A systematic review of ventilation conditions and airborne particulate matter levels in urban offices

Many working activities are carried out in office buildings that are located in urban areas. Several studies have shown that these workplaces are likely to present poor indoor environmental quality (IEQ) due to inadequate ventilation rates, compromised thermal comfort conditions, and/or high concentration of air pollutants, such as particulate matter. This study aimed to review ventilation conditions, based on carbon dioxide (CO₂ ) concentrations, and indoor airborne particulate matter (PM_2.5 and PM₁₀ ) levels assessed in offices worldwide. The approach carried out in this work followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Six databases (Scopus, Web of Science, PubMed, Inspec, Science Direct, and Dimensions) were used to search for peer-reviewed articles on the subject of IEQ, in particular, those reporting data for the levels of CO₂ and particulate matter in offices, published during the last decade. Firstly, 394 records were identified, resulting in 23 articles included in the review after the screening process and the implementation of eligibility criteria. Based on the results and considering the mean concentration reported, office environments present, in general, acceptable ventilation conditions (mean: 665 ppm). However, the few cases of studies that reported CO₂ values exceeding 1000 ppm identified situations of high occupancy density and inadequate operation of heating, ventilation, and air conditioning (HVAC) systems as the unequivocal causative factors. In turn, PM_2.5 and PM₁₀ seemed to be IEQ parameters that are even more critical to be tackled in offices, with the reported overall mean values (36 and 63 μg/m³ ) exceeding the current World Health Organization (WHO) guidelines (15 and 45 μg/m³ ). The highest aerosol concentrations were typically found in naturally ventilated buildings and were mostly associated with the influence of high levels of particles introduced indoors through the outdoor air. Overall, measures for improving IEQ in offices toward promoting healthy and safe environments for workers include strategies to periodically control IEQ, ensure the adequate percentage of fresh air and maintenance of the mechanical ventilation systems (operation, maintenance, and air filtration efficiency), and adjust occupancy to the room dimensions and ventilation conditions.

Indoor humidity levels and associations with reported symptoms in office buildings

Moderate indoor relative humidity (RH) levels (i.e., 40%-60%) may minimize transmission and viability of some viruses, maximize human immune function, and minimize health risks from mold, yet uncertainties exist about typical RH levels in offices globally and about the potential independent impacts of RH levels on workers' health. To examine this, we leveraged one year of indoor RH measurements (which study participants could view in real time) in 43 office buildings in China, India, Mexico, Thailand, the United Kingdom, and the United States, and corresponding self-report symptom data from 227 office workers in a subset of 32 buildings. In the buildings in this study, 42% of measurements during 9:00 - 17:00 on weekdays were less than 40% RH and 7% exceeded 60% RH. Indoor RH levels tended to be lower in less tropical regions, in winter months, when outdoor RH or temperature was low, and late in the workday. Furthermore, we also found statistically significant evidence that higher indoor RH levels across the range of 14%-70% RH were associated with lower odds of reporting dryness or irritation of the throat and skin among females and unusual fatigue among males in models adjusted for indoor temperature, country, and day of year.

The Effects of Ventilation and Filtration on Indoor PM2.5 in Office Buildings in Four Countries

Fine particulate matter (PM_2.5) is an airborne pollutant associated with negative acute and chronic human health outcomes. Although the majority of PM_2.5 research has focused on outdoor exposures, people spend the majority of their time indoors, where PM_2.5 of outdoor origin can penetrate. In this work, we measured indoor PM_2.5 continuously for one year in 37 urban commercial offices with mechanical or mixed-mode ventilation in China, India, the United Kingdom, and the United States. We found that indoor PM_2.5 concentrations were generally higher when and where outdoor PM_2.5 was elevated. In India and China, mean workday indoor PM_2.5 levels exceeded the World Health Organization's 24-hour exposure guideline of 25 µg/m³ about 17% and 27% of the time, respectively. Our statistical models found evidence that the operation of mechanical ventilation systems could mitigate the intrusion of outdoor PM_2.5: during standard work hours, a 10 µg/m³ increase in outdoor PM_2.5 was associated with 19.9% increase in the expected concentration of indoor PM_2.5 (p<0.0001), compared to a larger 23.4% increase during non-work hours (p<0.0001). Finally, our models found that using filters with ratings of MERV 13-14 or MERV 15+ was associated with a 30.9% (95% CI: -55.0%, +6.2%) or 39.4% (95% CI: -62.0%, -3.4%) reduction of indoor PM_2.5, respectively, compared to filters with lower MERV 7-12 ratings. Our results demonstrate the potential efficacy of mechanical ventilation with efficient filtration as a public health strategy to protect workers from PM_2.5 exposure, particularly where outdoor levels of PM_2.5 are elevated.

Decoupling Office Energy Efficiency From Employees' Well-Being and Performance: A Systematic Review

Energy efficiency (i.e., the ratio of output of performance to input of energy) in office buildings can reduce energy costs and CO₂ emissions, but there are barriers to widespread adoption of energy efficient solutions in offices because they are often perceived as a potential threat to perceived comfort, well-being, and performance of office users. However, the links between offices' energy efficiency and users' performance and well-being through their moderators are neither necessary nor empirically confirmed. The purpose of this study is to carry out a systematic review to identify the existing empirical evidence regarding the relationships between energy-efficient solutions in sustainable office buildings and the perceptions of employees' productivity and well-being. Additionally, we aim to identify relevant boundary conditions for these relationships to occur. A systematic literature search of online databases for energy efficiency literature (e.g., Environment Complete, GreenFILE), employee literature (e.g., PsycINFO, Business Source Complete) and general social science literature (e.g., Academic Search Complete) yielded 34 empirical studies. Also, inclusion and exclusion criteria were set. The results suggest that it is possible to decouple energy costs from organizational outcomes such as employee well-being and performance. Also, they indicate the existence of moderators and mediators in the relationship between green office building solutions and well-being/performance. Directions for future research and the implications for practice considering different stakeholders interested in implementing green building solutions, adopting energy-saving measures in offices, and improving employees' functioning are suggested.

Perceived Indoor Environment and Occupants' Comfort in European "Modern" Office Buildings: The OFFICAIR Study

Indoor environmental conditions (thermal, noise, light, and indoor air quality) may affect workers' comfort, and consequently their health and well-being, as well as their productivity. This study aimed to assess the relations between perceived indoor environment and occupants' comfort, and to examine the modifying effects of both personal and building characteristics. Within the framework of the European project OFFICAIR, a questionnaire survey was administered to 7441 workers in 167 "modern" office buildings in eight European countries (Finland, France, Greece, Hungary, Italy, The Netherlands, Portugal, and Spain). Occupants assessed indoor environmental quality (IEQ) using both crude IEQ items (satisfaction with thermal comfort, noise, light, and indoor air quality), and detailed items related to indoor environmental parameters (e.g., too hot/cold temperature, humid/dry air, noise inside/outside, natural/artificial light, odor) of their office environment. Ordinal logistic regression analyses were performed to assess the relations between perceived IEQ and occupants' comfort. The highest association with occupants' overall comfort was found for "noise", followed by "air quality", "light" and "thermal" satisfaction. Analysis of detailed parameters revealed that "noise inside the buildings" was highly associated with occupants' overall comfort. "Layout of the offices" was the next parameter highly associated with overall comfort. The relations between IEQ and comfort differed by personal characteristics (gender, age, and the Effort Reward Imbalance index), and building characteristics (office type and building's location). Workplace design should take into account both occupant and the building characteristics in order to provide healthier and more comfortable conditions to their occupants.