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Evidence based application of upper room UVGI under resource limited conditions

By Edward Nardell, MD Moderator | 10 Jul, 2015

I have been waiting a long time to launch a discussion on the evidence-based application of upper room UVGI under resource limited conditions. This coincides with 3 happenings:
1) the publication of the following paper - electronically for now - but in print soon. I cannot post a PDF, but individuals can ask me for copies. I will accumulate requests and reply at one time.

Mphaphlele M, Dharmadhikari AS, Jensen PA, Rudnick SN, van Reenen TH, Pagano MA, Leuschner W, Sears TA, Milonova SP, van der Walt M, Stoltz AC, Nardell EA. Institutional Tuberculosis Transmission:
Controlled Trial of Upper Room Ultraviolet Air Disinfection - A basis for new dosing guidelines. Am J Resp Crit Care Med 2015 (in press, to be published with an editorial).

2) a USAID sponsored meeting organized by URC and PIH in Bethesda in May "Toward International Guidelines for upper room UVGI"

3) the imminent release of South African guidelines for upper room UVGI - written in cooperation with South African efforts.

Topics will include indications and indications for upper room UVGI, barriers to implementation and maintenance, safety, efficacy and new dosing guidelines - plus any other topics you raise

Stay tuned.

Ed Nardell, MD



Urvashi Singh Replied at 9:47 AM, 10 Jul 2015

Dear Dr Nardell,
If you could kindly make all the three documents available,it would indeed
make a difference to those working with TB.
Thanks and Warm regards,

Tore Steen Replied at 9:49 AM, 10 Jul 2015

Thnak you. I should like to receive a copy of the paper by Mphaphlele et al, if possible.
Regards, Tore Steen

Tore Wælgaard SteenPublic Health SpecialistHealth Agency, City of OsloPO Box 47160506 OsloNorway

Vineet Bhatia Replied at 10:08 AM, 10 Jul 2015

Dear Ed,Request you to send me the documents as and when possible

Boniface Hakizimana Replied at 10:58 AM, 10 Jul 2015

This is very interesting dear Edward.

Should I have copies please?

Kind regards

Infection Control Coordinator
University Teaching Hospital of Butare
Centre Hospitalier Universitaire de Butare
Tel: (+250)788594903

En date de : Ven 10.7.15, Edward Nardell, MD via GHDonline <> a écrit :

Objet: Evidence based application of upper room UVGI under resource limited conditions

Grigory Volchenkov, MD Moderator Replied at 11:27 AM, 10 Jul 2015

Great initiative, Ed!

Please include me into the list


Joachim Okhifo Replied at 12:01 PM, 10 Jul 2015

Thanks Dr. Nardell for this wonderful initiative.
I will like to receive the papers.

Edward Nardell, MD Moderator Replied at 12:19 PM, 10 Jul 2015

Please do not request documents through GHDonline. Use .

I have only the UV publication. The SA Guidelines are not yet released and
there is no document from the Bethesda meeting.


Jude Beauchamp Replied at 1:18 PM, 10 Jul 2015

Hi Dr Nardell,
I am also very interested in those paper.
Thanks a lot

Edward Nardell, MD Moderator Replied at 4:35 PM, 10 Jul 2015

This is not working - for those requesting more information I do not see
your email addresses through GHDonline and cannot post the pdf on here.
You must send an email to and I can respond - cannot


Edward Nardell, MD Moderator Replied at 5:55 PM, 11 Jul 2015

UVGI #!: What are the barriers to applying upper room UVGI in resource limited settings?

We probably should start with a discussion of where to apply upper room UVGI and where not, but if there are barriers to its application, the rest is irrelevant. In my travels around the world, the major barriers that I have observed are the following:

1) Cost. While cost is always an issue in resource limited conditions it is important to understand that properly applied upper room UVGI is by far the most cost effective engineering intervention against TB transmission except for natural ventilation. While natural ventilation is great, where conditions are favorable, outside conditions change often and may not always produce effective indoor air disinfection. I colder climates windows are often closed at night, and increasingly in very hot climates, split system AC are being introduced into crowded clinics and waiting areas for comfort - but windows must be closed, and natural ventilation ceases - since split system UV provides no air changes. Recent advance in UVGI dosing strategies and technology have led to much more efficient upper room systems, and even more effective LED UV fixtures are only a matter of time - but are many years from reality at the moment. Grigory Volchenkov (Russia) and Paul Jensen (CDC) in an as yet unpublished study showed that upper room UVGI produced equivalent air changes about 9 times more cost efficiently than mechanical ventilation, and much cheaper than any of 3 room air cleaners tested.

