Hi,

It is worth remembering that all soap used to be made with wood ash, which has always been the source of lye. The main difference is that soap includes animal fat.

Many of the relevant papers talk about washing with "soil", but I think the key substance here is pure clay, which is dug out of the subsoil and is free from biological or chemical contamination. I am certain that there are scientific papers on this, but I did not have time to find them just now.

I like to mix ash and clay, roughly half and half (plus the amount of water necessary to make a paste), which is very pleasant for hand-washing.

One other substance to keep in mind is the same person's urine, with the key ingredient being urea.
link.springer.com/article/10.1007/s13555-021-00611-y
The person can urinate into a receptacle, introduce their hands into the liquid, and rub the hands together for an adequate amount of time. Then they can rinse with water. 

Some good relevant links that I found:
www.engineeringforchange.org/news/places...ve-prevent-covid-19/
www.ircwash.org/sites/default/files/ash_...for_hand_washing.pdf

We also need to be aware that companies that make soap spend large amounts of resources to lobby for its use, so we also need to sort out the science from the lobbying.

Best wishes,
Chris Canaday

Dear SuSanA Member 
Mr Chaingaa: 
It's true we can use wood Ash for hand-wash and many other cleaning, cooking eating utensils.
Even cow-dung cakes when used as cooking fuel, generate Ash, this too can be used.
This has been a standard practice,  in many rural homes.
In order the utensil are not scratched while washing, can use a fine sieve, and the coarse material mixed with cow-dung is used for coating floors in front of hut- homes
Well wishes 

Prof Ajit Seshadri
Vels University Chennai India and
Head Environment,  www.vigyanvijay.org 

You can use ash to wash hands whenever you don't have soap - Sylvia Masebo (Zambia's Minister of Health on the Main News on 15th February 2023.

Zambia, like all countries, is promoting accessing to basic hygiene service ie availability of a handwashing facility on premises with soap and water. This is also buttressed in the country's National ODF 2030 Strategy. 

However,  World Health Organization  like the minister, did provide seemingly contradictory guidance in 2020 at the advent of  #covid19pandemic  - that ash should be considered as an alternative to soap in low low income settings since it raises the pH which inactivate pathogens. Article here  lnkd.in/dyrZDTes . Compounding to this, ash isn't only known to be used for handwashing in poor settings but also dishwashing, teeth brushing and cooking (to reduce cooking time in beans and okra). This is an immemorial custom common in most African settings.

1. Arising from this seemingly contradictions, doesn't it then mean that there's a lot and urgent need to harmonize the guidance given to end users?
2. If ash can be used in dishwashing, teeth brushing, cooking etc, are there conclusive researches not only is ash's efficacy in handwashing but also in all those other areas?

Thanks

washing with ash removes dirt, oil, and grease which removes almost 90% of bacteria. moreover, it would be useful if you are not dealing in an area full of harmful bacteria and viruses as it doesn't pollute water as much as soap does. 

I am glad to see this topic come up. I conducted the research in a paper cited earlier in this thread where we examined whether the likelihood of diarrhea was different for households relying on soap versus ash:

Title: Association between Moderate-to-Severe Diarrhea in Young Children in the Global Enteric Multicenter Study (GEMS) and Types of
Handwashing Materials Used by Caretakers in Mirzapur, Bangladesh. 
Authors: Baker, K.K., Dil Farzana, F., Ferdous, F., Ahmed, S., Kumar Das, S., Faruque, A.S.G., Nasrin, D., Kotloff, K.L., Nataro, J.P., Kolappaswamy, K., Levine, M.M.,
Year: 2014.
Am. J. Trop. Med. Hyg. 91, 181–189.  doi.org/10.4269/ajtmh.13-0509

One piece of data that gets overlooked in that paper is that the epi data was followed up with environmental microbiology bench experiments where i prepared an ash and water suspension as described by Bangladeshi women and then spiked it with different types of bacterial pathogens, like Shigella, Vibrio cholera, and ETEC. I was able to isolate a handful of pathogenic bacteria in high dose bacteria concentrations out to 15 or 20 seconds, but nothing (including high pH loving vibrios!) survived for longer time points. As proposed earlier, the pH 9-10 of such a solution is so caustic that bacteria generally cannot survive. It destroys the lipid structure in the cell wall.

Given what we know about the survival of many viruses in the environment, it is reasonable to hypothesize that yes ash is fairly effective at destroying viruses or the molecular binding structures on their surfaces as well. Maybe I can motivate a student to repeat some of those experiments with the viruses we have in house...

