Background
As defined by the World Health Organization in 1983 [
1], sick-building syndrome (SBS) causes symptoms related to the indoor environment reported by occupants of office buildings. These symptoms include fatigue, headache, and irritation of the upper respiratory tract, eyes, nose, throat, and hand or facial skin [
1,
2]. SBS symptoms are associated with personal and environmental factors. Personal factors associated with SBS symptoms include female sex, history of allergies, anxiety, depression, and psychosocial work stress [
3‐
5], while environmental factors include building characteristics (e.g., dampness and poor ventilation) [
6,
7], indoor air pollution (e.g., volatile organic compounds (VOCs) and bioaerosols) [
8,
9], and perceived indoor air quality (IAQ) such as odor and humidity perception [
10,
11]. However, the mechanism by which SBS symptoms are caused is not clear.
Subjective perception of IAQ, including odor perceptions and sensory irritation, is related to indoor air pollutants, such as VOCs and nitrogen oxides [
12]. Sources of odors in indoor environments include human body odor, secondhand smoke, bio-odorants (e.g., mold and animal-derived materials), and cosmetics [
13]. Sensory irritation of the eyes and airways may be due to airborne compounds stimulating the skin or mucosal tissues, which is often described as “dryness.” Sensory irritation and odor perception are often experienced simultaneously.
Most SBS studies have been conducted in office buildings [
9,
14,
15]. However, in our knowledge, studies regarding SBS symptoms of workers in underground spaces in other countries have not been well reported. Worldwide, underground spaces are being used increasingly for various purposes, such as transportation systems and commercial facilities [
16]. In metropolitan centers, underground shopping areas are often crowded with shoppers, passengers, workers, and employees.
Although the IAQ in underground shopping centers in Korea is regulated by the Indoor Air Quality Management Act, workers in specific sections or semi-open stores might be exposed to different levels of indoor air pollution due to different emission sources in each store [
17]. One study reported that the carbon dioxide (CO), formaldehyde (HCHO), and total volatile organic compound (TVOC) concentrations differed significantly (
P < 0.05) in different merchandise sections in nine department stores in China [
18]. Thus, store employees who spend large amounts of time in stores could be exposed significantly of such pollutants.
In the present study, we investigated the subjective health and IAQ of workers in underground shopping stores. The purposes of this study was to examine the relationships between SBS symptoms and the IAQ perceptions of workers, as well as the associations between IAQ perception and store type in underground shopping areas.
Results
The average age of the 314 store workers was 47 ± 13 years and 58% were female. The prevalence of the 16 SBS symptoms in the store workers in the previous month ranged from 12.7 to 57.6% (Table
1). For the SBS symptom groups, the prevalence of SBS symptoms was 43.6% for skin symptoms, 62.4% for eye irritation symptoms, 65.6% for respiratory symptoms, and 64.7% for general symptoms.
Table 1
Prevalence of 16 sick-building-syndrome symptoms in store workers in underground shopping centers in the previous month
Skin | Skin dryness or itching | 137 (43.6) |
Eye irritation | Dry, itching, or irritated eyes | 167 (53.2) |
Tired or strained eyes | 162 (51.6) |
Respiratory | Stuffy or runny nose | 123 (39.2) |
Cough | 116 (36.9) |
Sneezing | 144 (45.9) |
Sore or dry throat | 151 (48.1) |
Wheezing | 49 (15.6) |
Shortness of breath or chest tightness | 52 (16.6) |
General | Nausea or upset stomach | 40 (12.7) |
Headache | 115 (36.6) |
Tiredness, fatigue, or drowsiness | 181 (57.6) |
Nervousness | 115 (36.6) |
Difficulty in remembering things or in concentrating | 90 (28.7) |
Dizziness or lightheadedness | 61 (19.4) |
Feeling depressed | 40 (12.7) |
Table
2 shows the prevalence of SBS symptom groups in the previous month according to demographic and job characteristics. The prevalence of skin, eye irritation, respiratory, and general symptoms differed with several demographic and job characteristics. Particularly, the prevalence of eye irritation and general symptom groups were significantly higher in female workers than in men. Associations SBS symptoms with store type of the workers in the multivariable logistic regression models are presented in Table S3 (Additional file
2).
