Time to ‘spruce up’ your pathogen safety measures with wooden surfaces?

Panshanger Park woodland, image by Tim Sandle.

Viruses, including the coronavirus that causes COVID-19, can get passed from person to person via contaminated surfaces. Depending on the type of surface, enveloped viruses, like the coronavirus, can survive up to five days on surfaces; whereas, nonenveloped viruses, including the enteroviruses linked to the common cold, can survive for weeks even if the surfaces are disinfected.

Healthcare facilities have for a long time been concerned about surface transmission and this has been met by the use of different surface finishes and disinfection regimes.

Over the past few decades wooden surfaces have been removed from clinical practices, with such surfaces being considered challenging to disinfect. In some cases, antimicrobial surfaces have been installed, such as those based on copper or with silver ions added.

However, it appears that wood might not be the unsuitable surface for wood has been found to possess anti-viral properties. Wood has natural antiviral properties that can reduce the time viruses persist on its surface — and some species of wood are more effective than others at reducing infectivity.

New research has considered for how long enveloped and nonenveloped viruses remained infectious on the surface of six types of wood: Scots pine, silver birch, grey alder, eucalyptus, pedunculate oak and Norway spruce.

To determine viral activity, the virologists flushed a wood sample’s surface with a liquid solution at different time points and then placed that solution into a Petri dish that contained cultured cells.

After incubating the cells with the solution, the scientists measured the number of cells (if any) infected with the virus.

Results from the study with an enveloped coronavirus showed that pine, spruce, birch and alder need one hour to completely reduce the virus’ ability to infect cells, and with eucalyptus and oak needing two hours.

Overall, pine had the fastest onset of antiviral activity, beginning after five minutes. Spruce came in second, showing a sharp drop in infectivity after 10 minutes.

For a nonenveloped enterovirus, the researchers found that incubation on oak and spruce surfaces resulted in a loss of infectivity within about an hour, with oak having an onset time of 7.5 minutes and spruce after 60 minutes. Pine, birch and eucalyptus reduced the virus’ infectivity after four hours, and alder showed no antiviral effect.

Across both types of virus, spruce emerges as the best ‘all-rounder’.

The research appears in the journal ACS Applied Materials & Interfaces, titled “Tree Species-Dependent Inactivation of Coronaviruses and Enteroviruses on Solid Wood Surfaces..”