Human health and productivity outcomes associated with indoor air quality: a systematic review

Abstract

Characteristics of the indoor environmental quality directly impact humans’ ability to lead healthy and productive lives. We estimated the effects of changes in indoor air quality (namely through indoor ventilation rates and carbon dioxide levels) on health, performance, and productivity outcomes in students (primary, secondary, and university), laboratory test subjects, and workers. For this systematic review, we searched PubMed, from database inception to October 15, 2020, for relevant studies in any classroom, lab, and labor environment at any level of indoor air quality. No restrictions on language, workers’ health status, or study design were applied. Good and bad indoor air quality was defined using American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) standards. We excluded studies that calculated effects focusing on air temperature, humidity levels, systematic reviews on similar topics to avoid duplication, and any grey literature. Of 101 reports identified through our systematic search, 42 studies conducted in 10 countries and 3 continents, including 6,850 subjects were eligible for analysis. Our review showed that individuals exposed to indoor air quality settings above ASHRAE minimum standards (defined as ventilation rates 17 CFM per person and Carbon Dioxide (CO2) steady states of 1000 parts per million (ppm)) were more likely to experience increased poor levels of health, performance and productivity under these conditions. Overall, this analysis includes a variety of populations, exposures, and occupations to comply with a wider adoption of evidence synthesis but resulted in large heterogeneity. Poor indoor air quality has important human health, performance, and productivity outcomes and should be recognized as a public health problem. Inversely, improved indoor environmental conditions delivered through enhanced ventilation strategies should be considered a health, performance, and productivity opportunity for both students and workers. This study addresses these areas of concern and opportunity. However, given the lack of standardized methodologies, results reporting criteria across conducted air quality analyses, and a lack of international case studies, a concerted global effort is needed to conduct and compare research with standardized metrics. Furthermore, a majority of studies are conducted in school classrooms or laboratory environments or provide no remuneration to incentivize good performance - a condition not reflective of real-world office settings. To better understand the implication on office workers, additional field research can serve to enhance our understanding of indoor environmental factors on employee health and productivity in a setting where remuneration incentives may impact performance.