Sunday Longread: Hand sanitiser and soap usage during the pandemic will have real environmental impacts

Researchers from Trinity have quantified the effect new hygiene practices will have on our climate, and subsequently our health

A Trinity-led study has found that our increased use of hand sanitisers and soaps during the pandemic will have some knock-on effects on our climate. Hand sanitiser, which before March 2020 was mainly used only in hospitals and healthcare settings, suddenly became one of our most commonly reached for hygiene products, almost overnight. Many of us will remember the shortages of the product and restrictions on bulk buying it at the beginning of the pandemic. Two years on, sanitisers have now become a household necessity and their use is a part of most of our daily routines.

Hand sanitiser use and increased handwashing practices hold a vital role in disease prevention and have helped the public to slow the spread of Covid-19, and as a result, will have saved innumerable lives. Their ability to kill pathogens such as the coronavirus is of vital importance. But they do not come without costs, and Trinity scientists have been evaluating these in an environmental context. They have also evaluated the health impact that this climate impact may have.

The researchers found that the manufacture and use of hand sanitiser liquids and gels have added approximately 2% to our usual carbon footprint, a non-trivial figure. When this is put into a human health context, the study showed that their negative human health impacts may result in the loss of between 16 and 114 hours of life expectancy, based on a comprehensive disability-adjusted life years (DALYs) impact analysis. The overwhelming majority of human health impacts came from ozone layer depletion, and this was consistent across all sanitisers and soaps.

“There are several ways in which these increased hygiene practices have affected our planet.”

First author of the work and Associate Professor in the School of Dental Science, Dr Brett Duane commented: “Hand hygiene has certainly made a big difference in slowing the transmission of COVID-19 over the past two years, but this research—the first of its kind that assesses the use of sanitising gels and increased hand-washing practices in a way that clearly quantifies the impacts on human and planetary health—shows these practices do cause significant harm.”

There are several ways in which these increased hygiene practices have affected our planet. Firstly, it is clear that any level of increased handwashing will result in increased water usage. Sourcing and treating clean water to use for homes is energy-intensive and in general, we should aim to conserve as much water as possible.

As well as this, sanitising gels are normally alcohol-based. The alcohol components are carbon-intensive to produce, even before we factor in packaging and transportation emissions. As we are all familiar with, increased carbon emissions feed into the issue of global warming. The work by Trinity researchers published in the Environmental Sciences and Pollution Research journal is the first of its kind to evaluate this environmental and health impact on a macro scale.

In terms of soap, for liquid soap the vast majority of the climate and health impact came from the ingredients, while bar soap’s harms are predominantly related to the manufacturing process.

The researchers modelled the impacts of the UK population adopting each of the following four hand-washing practices over the course of one year: ethanol-based sanitising gel, isopropanol-based sanitising gel, liquid soap and water, and bar soap and water, evaluating the subsequent environmental and health impacts in areas like climate change, freshwater ecotoxicity, ozone layer depletion,  and water use.

They found that isopropanol-based sanitising gels had the lowest impacts virtually across the board, with four times lower climate impact than liquid soap hand washing (producing an equivalent to 1,060 million Kg CO2 compared with 4,240 million kg CO2). Isopropanol-based sanitising gels would cause a per person loss of 16 hours in disability-adjusted life years (a small reduction in life expectancy) if collectively used by the population of the UK for one year. However, liquid soap and hand-washing approaches would cause a per person loss of 114 hours, which is almost five days in life expectancy, compared to just 43 hours for bar soap.

“From a purely health-related standpoint, it is generally recommended only to use hand sanitiser when washing your hands with soap and water is not possible.”

On the other hand, many public health experts have consistently said that soap and water are much more effective at slowing the spread of pathogens than hand sanitiser. In general, sanitising gels are less effective when hands are particularly dirty, are less capable against particular pathogens such as noroviruses, and cannot remove harmful chemicals. From a purely health-related standpoint, it is generally recommended only to use hand sanitiser when washing your hands with soap and water is not possible.

Duane says the Trinity study makes clear the need for more environmentally friendly hygiene practices, to protect aspects of public health outside of Covid-19. “Importantly, the work shows that sanitising gels cause less harm than soap-and-water practices, with isopropanol-based gels in particular leaving a relatively lower impact. That is useful information for reducing further damage but the work also underlines the need for new gels that are more environmentally friendly.”

Lucy Fitzsimmons

Lucy Fitzsimmons is the SciTech co-Editor of Trinity News, and a Junior Sophister student of Chemical Sciences.