That does not make it pleasant or ideal to wash with, or mitigate the chemical exposure issues, so I endorse the strategies that recommend it in situations where washing might not happen at all, or with water only.

Post-comment edit
To my knowledge the majority of ash users are rural, as noted by a previous author, and the sources are wood, brush, and cow dung. Exposure to man-made chemicals, lead, etc from such burn sources seems very unlikely.

This has been an interesting thread to read.

Allow me to add that quite a good number of people in urban communities use soap either in its liquid or solid form, However, many communities in rural areas can not access or afford soap. The SAGE journal documents some research on handwashing practices in Bangladesh and elsewhere have actually shown that ash can be a low-cost alternative to soap. Bangladeshi fieldwork carried out in 2007 found that 13% of people in the sample used ash or soil (which brings about a whole other discussion) to wash their hands after defecating, compared to 19% who used soap. Organizations like UNICEF have recommended that people without soap wash their hands with ash. The Cochrane Library early this year in April did a study to know whether people who use ash for hand cleaning were more or unlikely to catch infections than people who use soap. The study investigated children who had been to the hospital with diarrhoea compared with children who had not. The study focused on handwashing in children. Most families that used ash for hand cleaning made a similar number of hospital visits for children with diarrhoea as those families that used soap. 

Traditionally within the African setting, soil, ash, and salt have been used as both mechanical and chemical forms of neutralizing contaminants on dirty hands and surfaces.   The premise of the effectiveness of such materials assumes that households will obtain the soil, ash, and salt from uncontaminated sources.  The availability of these alternative methods may be limited to people living in informal urban settlements areas but not in rural areas.

Regards,
Chaiwe

Hi,

The statement in our post that says 'Be aware that handwashing with ash does not feel very nice and does not leave hands feeling and smelling nice in the way that soap does, as such promoting ash may actually discourage people from practicing handwashing' is based on research that I and others have done in several countries exploring soap products and ash. This includes work done in DRC, Ethiopia, and Nigeria - all settings where ash is commonly promoted by NGOs and quite widely used in some regions. This sentiment reflects the sentiment of populations who, across these countries, consistently rank ash as the least desirable option for handwashing. The fact that it continues to be used widely is much more a factor of poverty and inequality. In fact people often directly said that ash is perceived as something only poor people would use - a label that understandably they did not wanted to be associated with.

In general I am not familiar with organisations promoting the use of soap and discouraging the use of ash. In most cases handwashing with soap is promoted and organisations explain that if soap is scarce ash can be used instead. However at the moment I think this is an imperative to actively encourage people to use soap where possible because we know that it can effectively destroy and remove SARS-CoV-2 from hands. While it is plausible that ash may be able to do the same we have no evidence to suggest this at the current time.

I hope that helps

Sian White

Research Fellow
Environmental Health Group - Faculty of Infectious and Tropical Diseases London School of Hygiene and Tropical Medicine

Find out more about the Environmental Health Group at: ehg.lshtm.ac.uk Find out more about the Health in Humanitarian Crises Centre at: crises.lshtm.ac.uk

Hi Elisabeth,

sodium hydroxide is caustic soda or lye. Lye dissolves greases. White wood ash contains potassium carbonate, or potash, along with calcium hydroxide, but very little if any sodium hydroxide. By adding water to white wood ash, the calcium hydroxide and potassium carbonate react, forming caustic potash (ash lye, potassium hydroxide) and calcium carbonate (please somebody correct me if I'm wrong, I'm not a chemist!).

On this basis I have always assumed that handwashing with ash and water means handwashing with ash lye. I wash my hands with wood ash, which is particularly effective at removing greases and hard-to-remove dirt. Ash will remove just about anything from hands, and it certainly is not painful to use and it doesn't burn skin. Well, not mine anyway...

I'm asking whether it's appropriate for people from the developed world who like the smell and feel of soap to impose their paradigms on those with different practices...  Habits are also influenced by tradition and availability. If someone washes their hands effectively with wood ash and has always done so, because they are happy with that practice and use their own resources, is it right for someone to come along and say "you should use soap, it will feel nice on your skin and make you smell nice."?

cheers
Dean

Thanks for the interesting forum posts. The word "lye" was new to me and I had to look it up. If others also didn't know what it is, here is a quick result from Google search:
Turning your wood ash into lye for soap making

It says there:

Lye (sodium hydroxide) is formed when wood ash (which is mostly potassium carbonate) is mixed with water. The mixed solution is extremely alkaline and if it comes in contact with your skin, it begins to absorb the oils and turns your skin into soap. It's pretty painful so before I ever begin, I make sure that I have vinegar nearby to neutralize the burn if the solution does happen to come in contact with my skin. I also wear rubber gloves and goggles in case there is any splash back during the mixing process.

