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A Method to Test the Efficacy of Handwashing for the Removal of Emerging Infectious Pathogens
Published on: June 7, 2017
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Quantifying the Viral Reduction Achieved Using Ash and Sand as Handwashing Agents
Winnie Zambrana1, Jingyan Tong1, Claire E Anderson1
1Department of Civil and Environmental Engineering, Stanford University, Stanford, California.
The American Journal of Tropical Medicine and Hygiene
|December 19, 2022
Summary
Washing hands with ash or sand can reduce viruses, but soap and water is more effective, especially for longer handwashing durations. Further research is needed for real-world applications.
Area of Science:
- Public Health
- Microbiology
- Environmental Science
Background:
- The World Health Organization (WHO) recommends 20-40 second handwashing with soap and water.
- Ash and sand are used as handwashing agents in areas lacking soap, but their efficacy is understudied.
Purpose of the Study:
- To quantify virus removal by ash and sand as handwashing agents.
- To compare the efficacy of ash and sand to standard handwashing methods.
Main Methods:
- A volunteer study assessed log reduction values (LRV) for model viruses Phi6 and MS2.
- Six handwashing conditions were tested: ash/water, sand/water (5 and 20 seconds), soap/water, and water-only (20 seconds).
- Plaque assays measured infectious virus reduction.
Main Results:
- All 20-second handwashing methods exceeded the FDA's 2-log reduction criteria for both viruses.
- Soap and water showed significantly higher LRVs than ash or sand at 5 seconds.
- Water-only washing yielded a higher LRV than ash or sand for MS2.
Conclusions:
- Ash and sand can effectively reduce viruses but are less efficacious than soap, particularly for short durations.
- Real-world studies are recommended to further investigate ash and sand as handwashing agents.