Table 2
Prevalence of sick-building-syndrome symptoms according to the demographic and job characteristics of store workers in underground shopping centers
Demographic characteristics |
Sex |
Male | 132 | 52 (39.4) | 0.197 | 68 (51.5) | < 0.001 | 80 (60.6) | 0.112 | 75 (56.8) | 0.013 |
Female | 182 | 85 (46.7) | | 128 (70.3) | | 126 (69.2) | | 128 (70.3) | |
Age (years) |
< 40 | 91 | 42 (46.2) | 0.022 | 57 (62.6) | 0.102 | 65 (71.4) | 0.013 | 63 (69.2) | 0.078 |
40–49 | 81 | 45 (55.6) | | 59 (72.8) | | 61 (75.3) | | 59 (72.8) | |
50–59 | 90 | 34 (37.8) | | 52 (57.8) | | 53 (58.9) | | 51 (56.7) | |
≥ 60 | 52 | 16 (30.8) | | 28 (53.8) | | 27 (51.9) | | 30 (57.7) | |
Education |
High school or less | 157 | 66 (42.0) | 0.569 | 95 (60.5) | 0.485 | 98 (62.4) | 0.235 | 100 (63.7) | 0.723 |
College or higher | 157 | 71 (45.2) | | 101 (64.3) | | 108 (68.8) | | 103 (65.6) | |
Smoking status |
No | 250 | 106 (42.4) | 0.385 | 156 (62.4) | 0.988 | 160 (64.0) | 0.237 | 157 (62.8) | 0.175 |
Yes | 64 | 31 (48.4) | | 40 (62.5) | | 46 (71.9) | | 46 (71.9) | |
Job characteristics |
Length of employment (years) |
< 2 | 76 | 31 (40.8) | 0.393 | 51 (67.1) | 0.799 | 51 (67.1) | 0.467 | 53 (69.7) | 0.477 |
2–4 | 86 | 44 (51.2) | | 52 (60.5) | | 61 (70.9) | | 58 (67.4) | |
5–9 | 60 | 26 (43.3) | | 36 (60.0) | | 39 (65.0) | | 35 (58.3) | |
≥ 10 | 92 | 36 (39.1) | | 57 (62.0) | | 55 (59.8) | | 57 (62.0) | |
Hours worked per day (hours) |
< 8 | 42 | 12 (28.6) | 0.035 | 22 (52.4) | 0.149 | 27 (64.3) | 0.847 | 21 (50.0) | 0.033 |
≥ 8 | 272 | 125 (46.0) | | 174 (64.0) | | 179 (65.8) | | 182 (66.9) | |
Type of store |
Food service | 28 | 10 (35.7) | 0.159 | 13 (46.4) | 0.337 | 11 (39.3) | 0.017 | 13 (46.4) | 0.086 |
Clothing | 151 | 64 (42.4) | | 96 (63.6) | | 100 (66.2) | | 96 (63.6) | |
Fashion accessories | 65 | 36 (55.4) | | 42 (64.6) | | 47 (72.3) | | 48 (73.8) | |
Others | 70 | 27 (38.6) | | 45 (64.3) | | 48 (68.6) | | 46 (65.7) | |
Among the store workers, dry air was the most perceived IAQ perception (46.2%), followed by stuffy odor (34.4%), unpleasant odor (28.0%), pungent odor (22.0%), humid air (19.1%), tobacco smoke odor (18.2%), and moldy odor (16.6%). Table
3 shows the cross-correlations between any two IAQ perceptions. All IAQ perceptions were significantly correlated with each other, except for the correlation between humid air and tobacco smoke odor.