2) Expertise/ proper dosing guidance. Until now, good evidence-based dosing strategies were lacking. NIOSH 2009 guidelines were evidence based, but not practical to implement since they called for producing certain average levels of UVGI irradiance in the upper room, but there were no way to predict that level before installing fixtures and no standard way of measuring average UV irradiance (more properly, average UVGI fluency rates from several fixtures in a room). However, based on the recently published study referred to in the previous blog, we are recommended simply 15-20 mW/m3 room volume total fixture output. The new South African Guidelines will recommend 20 mW/cm3, the high end of the range, because UVGI lamps lose some power over time. Dosing is based on the entire room volume because the larger the room volume, the greater the air that must be disinfected, and the more UVGI fluency rate needed. Using total UV fixture output means that manufactures MUST provide customers with that data for each fixture model sold - measured independently by a qualified lighting laboratory with the details of measurements provided. Manufacturers should also provide a single reference point measurement, such as uW/cm2 mid fixture at 1 m from the fixture, specifying the meter and detector used. This will assure consumers that the fixture is working as claimed. In a later blog I will discuss how total fixture UVGI output is measured by lighting laboratories.

Example of dosing. A room 5 m by 10 m by 3 m high has a volume of 150 m3. Providing 15 - 20 uW/cm2 total fixture output means that the room requires approximately 2.5 W total UV output. In our study half of our fixtures were more efficient, producing 0.49 W total output, while others were less efficient, producing 0.22 W total output. If the more efficient fixtures were used, 2.5 W requirement would call for 5 of the fixtures putting out 0.5 W each. If the less efficient fixture is chosen, twice as many - 10 fixtures would be required to deliver 2.5W. In another discussion I will introduce lower cost options, especially "eggcrate UVGI" if ceilings are high enough.

Two other requirements:
a) Fixtures should be placed so as to produce the longest ray length possible in a room. If a room were twice as long as wide, that means placing fixtures on the short wall to take advantage of the longer ray length. This is because UV rays are effective until they strike and are absorbed by walls or ceiling. Although diverging, the longer they travel before being absorbed by a surface, the greater the air disinfection. In a room twice as long as wide, the germicidal benefit of installation on the short wall for maximum ray length on average UVGI irradiance is not twice as great, but still beneficial. Windows and other obstacles may make it impossible to follow this guideline in every case.
b) Multiple UVGI fixtures should be placed to distribute UVGI irradiance as evenly as possible, but locations close to walls should be avoided due to wall absorption of lateral rays with reductions in average UVGI fluency rate. Good air mixing generally assures that all air in the room passes through the irradiated zones over and over again, but more even distributions have been shown to be more effective than uneven distributions. For example, it is better to place UV fixtures on opposite walls rather than on the same wall.

Air mixing. Upper room UVGI is properly called "UVGI-Air mixing systems" acknowledging the importance of air mixing. Upper room UVGI should rarely be installed in rooms without air mixing, ideally by low velocity ceiling fans, because they are inexpensive , reliable, and quiet. Speed and direction of paddle fans is not critical. Low velocity results in greater contact time for each pass through the irradiated zone, but higher velocity fans result in more frequent passes. Downward direction of airflow is often favored is summer and with very tall ceilings. Upward direction is favored in winter. We do not favor combining UVGI and fans in the same unit. Fans in such units are relatively ineffective compared to low velocity ceiling fans, and fixtures designed to incorporate fans are often more expensive while poor emitters of UVGI compared to simpler fixtures.

3) Good quality fixtures. Until recently small manufacturers made and sold UVGI fixtures designed to perform however the manufacturer chose. There were no performance standards. All UVGI fixtures with louvers for low ceilings that we have sen are highly inefficient. In order to prevent stray UVGI reaching occupants in the lower room, louvers absorb all but the most horizontal rays. One inefficient upper room fixture model we tested drew 110W at the wall (nominal power) and produced only 0.22 W. Another fixture we tested drew only 26 W (nominal power) from the wall, but produced 0.49 W. Because new application standards will be based on total UVGI fixture output, manufactures will be driven by the marketplace to build more efficient fixtures with high output.

4) Poor maintenance. More about this another time.

Much more to follow. Questions?


Dr Shanta Ghatak Replied at 4:27 AM, 12 Jul 2015

The concept and the accuracy of UVGIs cannot be more timely. Trained human resource is limited in areas where we need the fixtures. And cleaning mechanisms have been documented by me In some areas where the several UVGIs were being cleaned weekly and monthly with 70 percent alcohol and the lamps stopped working .......technicians and log books had been placed but turnover and lack of a constant supportive supervision for the lamps, lack of a logistical support in various areas of the cold countries really needs sufficient teeth now
Just thought of sharing something that I happened to have worked for a little while

Even the tools that I prepared for the risk assessment of nosocomial risk reduction for Tb infection control had a section on the UVGIs installation , changing lamps and cleaning of the lamps .....accountability being fixed on the infection control committees......


