Office environments and worker satisfaction with thermal and air environments during and after the COVID-19 pandemic in Japan

• Surveys in 22 offices were conducted during and after the pandemic in Japan. • Workdays at the office increased and those at home decreased after the pandemic. • Worker satisfaction with the air environment increased after the pandemic. • A sign of good ventilation conditions may enhance worker satisfaction. • Installing air filters and air cleaners may enhance worker satisfaction. The coronavirus disease 2019 (COVID-19) pandemic has changed office environments, worker satisfaction, and the associations between them. As indoor environments with high worker satisfaction are achieved by properly maintaining indoor environmental quality factors, understanding the associations between office environments and worker satisfaction is imperative. In this study, questionnaire surveys and environmental measurements were conducted on 916 workers during the pandemic (November–December 2020) and 738 workers after the pandemic (July–August 2023) in 22 offices in Japan. The proportion of offices implementing "increasing the amount of outdoor air" and "natural ventilation by opening the windows" decreased from 59% to 18% and from 50% to 25%, respectively, suggesting a reduction in these practices after the pandemic. Most buildings met the relevant guideline values for temperature (18–28 °C), relative humidity (40–70%), CO 2 concentration (≤1000 ppm), and PM 2.5 mass concentration (≤15 μg/m 3 ) during and after the pandemic. Multilevel linear regression analyses showed that lower PM 2.5 mass concentrations were correlated with higher worker satisfaction with the thermal environment during the pandemic and with the air environment both during and after the pandemic even though PM 2.5 is invisible and odorless. These results suggests that confounding factors such as "increasing the amount of outdoor air," "natural ventilation by opening the windows," "installing the medium-efficiency particulate air (MEPA) filters," and "installing the air cleaners" affect worker satisfaction. Therefore, these countermeasures changed the associations between office environments and worker satisfaction. These findings will help enhance worker satisfaction in the post-COVID-19 era.