Deep Cleaning during the Covid Pandemic

Prepared by Spencer and Fry, Conservation specialists, November 2020

 Relative Humidity and Temperature

In terms of surface persistence, increased temperature and relative humidity do reduce the half-life of the SARS-CoV-2 virus, (a low RH is below 40%).

Above 60% there is an increased risk of mould and related illnesses.

Any air conditioning, humidification or heating should be directed away from people.

Changes to environmental conditions can have a seriously damaging impact on collections and historic interiors, and so should not be implemented without the advice of a conservator, and the environment should be maintained between 40-60% RH.

The Academy of Medical Sciences report on preparing for winter 2020/21 (The Academy of Medical Sciences, 2020) states that in most indoor environments the virus is “unlikely to persist in the air at a level that poses a risk for more than 30 minutes after an infected person leaves.”

We hope that more published research will be available to share soon, and there is more advice on the Historic England website. Guidance from Historic England on Cleaning Historic surfaces:


National Trust Manual of Housekeeping – 2011

SEMD Advice on Reopening Museums – Reopening Museums Toolkit

ICON ‘Waking Up’ Collections: A Post-lockdown Guide

Historic England Guidance for Reopening Heritage Locations

Centres for Disease Control and Prevention

Guidance from Historic England on Cleaning Historic surfaces

Conservation Advice on the SEMD website

Government advice on cleaning work areas during Covid 19

Government advice on cleaning during Covid 19,the%20cleaning%20guidance%20above

Information about Benchmarks in Collections Care 2.1

Advice about vacuuming

Collection Care Guidance for Museums and Historic Properties during the Covid-19 Crisis Guidance note prepared by Claire Fry ACR, Preventive Conservation Consultant, Spencer & Fry

Guest Blog about mould in museum Collections on the PEL website; Finch, L. Help, I have mould! Conservation and Cleaning



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