Relative humidity in workplace can impact employee health

We all know that humidity can have an impact on our hair and skin, but a new study from researchers at Baylor College of Medicine and the University of Arizona suggests that relative humidity levels in the office setting also can have an impact on stress and potentially even sleep quality. The research was published recently in the journal Indoor Air.

According to Dr. Bijan Najafi, professor in the Michael E. DeBakey Department of Surgery at Baylor and director of clinical research in the division of vascular surgery and endovascular therapy, the relationship between office humidity levels and health can cost the employer in terms of productivity and sick leave. He and fellow researchers wanted to understand the impact that relative humidity has on health and well-being in real-world conditions.

The study is part of the “Wellbuilt for Wellbeing” project, funded by the United States General Services Administration and led by principal investigator Dr. Esther Sternberg, director of the UArizona Institute on Place, Wellbeing, & Performance and research director of the Andrew Weil Center for Integrative Medicine at the UArizona Health Sciences.

“It has been exciting to work on this project that is providing the evidence for design of healthy office spaces with the potential to affect the lives of millions of office workers and beyond,” Sternberg said. “This is the future of integrative health – to design and operate buildings that support health and well-being.”

Researchers gathered data from 134 individuals from four federal buildings across the country. Participants completed questionnaires on demographics, medical history and measures of actual and perceived stress and comfort as well as the Pittsburgh Sleep Quality Index. They wore a chest sensor that monitors heart rate and physical activity for three consecutive work days and two nights. Researchers also took continuous measurements of relative humidity at the workplace based on the 30 to 60% range for thermal comfort established by the American Society of Heating, Refrigerating and Air-Conditioning Engineers Standard 55-1989 and tracked participants’ proximity to the relative humidity measures using calendar information, recorded logs and floor plan coding. They categorized participants into three groups based on the range in which the majority of their relative humidity measurements fell:

1. Dry – less than 30% relative humidity
2. Comfort - between 30 and 60% relative humidity
3. Humid – more than 60% relative humidity

Researchers found that participants in the dry and humid group experienced 25% and 19% higher stress responses, respectively, compared to those in the comfort-humidity group. The stress response data also suggest the potential for an optimal range for relative humidity, even narrower than the current standard. Researchers also found an indirect relationship between relative humidity and objectively measured sleep quality.

According to Baylor experts, there are strategies to alleviate the effects of dry air:

• If you are in a dry indoor condition, take “micro-breaks” every 15 to 20 minutes and spend 30 seconds looking away from your computer. Blink repeatedly to maintain and rebuild the tear film on your eyes.
• Drink water regularly throughout the day – small changes in the body’s water balance has been associated with increased fatigue and reduced concentration.

Najafi, who also is the senior author of the paper, noted that because this was an observational study, additional interventional studies are needed to understand these relationships even further.