I have the feeling that there is confusion in some of the statements: the original question was about handwashing with ash. Handwashing with ash lye is a bit different, isn't it? If ash lye is used to make soap (like that article above explains) then it's a different story again.

I do wonder how widespread the handwashing with ash or ash lye is these days. Is it only practiced in rural areas where people cook with firewood, or also in more urban areas (people cooking with coal?)). Is it common?

Furthermore, Dean wrote: 

Sian Whites statement "handwashing with ash does not feel very nice and does not leave hands feeling and smelling nice in the way that soap does" do not help either. Advice should be authoritative and objective.

I disagree with Dean and find that Sian's statement is perfectly valid. Handwashing has a lot to do with habits, and habits are influenced by feelings, smells, aspirations and so forth.  So if handwashing with ash becomes a deterrent to handwashing at all then we have a problem. 

Regards,
Elisabeth

When growing up in rural Kenya we were always advised to use hot ash for disinfecting latrines. The high temperature played some role in killing the pathogens. Hot ash, though, shouldn't be used to wash hands as it can lead to burns. Cold ash may do due to the high pH. Caution should, however, be taken to avoid bruising hands with the coarse particles by applying the ash directly to hands. The best approach would be to mix the ash with water in a bucket and allow it to settle. After settling, clean  water can be decanted and used for washing hands.

Coronavirus are wrapped in a lipid (oil) envelope, therefore ash lye should be just as effective as soap at breaking this down. Not sure why Sian White would assume that ash only works by abrasion. The lye in ash dissolves oils and being a concentrated alkali is also a disinfectant. Perhaps a chemist could chip in to this discussion?

Juan Smulders states that "ash can kill germs (less effectively than soap of course)". Noting how caustic ash is, it should be far more effective than soap at disinfecting. Juans statement comes across as a subjective impression. Sian Whites statement "handwashing with ash does not feel very nice and does not leave hands feeling and smelling nice in the way that soap does" do not help either. Advice should be authoritative and objective. For example: Handwashing with ash does not bear the risk of contracting soil-transmitted pathogens unless contaminated soil is mixed with the ash.

Exposure to heavy metals in the ash depends on the particular timber treatment used. Chrome-copper-arsenic treatments will leave arsenic, chrome and copper in the ash (heavy metals). But these are not cadmium, mercury or lead oxides, and I very much doubt that washing hands with the resulting ash will cause an accumulation of arsenic, chrome or copper in the body. I'd be more worried about exposure from the fumes when burning CCA treated wood. Then there is creosote treatment (e.g. in railway sleepers). This will not remain in the ash and although the smoke might contain some toxins resulting from incomplete combustion, the ash will not contain toxins or heavy metals. Then there is boron treatment, which will result in ash containing small quantities of boron. Even better for washing hands and with no consequence. Generalisations that "treated" timber will produce toxic ash are not helpful.

cheers
Dean

Washing, cleaning, decontamination, and disinfection do not have equal meanings. Washing means exposure to cleaners. Specifically, water cleaning means removing physical and visible dirt, particularly with clean water. Decontamination means removing hazard agents, for example, cleaning the surface with water and detergent or soap.

Disinfection means removing infection agent by killing biological pathogen or removing chemical hazard agents or enabling them to cause a hazard and reproduce (biological) or removing by diluting (chemical).

About ash application ash a cleaner," Wood ash and natural lye have been widely used in villages for centuries as a cleaning material in the form of soaps by being mixed  with natural oils in certain amounts."    *
Wood ash can be directly used in its dry form for cleaning by scrubbing as well as in the form of lye through mixing it with water ".
Many of the cleaning products we use in our houses today contain chemically reactive and toxic ingredients. This is a big risk to take for the health of our bodies and our planet since we directly inhale these chemicals and they also pollutes the soil and water.

*  ecovillage.org/solution/wood-ash-as-a-na...l-cleaning-material/

 So ash could be a suitable alternative  (cleaner not disinfectant) when other cleaning agents are not available particularly in emergency situation or absence or shortage.

Mohammad