Work productivity in the office and at home during the COVID‐19 pandemic: A cross‐sectional analysis of office workers in Japan

Abstract The coronavirus disease 2019 (COVID‐19) pandemic has drastically changed work styles and environments. Given the coexistence of work in the office and work from home (WFH) in the future, studies are needed to identify ways to increase productivity when working in both places. We conducted a questionnaire survey and environment measurements of 916 workers in 22 offices across 2 weeks in November–December 2020 in Japan. While average workdays at the offices decreased from 4.9 to 3.9 days/week, those at homes increased from 0.1 to 1.1 days/week due to COVID‐19, indicating an increase in the relative importance of WFH. Compared to the office, the satisfaction rate was lower for lighting, spatial, and information technology (IT) environments, but higher for thermal, air, and sound environments at home. Although it was easier to concentrate on work and to refresh at home, workers experienced challenges associated with business communication from home. Meanwhile, in the office, satisfaction with COVID‐19 countermeasures was significantly associated with work productivity. Furthermore, lower PM2.5 concentration was associated with greater satisfaction with COVID‐19 countermeasures, indicating that reducing PM2.5 may increase satisfaction with COVID‐19 countermeasures and work productivity. We expect these findings will help improve work productivity in the New Normal era.

state of emergency in 2020, however, WFH became a more common practice for workers worldwide. Currently, although workers are gradually moving back into office buildings, large numbers continue to WFH.
COVID-19 has also changed the work environment. Many workplaces have introduced countermeasures based on the modes of transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2): physical distancing as a countermeasure for droplet transmission, and cleaning and disinfecting surfaces as a countermeasure for contact transmission. In addition, evidence on airborne transmission is increasing, [2][3][4][5][6][7] with the World Health Organization (WHO) 8 and the Centers for Disease Control and Prevention (CDC) 9 recognizing airborne transmission as a mode of transmission for SARS-CoV-2. This has led to the issuance [10][11][12] and review 13   Given the drastic changes to work styles and work environments during compared to before the COVID-19 pandemic, it would be interesting to examine productivity in current work styles and work environments. While many studies have examined the relationship between the work environment in the office and productivity before the COVID-19 pandemic, [14][15][16][17][18][19] few studies have been conducted since the pandemic began. Several papers have recently focused on the effects of WFH. 20,21 However, given the likely coexistence of work in the office and WFH in the New Normal era, it is necessary to examine the relationship between work environment and productivity both in the office and at home, in particular, which work environments (eg, lighting, thermal, air, sound, spatial, and information technology (IT) environment) are strongly associated with productivity.
We conducted a survey on work style, work environment and productivity in the offices and at home during the COVID-19 pandemic. The purpose of this study was to investigate the link between different work styles and work environments and productivity during the COVID-19 pandemic, and to explore ways to improve productivity in the New Normal era.

| Study design
This survey was conducted across 2 weeks in November and December 2020 (during the COVID-19 pandemic). Figure 1 shows the trend in the number of newly confirmed cases of COVID-19. 22 The survey was carried out in the beginning of a third wave (average 2120 (range: 770-3206) cases/day). We recruited building operators and office workers from 22 buildings of 18 companies in Japan.
The detailed sample size in each building is shown in

| Questionnaire survey
Two types of questionnaires were administered, one to building operators and the other to office workers. The questionnaire items are shown in Table S2. Briefly, the questionnaire for building operators covered building information, HVAC systems, and their maintenance. Questionnaire items about system maintenance were taken from several guidelines on COVID-19 issued by American, 10,23,24 European, 11 and Japanese organizations. 12 The questionnaire for workers covered individual attributes, work style before/during COVID-19, office/ home work environment, productivity (concentration on work and creative tasks, ability to relax and refresh with ease, and ease of communication), lifestyle and mental health. We used the same questions and answers to the work style before and during COVID-19 to compare 2 periods equally. Similarly, we did to the office and home work environment. Participants responded to items about the office/home work environment and productivity on a 7-point scale and 5-point scale, respectively. Lifestyle was investigated using the International Physical Activity Questionnaire (IPAQ) short form 25,26 and the Athens Insomnia Scale (AIS). 27 Mental health was examined using the K6 28 and Work Functioning Impairment Scale (WFun). 29

| Office environment measurements
Indoor temperature and humidity, CO 2 concentration, and PM 2.5 mass concentration were used as office environment factors. Indoor temperature, relative humidity, and CO 2 concentration were measured at 5-min intervals for 2 weeks using a logger (TR-76Ui; T&D Corp.) placed on the desk of a representative worker. At the same