Table 3
Spearman correlation coefficients among indicators of indoor air quality perceived by workers in underground shopping centers (n = 314)
Stuffy odor | 1.00 | | | | | | |
Unpleasant odor | 0.67*** | 1.00 | | | | | |
Pungent odor | 0.60*** | 0.71*** | 1.00 | | | | |
Moldy odor | 0.42*** | 0.31*** | 0.38*** | 1.00 | | | |
Tobacco smoke odor | 0.23*** | 0.28*** | 0.29*** | 0.12* | 1.00 | | |
Dry air | 0.19*** | 0.13* | 0.14* | 0.22*** | 0.18** | 1.00 | |
Humid air | 0.14* | 0.22*** | 0.23*** | 0.15** | 0.07 | 0.23*** | 1.00 |
Table
4 shows the results of the multivariable logistic regression analyses of all four SBS symptom groups for the workers according to IAQ perceptions. After adjusting for demographic and job characteristics, most SBS symptoms were significantly associated with all IAQ perceptions. The ORs of the SBS symptoms for IAQ perceptions ranged from 1.81 to 8.07. Furthermore, the relationships between all of the SBS symptom groups and the categorized IAQ perception score were dose-dependent (
P for trend < 0.001). Slightly higher effects of IAQ perceptions on SBS symptoms were observed in the multivariable logistic regression analyses without adjustment for store types (Additional file
2: Table S4).
Table 4
Relationships between sick-building-syndrome symptoms and indoor air quality (IAQ) perceptions of workers in underground shopping centers
Stuffy odor |
No | 1.00 | 1.00 | 1.00 | 1.00 |
Yes | 2.89 (1.73–4.83)*** | 6.39 (3.40–12.01)*** | 4.79 (2.56–8.97)*** | 6.03 (3.12–11.63)*** |
Unpleasant odor |
No | 1.00 | 1.00 | 1.00 | 1.00 |
Yes | 2.08 (1.23–3.51)** | 4.06 (2.15–7.67)*** | 4.00 (2.05–7.81)*** | 4.29 (2.19–8.41)*** |
Pungent odor |
No | 1.00 | 1.00 | 1.00 | 1.00 |
Yes | 3.07 (1.72–5.50)*** | 5.16 (2.44–10.89)*** | 7.33 (3.09–17.4)*** | 4.46 (2.11–9.42)*** |
Moldy odor |
No | 1.00 | 1.00 | 1.00 | 1.00 |
Yes | 2.29 (1.19–4.41)* | 3.65 (1.64–8.13)** | 3.81 (1.59–9.09)** | 2.93 (1.28–6.71)* |
Tobacco smoke odor |
No | 1.00 | 1.00 | 1.00 | 1.00 |
Yes | 1.81 (0.99–3.32) | 2.45 (1.21–4.99)* | 4.04 (1.78–9.13)*** | 3.29 (1.54–7.02)** |
Dry air |
No | 1.00 | 1.00 | 1.00 | 1.00 |
Yes | 5.14 (3.07–8.60)*** | 7.07 (3.99–12.50)*** | 7.84 (4.28–14.35)*** | 6.21 (3.47–11.11)*** |
Humid air |
No | 1.00 | 1.00 | 1.00 | 1.00 |
Yes | 2.16 (1.18–3.93)* | 2.40 (1.22–4.71)* | 3.11 (1.47–6.58)** | 2.37 (1.18–4.76)* |
Categorized IAQ perception scorec |
Category 0 | 1.00 | 1.00 | 1.00 | 1.00 |
Category 1 | 5.62 (2.85–11.06)*** | 4.96 (2.68–9.18)*** | 5.26 (2.83–9.76)*** | 3.80 (2.07–6.98)*** |
Category 2 | 9.92 (4.91–20.05)*** | 19.33 (8.75–42.71)*** | 19.39 (8.47–44.39)*** | 12.89 (5.96–27.9)*** |
p-for trend | < 0.001 | < 0.001 | < 0.001 | < 0.001 |
The relationships between IAQ perception and store type were examined in multivariable logistic analysis adjusting for demographic and job characteristics (Table
5). Participants who worked in clothing (OR = 3.47, 95% CI = 1.10–10.92) and fashion accessory (OR = 4.02, 95% CI = 1.20–13.44) stores were more likely to perceive stuffy odors than those who worked in food services. Participants who worked in clothing (OR = 7.28, 95% CI = 1.64–32.26) and fashion accessory (OR = 5.44, 95% CI = 1.15–25.77) stores were more likely to perceive unpleasant odors than those who worked in food services. Participants who worked in fashion-accessory stores (OR = 13.11, 95% CI = 1.63–105.35) were more likely to perceive a moldy odor than those who worked in food services. Participants who worked in clothing (OR = 2.74, 95% CI = 1.11–6.78) and fashion accessory (OR = 3.46, 95% CI = 1.28–9.35) stores were more likely to perceive dry air than those who worked in food services. Participants who worked in clothing (OR = 2.92, 95% CI = 1.33–6.38) and fashion accessory (OR = 3.25, 95% CI =1.37–7.71) stores were more likely to have high IAQ perception score categories than those who worked in food services. However, pungent odor, tobacco smoke odor, and humid air were not associated with store type.
