Humans are one of the main sources of microbes in buildings. On average, one person releases about 37 million bacteria into the air per hour. The fate of these bacteria depends on the type of indoor surfaces and heating, ventilation, and air-conditioning. Due to concerns over infection control, healthcare facilities are wary of exposed wood in mass timber construction. Therefore, researchers from the University of Oregon’s Institute for Health in the Built Environment studied the microbial activity of wood, including both finished and unfinished cross-laminated timber (CLT). They found that raw, unfinished wood uniquely “fosters beneficial microbes while inactivating pathogens.” This was also true for softwood species, such as Douglas fir, spruce, pine, and larch. However, wood loses its amazing ability to buffer humidity, exhibit natural antimicrobial activity, and selectively support beneficial microbes as soon as a synthetic sealer is applied.
This document is available as a free download. See page 21, for a summary of the antimicrobial activity of wood in indoor environments.