Practical implications
• At home, the spatial, sound, and information technology (IT) environment were important for work productivity.
• In the office, in addition to the spatial, sound, and IT environment, satisfaction with COVID-19 countermeasures was important for work productivity.
• Lower PM 2.5 concentration was associated with greater satisfaction with COVID-19 countermeasures.
• At present, CO 2 concentration is considered as an important index of poorly ventilated closed spaces which is one of the risk factors for COVID-19.
• PM 2.5 may be an important index of workers' satisfaction with COVID-19 countermeasures and productivity. time, PM 2.5 mass concentration was measured at 1-min intervals using a logger placed next to TR-76Ui (PMT-2500; Komyo Rikagaku Kogyo K.K.). These loggers were kept away from heat-generating or aerosol-generating devices such as printers because printers are a source of PM 2.5 in the office. They were also placed away from direct sunlight because it may affect measurements of temperature and data measured using laser light scattering methods. Office environment factors from 9 a.m. to 5 p.m. on weekdays were averaged and used in the analyses to take the regular work hours into consideration. Outdoor temperature and humidity values were obtained from the closest local meteorological observatory, and outdoor PM 2.5 from the closest local Atmospheric Environmental Regional Observation System (AEROS) to each building.

| Statistical analysis
Proportions of related samples were compared using the marginal homogeneity test, an extension of McNemar's test. Multiple linear regression analysis was used to examine the association between satisfaction with the office/home environment and productivity.
Model A to E included productivity as a dependent variable and satisfaction with the environment as an independent variable. Models were adjusted for age; gender; work type (engineer or not); sleep condition (AIS score); and physical activity (IPAQ Short).
The association between office environment factors and satisfaction with COVID-19 countermeasures was analyzed using a multilevel linear regression model. The dependent variable was satisfaction (on a 7-point scale) with COVID-19 countermeasures. A two-level random intercept model was used in which office workerlevel variables (age, gender, work type (engineer or not), work style (work days at the office) and lifestyle (AIS score)) were nested within office-level variables (temperature, relative humidity, CO 2 concentration and PM 2.5 mass concentration). Office worker-level variables were centered around the mean for each office, while office-level variables were centered around the overall mean. Regression coefficients were estimated using the maximum likelihood method. All p values were two-sided, and a two-sided p value less than 0.05 was considered statistically significant. All analyses were performed using SPSS Ver. 26 (SPSS Inc.,). Table 1 shows the characteristics of 916 workers. About 80% of workers answered the questionnaire in the office. Age of workers ranged from <30 years to ≥60 years, and three-quarters of the workers were men. Two-thirds of the workers were technical staff in research and development or design and engineering. Regarding health literacy, 95.1% of workers wore masks during work, 77.0% of workers always washed their hands after arriving at the office, and about 47.5% always measured their body temperature before leaving for the office.

| Baseline characteristics of workers, work styles and work environment
Data from 777 workers who had worked in their current workplace for ≥1 year were used to compare work styles before and during COVID-19. Average workdays at the office decreased from 4.9 to 3.9 days/week, while those at home increased from 0.1 to 1.1 days/week. Average number of days engaging in online meetings increased from 0.4 to 2.1 days/week ( Figure 2).

F I G U R E 1 Trend in the number of newly confirmed cases of COVID-19
Data from 432 workers who worked ≥1 day/week both in the office and at home were used to compare environmental satisfaction and productivity. Compared to the office, significantly fewer workers were satisfied with the lighting (illumination of the desk), spatial (room size), and IT environment (Internet connection speed and stability) at home ( Figure 3). In contrast, more workers were satisfied with the thermal (temperature, humidity, etc.), air (stagnation), and sound environment (noise) at home. In terms of productivity, although it was easier to concentrate on work and creative tasks, and to relax and refresh at home than in the office, workers at home experienced challenges associated with business communication ( Figure 4). Figure 5 shows the indoor temperature, relative humidity, CO 2 concentration, and PM 2.5 mass concentration in 21 buildings; measurements were not conducted in 1 building. Average indoor temperature was 24.9℃, and all buildings met the air environment requirement (17-28℃) of the Act on Maintenance of Sanitation in Buildings.