Table 5
Relationships between perceived indoor air quality (IAQ) and type of store for workers in underground shopping centers
Stuffy odora | Food service | 1.00 |
Clothing | 3.47 (1.10–10.92)* |
Fashion accessories | 4.02 (1.20–13.44)* |
Others | 2.54 (0.75–8.59) |
Unpleasant odorb | Food service | 1.00 |
Clothing | 7.28 (1.64–32.26)** |
Fashion accessories | 5.44 (1.15–25.77)* |
Others | 4.64 (0.98–21.94) |
Pungent odora | Food service | 1.00 |
Clothing | 1.75 (0.55–5.55) |
Fashion accessories | 1.76 (0.51–6.05) |
Others | 1.30 (0.37–4.54) |
Moldy odorb | Food service | 1.00 |
Clothing | 5.32 (0.68–41.65) |
Fashion accessories | 13.11 (1.63–105.35)** |
Others | 4.29 (0.51–36.03) |
Tobacco smoke odorb | Food service | 1.00 |
Clothing | 1.60 (0.51–4.96) |
Fashion accessories | 1.25 (0.35–4.45) |
Others | 1.38 (0.40–4.79) |
Dry airb | Food service | 1.00 |
Clothing | 2.74 (1.11–6.78)* |
Fashion accessories | 3.46 (1.28–9.35)* |
Others | 1.97 (0.74–5.24) |
Humid airb | Food service | 1.00 |
Clothing | 0.40 (0.16–1.03) |
Fashion accessories | 0.71 (0.26–2.00) |
Others | 0.80 (0.29–2.17) |
Categorized IAQ perception scoreb,c | Food service | 1.00 |
Clothing | 2.92 (1.33–6.38)** |
Fashion accessories | 3.25 (1.37–7.71)** |
Others | 2.05 (0.88–4.78) |
Discussion
Investigation of 16 SBS symptoms for store workers in underground shopping centers revealed that about one to six out of ten workers experienced at least one SBS symptom at their stores in the previous months. The four SBS symptom groups of store workers in underground shopping centers were associated with almost all IAQ perceptions. When IAQ perceptions were dependent variables, several IAQ perceptions were significantly associated with store types of the workers. Particularly, workers in clothing or fashion-accessory stores were more likely to experience several IAQ perceptions than other types of stores. Overall, their effects on IAQ perceptions were higher for workers in fashion-accessory stores than those in clothing stores.
For each SBS symptom group, about half of the workers in stores in underground shopping centers experienced at least one SBS symptom in the previous month. Of the SBS symptom groups, the prevalence of respiratory symptoms was highest. Overall, the percentage of women in all SBS symptom groups was higher than for men, similar to previous studies [
3,
11]. This might be because women are more sensitive to SBS symptoms than men [
8]. Age, hours worked per day, and store type were associated with several SBS symptom groups.
Workers most often perceived dry air, followed by stuffy odor, unpleasant odor, pungent odor, humid air, tobacco smoke odor, and moldy odor. Most IAQ perceptions were significantly correlated with each other. The correlation was highest between unpleasant and pungent odors. The correlation coefficients between stuffy odor and unpleasant or pungent odors were greater than 0.5, while the other correlation coefficients were less than 0.5. This indicated that different correlation coefficients (low or high) with each other reflected different aspects of the perceived IAQ. Similar findings have been reported when the parents of children reported IAQ perceptions for the home environment in China [
22].
