly correlated with anxiety (13).

The growing body of evidence supports the notion that the BEs plays a significant role in development of NCDs through changes in environmental exposure and health-related lifestyles. For instance, individuals residing in densely populated communities often face a higher risk of obesity (96). As reported, a densely populated community are likely to emit more air pollutants (97) that contribute to an increase in risk of obesity (98, 99). Moreover, population density has a positive correlation with PM₁₀ concentration (100), and elevated PM₁₀ levels have been shown to compromise lung function (101, 102), consequently impacting cardiovascular health (103). Interestingly, research have indicated that an increase in coverage ratio of greenspaces benefits to lower the prevalence of obesity (104), hypertension and cardiovascular disease (105, 106), as well as reduce the mortality of cardiovascular disease (107, 108). This relationship can be attributable for that urban greenness promotes physical activity (109) and mitigates exposure to PM_2.5 (110). A survey conducted in Apulia found the impact of green space use on depressive symptoms, and the mediating role of perceived social support in the association (111). Nighttime artificial light (ALAN) has emerged as a risk factor for physiological functions, with a significant correlation observed between higher levels of nighttime outdoor light and poor sleep patterns (112). Notably, ALAN is likely to reduce sleep duration (113), which is more prevalent in communities with higher poverty levels (114). Moreover, sleep disturbance may play a role in anxiety and depressive disorders (111). Besides, research studies have demonstrated that the exposure to Artificial Light at Night (ALAN) during adolescence could potentially elevate the risk of developing atopic diseases during youth (115). Further research is warranted to substantiate causal relationships, particularly those related to circadian rhythm disorders and endocrine pathways. Additionally, a high density of road intersections increases the likelihood of walking and cycling (116). Utilizing public transportation necessitates walking or cycling to bus transits, resulting in elevated levels of moderate physical activity (117, 118). As observed, physical inactivity in both adults and children elevates the risk of overweight/obesity (119–121). Conversely, engaging in physical activity helps to decrease the prevalence and mortality of cardiovascular disease (122, 123). Furthermore, a higher density of fast food restaurants has been associated with a greater prevalence of obesity (124) due to the residential surrounding food BEs have potentials to alter residents’ dietary behavior and quality (125, 126), thereby affecting their health.

Overall, the BEs exerts an influence on individual health through changes in exposure to environmental hazardous stressors and health-related lifestyles (25). SS, identified as a common clinical symptom, results from various internal and external factors. Given the close relationships between BEs and individuals’ daily routines, it is plausible that BEs may also have potential impacts on SS.

The relationship between the BEs and the development of SS has not yet been fully explored. Based on identified pathways from BEs to other NCDs, our study aims to establish a theoretical framework connecting BEs and SS, providing a scientific foundation for future epidemiological investigations, basic research, and clinical studies. As previously mentioned, SS development may be influenced by factors such as population density, the availability of green space, street design, and the food environment, Additionally, natural environmental exposure and individual behaviors serve as mediating pathways that can contribute to human skin inflammation and the emergence of adverse emotions, ultimately culminating in the manifestation of SS. When skin inflammation occurs, a substantial quantity of inflammatory cytokines and chemokines is released, leading to heightened sensitivity of nerve fibers within the epidermis and an increased responsiveness to external stimuli (127, 128). The association between negative emotions, such as anxiety and depression, and SS has primarily been explored through epidemiological surveys, which have demonstrated a positive correlation. However, there remains a dearth of experimental research evidence on this subject (Figure 2).