| Office environment measurements
Average relative humidity was 36.1%, and 13 out of 21 buildings had levels below 40% (air environment requirement is 40-70%).
Average CO 2 concentration was 666 ppm, and only 1 building had an average reading above 1000 ppm (air environment requirement is ≤1000 ppm). Average PM 2.5 mass concentration was 4.3 µg/m 3 .

| Association between satisfaction with office/ home environment and productivity
The results of multiple linear regression analyses are shown in Table 2A-E. The most important environmental factors for productivity were different between the office and home. In terms of concentration on work, the sound environment was the most important in the office, while spatial environment was the most important at home. For creative tasks, spatial environment was the most important both in the office and at home. In terms of the ability to relax and refresh with ease, spatial environment was the most important in the office, while the air environment was the most important at home. Spatial and lighting environments in the office, and spatial and IT environments at home were closely correlated with ease of communication. Furthermore, satisfaction with COVID-19 countermeasures in the office was significantly associated with concentration on work, creative tasks, and the ability to relax and refresh with ease.

| Satisfaction with COVID-19 countermeasures and quality of the indoor environment
Our findings suggested that COVID-19 countermeasures may affect productivity in the office. We therefore analyzed the association between office environment measurements and satisfaction with COVID-19 countermeasures, excluding data from the building with abnormally high CO 2 concentrations (Building U in Figure 5).
Temperature and relative humidity were not associated with satisfaction with COVID-19 countermeasures. In contrast, lower CO 2 and PM 2.5 levels were correlated with higher satisfaction with COVID-19 countermeasures ( Figure 6). A similar trend was observed in the For reference, we show the concrete COVID-19 countermeasures conducted in 20 buildings except for 2 buildings whose information could not be collected or disclosed (Table S4).

| Work style and work environment during the COVID-19 pandemic
In 2019, only 4.8% of workers had engaged in WFH practices, com-

| How to improve satisfaction with COVID-19 countermeasures
The present results showed that satisfaction with COVID-19 countermeasures was significantly associated with productivity in the office. This suggests that increasing satisfaction with COVID-19 countermeasures may increase productivity in the office.

TA B L E 2 (Continued)
Furthermore, the present study also indicated that a lower PM 2.  (Table S3) satisfaction with COVID-19 countermeasures/productivity might weaken when the world turns to be normal. However, given that the pandemic occurred again and again in history, we believe our findings is useful when it comes to the future pandemic.

| How to increase work productivity in the new normal era
The present study shows that both the type of work and work environment must be considered to ensure sufficient productivity in a workplace. As shown in Figure 4, it was easier to concentrate on work at home than in the office. However, as shown in Table 2, the quality of spatial, sound, and IT environments such as adequate room size, quietness, and Internet speed were necessary for concentration.
While it was easier to communicate with others in the office than at home, smoother communication required higher quality spatial and lighting environments. Therefore, both the type of work and the quality of the work environment need to be considered when selecting an appropriate workplace to facilitate productive work. Interestingly, a third type of work environment outside the home and office, such as a satellite office and co-working space, has attracted more attention recently, 32 and may be another solution for those whose homes and offices do not reach a certain level as work environments.

| Study limitations
This study has several limitations. First, because the majority of workers in this study were engineers, the present results may have some bias. For example, the type of work and work style of engineers differ from those of non-engineers; thus, the present results may not be applicable to non-engineers. We also compared the distributions of age and gender in the present survey with those in the Labor Force Survey in Japan. 33 The proportion of workers ≥60 years  We expect these findings will help improve work productivity in the New Normal era.

ACK N OWLED G EM ENTS
This study was conducted as a part of research of the "Investigative committee for the guideline on air-conditioning and ventilation after

CO N FLI C T O F I NTE R E S T
No conflict of interest has been declared by the authors.

PE E R R E V I E W
The peer review history for this article is available at https://publo ns.com/publo n/10.1111/ina.12913.