Almost all IAQ perceptions were significantly associated with SBS symptom groups in the multivariable logistic analyses. Overall, the IAQ perceptions had higher ORs for respiratory symptoms than for skin, eye irritation, or general symptoms of workers. These trends were consistent with the relationships between SBS symptoms and categorized IAQ perception scores. Dose-dependent relationships were observed between the SBS symptoms and categorized IAQ perception scores. Our findings indicated that IAQ perception might be associated with SBS symptoms of store workers in underground shopping centers. Similar associations have been reported in previous studies. The sensation of dryness among office workers in northern Sweden was associated with SBS symptoms [
23]. Perceived stuffy air, dry air, and unpleasant odor were significantly associated with several SBS symptom of workers in public and private companies in Italy [
5]. A study conducted in Chongqing, China, reported that IAQ perceptions of parents of children at home were associated with SBS symptoms [
10].
Store type was associated with several IAQ perceptions, especially stuffy odor, unpleasant odor, moldy odor, dry air, and categorized IAQ perception scores. Particularly, people who worked in clothing or fashion-accessory stores were more likely to experience several IAQ perceptions and categorized IAQ perception scores than those who worked in food services. Overall, the effects on IAQ perception or categorized IAQ perception score were higher for workers in fashion-accessory stores than those in clothing stores. This suggests that the IAQ may be lower in fashion-accessory stores than in other store types.
The IAQ of stores in underground shopping centers might differ according to the merchandise sold in that store. Fabrics and leather merchandise can contain formaldehyde-based adhesives [
24]. The fashion-accessory stores in the present study sold mainly leather products, including shoes, bags, wallets, and backpacks. A study in China reported that when the HCHO and TVOC concentrations were measured in food, clothing, electronic products, leather products, and cosmetics zones in nine underground malls, the HCHO concentrations were generally higher (up to 300 μg/m
3) in the leather zone than in the other zone types [
25]. In that study, the TVOC concentrations were highest in food zones, followed by cosmetic and leather zones. In our study, those who worked in food stores had the lowest ORs on IAQ perception. The food stores we studied included restaurants, cafes, and bakeshops. Although restaurants might have emission sources due to cooking activity, cafes and bakeshops might not have significant emission sources. Therefore, the IAQ perception of the food store workers would not be significantly affected.
This is first study to examined SBS symptoms in store workers in underground shopping areas and their relationships with IAQ perception. We also examined the relationships between the workers’ IAQ perceptions and store type.
This study had several limitations. Because it was cross-sectional, we could not infer that IAQ perceptions were causally associated with the workers’ SBS symptoms. Moreover, because we selected participants in nine underground shopping centers, it might not have been representative of all workers in underground shopping centers in Seoul. Selection of the nine underground shopping centers and 33 to 36 store workers considering sex and age ratios in each center might have biases. Previous studies reported that sex and age was associated with SBS symptoms of workers or occupants in indoor places [
3,
8]. Thus, controlling the sex and age ratios across the underground shopping centers might reduce variation of SBS symptoms in different underground shopping centers.
Another limitation was that the participants might have variation of reporting SBS symptoms and IAQ perceptions depending on their sensitivity because we did not use objective methods such as medical examinations by physicians or measurement of IAQ with monitors in each store. Prevalence of SBS symptoms of store workers in underground shopping centers might be excessively estimated because we considered they had SBS symptoms if they answered “sometimes” or “frequently.” Workers with negative disposition might report more SBS symptoms or signs of discomfort for the work environment. Furthermore, recall bias might have affected the prevalence of personal SBS symptoms or IAQ perception. However, the recall bias for SBS symptoms and IAQ perception might not have been a critical issue in our study, since the recall period was short (the previous month).
Although we included several demographic and job factors, there might have been residual confounding of SBS symptoms or IAQ perceptions. Another study reported that personal factors such as a history of allergic disease, anxiety, depression, and psychosocial work stress were risk factors for SBS symptoms [
3‐
5]. Environmental factors, including dampness and ventilation, might also be associated with SBS symptoms or IAQ perception [
6,
7]. Unfortunately, we did not measure these factors.
The IAQ in underground shopping centers in Korea is regulated by the Indoor Air Quality Management Act. According to the Act, the IAQ should be measured at a passage. The Act was mainly focused on the shoppers or passengers rather than on store workers. In the Korean Occupational Safety and Health Act, there was limited policy for management of IAQ in such small store in the underground shopping centers. We found that a large percentage of the store workers had SBS symptoms, which were associated with type of stores or IAQ perception. The IAQ perception of the store workers was associated with the types of stores. Further research should investigate IAQ using an objective method at the working-area-level in underground shopping centers.