World Health Organization Updates COVID-19 PPE Guidelines to Include New Decontamination Method: Methylene Blue + Light

SEATTLE – The World Health Organization (WHO) just added Methylene Blue and Light as a supported Personal Protective Equipment (PPE) decontamination method in the “Rational use of personal protective equipment for COVID-19 and considerations during severe shortages” interim guidelines.

Making its first update to these PPE guidelines since April 2020, the WHO provided updated strategies for optimizing PPE use by health workers caring for patients with suspected, probable, and confirmed COVID-19, including a new section for PPE decontamination and reprocessing considerations.

The updated guidelines now state:  

MBL (Methylene Blue and Light) and DH (Dry Heat) were applied to respirators and medical mask materials to test inactivation of SARS-CoV-2 and surrogate coronaviruses. The study found that both MBL and DH consistently killed SARS-CoV-2, with some heterogeneity in DH values. The findings suggest MBL could potentially be developed as a new reprocessing method.

The Development of Methods for Mask and N95 Decontamination (DeMaND) Study, cited by the WHO, sought to determine simple, efficient, and inexpensive methods to reprocess SARS-CoV-2-exposed medical masks and respirators. The study showed for the first time how Methylene Blue (MB), a common light-activated dye (LAD), can be applied to masks and other personal protective equipment (PPE) to both decontaminate coronavirus-infected PPE and provide continuous inactivation of the virus.

The DeMaND Study was led by Singletto co-founders Drs. Thomas Lendvay and James Chen in collaboration with esteemed colleagues in a consortium of worldwide labs assembled through the WHO COVID-19 Task Force. Singletto has continued research into this breakthrough method, now conducting five follow-up studies in its Singletto labs around North America.

Drs. Lendvay and Chen, along with Singletto co-founder Dr. Tanner Clark, Virologist Dr. David Evans, Arbovirologist Dr. Chris Mores, Immunologist and Virologist Dr. Michael Gale, and Photochemist Dr. Belinda Heyne are leading the research – working to develop further technological advances that will make our healthcare community, and community at large, better prepared to safely fight pathogens.

About Singletto

Singletto provides the novel solutions needed to face the important medical and health challenges of today and tomorrow. Singletto builds pathogen-destroying singlet oxygen solutions to help you feel free to live well. Singletto works with healthcare-focused and general consumer brands and manufacturers to provide solutions for their existing and future products, technology, and systems by licensing its proprietary OxyFence™ technology. Singletto is seeking EUA (Emergency use Authorization) approval for certain use-cases of this technology for immediate COVID-19 relief.

To view the WHO Guidelines, visit:

For more information about the DeMaND Study, visit

For more information about Singletto, visit

Singletto Contact:


November 15, 2021
Protective Dye Methylene Blue Plus Light Proven to Inactivate "Hard-to-kill" Norovirus

Singletto's Dr. Lendvay contributed to a New MB Study


May 22, 2021
Infection Control & Hospital Epidemiology Publishes Drs. Lendvay, Chen, et al. WHO-led DeMaND Study

The Infection Control & Hospital Epidemiology medical journal has published the peer-reviewed DeMaND study. Singletto’s Dr. Tom Lendvay served as Lead Author.


May 20, 2021
Top Doctor 2021: Singletto’s Lendvay Named by Seattle Magazine

Dr. Thomas Lendvay, Singletto’s Co-Founder and Chief Medical Officer was just named a “Top Doctor” by Seattle Magazine.


March 25, 2021
A Moral Obligation: Why the Former Providence President Wants Singletto Tech Out Now

Mike Butler spent over two decades in leadership at Providence Health, growing such from a $2 billion organization to $25 billion. Upon recently retiring, Mike knew he wanted to find ways to continue impacting the lives and health of others. Now at Singletto, Mike is on a mission to bring the novel Singletto technology to market – in healthcare and beyond. But, it’s not just a passion project … upon learning about the technology, Mike felt a moral obligation to get it in as many hands as possible. More with recently retired Providence Health President Mike Butler…


February 25, 2021
Hospital News: Light kills. SARS-CoV-2, That Is.

Singletto Advisor Dr. Belinda Heyne shares DeMaND study results on Hospital News.

Lacey Duffy

Customer Experience
February 12, 2021
CBC: This simple mix of dye and light could decontaminate masks for reuse

Dr. Belinda Heyne was recently featured in a CBC piece covering the DeMaND study’s findings and the life-giving potential of dye and light.