Sent from Shanta's iPad


S. Mehtar Replied at 5:35 AM, 12 Jul 2015

Registered Charity. Number: 2012/079606/08

Dear Ed
Well done Ed!! Excellent work to all the teams involved.
It is good so see some evidence at last and I think it makes more sense now that it did previously. However, despite all this wonderful work and excellent research, I am concerned about the very points Ed has blogged about such as the cost, the accurate dosage, maintenance etc. if this could be managed then I am sure there will be advantages to using UVGI in a closed room, with a definite air volume to be "sterilized", re circulated and exhausted, with good maintenance by either hospital staff or contractors. How one will manage this in clinics where there is much movement of persons through an open air flow system, needs careful consideration and investigation- incidently, these are also the areas where the most risk lurks, since there are undiagnosed and untreated cases of TB in such clinics. Finally, I look forward to reports or publications, of reduced TB transmission in healthcare facilities where upper room UVGI has been installed compared with those wards which do not have such amazing facilities
Apologies for my prolonged silence but I have away in Sierra Leone and so forth. But, I have been reading all the discussion with considerable interest.

Prof Shaheen Mehtar

Chair of Infection Control Network (ICAN)
MBBS, FRC Path (UK), FCPath (Micro) (SA), MD (Lon)

25th -28th Sept 2016: 6th ICAN Conference

Professor: Faculty of Medicine and Health Sciences
Stellenbosch University
PO Box 19063; Francie van Zijl Drive
South Africa
Tel: +27 21 938-5054; Faks / fax: +27 21 931-5065 / Mobile:+27 82 852 3697
e-mail: <mailto:>

Want to know what is happening in Africa in infection control?
Visit our website at www.icanetwork.co.za<http://www.icanetwork.co.za/>

chryssoula botsi Replied at 12:47 PM, 12 Jul 2015

Hi Dr Nardell
I am also very much interested on the papers. i would be gratefull if you can provide me with the pdfs
much obliged

Edward Nardell, MD Moderator Replied at 2:23 PM, 12 Jul 2015

As requested

Getu Terefe Replied at 3:53 AM, 13 Jul 2015

Dear Dr. Nardell,

I am an engineer working in infection control area and the papers on UVGI
would help me a lot if I get a copy.

Thank you so much in advance.

Edward Nardell, MD Moderator Replied at 6:52 AM, 13 Jul 2015

As requested

Thandeka Sacolo Replied at 7:23 AM, 13 Jul 2015

I am a regional TB/HIV infection control coordinator in one of the four regions in Swaziland. I am interested in the implementation of UVGI paper as I am from a country with poor coverage of installed UVGI lamps.

Edward Krisiunas Replied at 10:12 AM, 13 Jul 2015

Was a document supposed to be attached?

edward chilolo Replied at 10:49 AM, 13 Jul 2015

Dear Edward
Unfortunately I do not see the attached document as per my request Best regards,

Lucia Barrera Replied at 10:49 AM, 13 Jul 2015

Dear Dr Nardell
Please add me to the list of those interested in receiving the publications that you mentioned
Thank you very much for your important contribution to the evidence-based decisions

Lucia Barrera
TB laboratory consultant

Tarak Shah Replied at 10:54 AM, 13 Jul 2015

Dear Dr Nardell
You may please share the documents with me too

Roderick Mera Replied at 3:44 AM, 15 Jul 2015

I will like to be sent a copy whenever you are able to sent out the paper. I thank you in advance

Edward Nardell, MD Moderator Replied at 4:06 AM, 15 Jul 2015

Roderick, as I have said a few times, I do not see your email address
through GHDonline, cannot post the article for general use, but will
respond if you send a personal request to . Thanks, Ed

Michael Tladi Replied at 2:10 PM, 20 Jul 2015

Thanks Dr, I email you for the document,
many thanks

Danila Brindak Replied at 12:37 PM, 12 Sep 2015

Dear all
Where can I found more details information from UV sensor traverse method (Rudnick direct method) for measuring total UV output of fixtures? Is this method a more simple and inexpensive in comparison with other (Calibrated Integrating Sphere and Gonioradiometry)?

Dominique Kabengele Kayembe Replied at 1:52 PM, 12 Sep 2015

Also interested in the documents


Elizabete Nunes Replied at 5:51 AM, 14 Sep 2015

Dear Dr Nardell,
If you could kindly make all the three documents available, it would be very important for me because we start to put UVL into central hospital of Maputo in 2013 and this guidelines could help us very much!!.
Thanks and Warm regards,

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