TB Infection Control

There are certain guidelines on placement of UVGI fixtures in occupied spaces. Feel free to call me at 212.604.8034 and I will be glad to discuss this with you.

Regards,
Richard Vincent
St. Vincent's Hospital NYC
212.604.8034

This is not a short answer. You can discuss with Mr. Richard Vincent as suggested. Let me lay out some of the issues here, briefly, and refer you to references that are
on line here - especially the 2-part guidelines to upper room UV (fist author, Melvin First, PE, ScD.)
1. How helpful - depends on the setting, ceiling heights, air mixing in the waiting room, etc, but generally the experimental studies published indicate that you can add approximately 10 or more "equivalent" room air changes to whatever real air changes you have. That is a lot of air disinfection and for very little cost, especially in Fla where you would not want to exhaust an additional 10 ACH of cooled and conditionded air outside for energy reasons.
2. Installing UV is relatively easy, once the appropriate fixtures have been identified and someone with some experience decides where they should go - ie, on the walls, suspended from the cieling, etc. The goal is to flood the space well above occupants heads with high intensity UV while keeping levels in the occupied space low enough not to cause eye irritation. This is usually not difficult.

Generally speaking we have been using approximately one ...

This is not a short answer. You can discuss with Mr. Richard Vincent as suggested. Let me lay out some of the issues here, briefly, and refer you to references that are
on line here - especially the 2-part guidelines to upper room UV (fist author, Melvin First, PE, ScD.)
1. How helpful - depends on the setting, ceiling heights, air mixing in the waiting room, etc, but generally the experimental studies published indicate that you can add approximately 10 or more "equivalent" room air changes to whatever real air changes you have. That is a lot of air disinfection and for very little cost, especially in Fla where you would not want to exhaust an additional 10 ACH of cooled and conditionded air outside for energy reasons.
2. Installing UV is relatively easy, once the appropriate fixtures have been identified and someone with some experience decides where they should go - ie, on the walls, suspended from the cieling, etc. The goal is to flood the space well above occupants heads with high intensity UV while keeping levels in the occupied space low enough not to cause eye irritation. This is usually not difficult.

Generally speaking we have been using approximately one 30 W (nominal) wall fixture for each 200ft2 floor area. Ideally it is placed at least 7" off the ground, allowing at least another additional ft of ceiling height for air disinfection. If possible, we place fixtures on the short wall of rectagnular rooms, thereby allowing maximum ray length since the benefit of the UV ray ends when it strikes the wall. However, safety and other considerations, like wall availability, often require other placement decsions. Multiple fixtures in large spaces interact with each other and the goal is to produce as uniform coverage of the upper room as possible.

Fixtures. There are no "standard" UV fixtures. We have found several manufacturers that produce reliable equipment that is well designed and performs well in terms of UV output. Mr. Vincent can give you additional details on specific equipment.

Meter and consultants. It is a good idea to either purchase a UV meter to check the details of an instalation using guidelines we can supply, or hire a consultant who can do this and has a meter. There are very few qualified consultants, unfortunately.

Rumors about high maintenance requirements for UV are greatly overstated, especially by comparison to mechanical HVAC systems. Under most clean clnical conditions, simply changing the lamp once a years is all that is required. However, in new installations, it is good to whipe the lamps down (turned off first) with alcohol every 3 months with pre and post cleaning measurements with a sensitive UV-C meter to see if cleaning made any difference in output. We can provide more specific instructions on how to do this.

Safety is also raised as a limitation, but you should also find citations on this site of recent publicaations by me and others here at Harvard showing that upper room UV is extremely safe. The only complications tend to be due to human error - leaving a fixture turned on when it is cleaned, or when someone is working in the upper room. Appropriate policiesl, training, and signage should avoid most such incidents.

That is a brief overview. Using upper room UV is not rocket science, but some thought and, ideally, experience is useful in avoiding mistakes. Mr. Vincent has offered his advice by phone and I would take advantage of it.

Ed Nardell, MD