NC Bronx Hospital

UVGI upgrades Airborne Disease Control

North Central Bronx Hospital uses UVGI units to reduce TB transmission rates. By destroying airborne pathogens, UVGI minimizes the spread of infectious particles from the bronchoscopy operating room. Because the UVGI units are cost-effective to purchase and maintain, they add a level of protection in the bronchoscopy room and other areas where alternative control technologies would be difficult or prohibitively expensive.

The Challenge	In the early 1990s, tuberculosis (TB) cases were increasing throughout New York City and other large US cities, placing hospitals' staffs and patients at increased risk.
The Traditional Approaches	Most environmental controls for airborne pathogens rely on regulating air movement and filtering the air, such as increasing ventilation, negative pressure isolation rooms and HEPA filters.
The UVGI Solution	North Central Bronx Hospital turned to Ultraviolet Germicidal Irradiation (UVGI), installing two wall-mount units at a height of seven feet six inches.
The Results	UVGI adds valuable supplemental protection against TB and other infectious diseases for employees and patients and offers many additional benefits.
What did it all cost?	Capital costs of the UVGI units at North Central Bronx Hospital ranged from $550 to $1600 per unit. Installation cost, including labor and materials, was $350 per unit.

The Challenge: Protecting Patients and Staff from TB Infection

In the early 1990s, tuberculosis (TB) cases were increasing throughout New York City and other large US cities, placing hospitals' staffs and patients at increased risk. North Central Bronx Hospital looked for ways to further protect its employees and patients against TB infection.

The hospital first improved staff education, screening, and signage in its emergency room. For example, patients who cough are quickly identified and sent directly to the triage desk, where nurses immediately see and isolate them.

The hospital turned to engineering and environmental controls to further ensure the safety of patients and staff. But one hospital area, a bronchoscopy room located within a suite of operating rooms, presented a unique challenge. Because traditional methods failed to provide the desired level of protection, the hospital implemented the then developing UVGI technology to reduce the risk of TB infections.

The Traditional Approaches

Tuberculosis (TB), measles, influenza, and other airborne infectious diseases are generally transmitted through small "droplet nuclei" that are expelled into the air by infected persons when they cough, sneeze, or speak. As air currents in the room circulate these droplet nuclei, employees, patients, and others can inhale them. The person can then contract the disease from inhaled droplet nuclei that lodge in the lungs or respiratory tract.

Most environmental controls for airborne pathogens rely on regulating air movement and filtering the air. Environmental controls used at North Central Bronx Hospital include:

Increased ventilation. In places where airflow could be adequately controlled, North Central Bronx Hospital increased ventilation rates to dilute or remove potentially contaminated air.
Negative pressure isolation rooms. The hospital created negative pressure isolation rooms by installing exhaust fans in some of the same areas where ventilation was increased. The fans remove contaminated air and create a pressure differential that reduces airflow from isolation rooms to adjacent rooms.
High efficiency particulate air (HEPA) filtration. The hospital installed HEPA air filters in air ducts in many locations where airflow control was not feasible or cost-effective.

Although these methods were used in many locations, they did not provide the desired level of protection and were unsuitable for the bronchoscopy room. Lung biopsies performed there require a bronchoscope, which is a long slender tune inserted in to the lungs that causes patients to cough frequently, expelling droplet nuclei. The positive-pressure environment required for operating rooms by New York State law actually increased the likelihood that infected droplet nuclei would leave the room and contaminate adjoining rooms.

One possibility was to establish negative pressure in the bronchoscopy room and separate it from the rest of the operating suite, but this was prohibitively expensive.

The UVGI Solution

To cost-effectively deal with infectious particles in the bronchoscopy room, North Central Bronx Hospital turned to Ultraviolet Germicidal Irradiation (UVGI), installing two wall-mount units at a height of seven feet six inches. Each unit contains a fan, a washable electrostatic filter that can remove airborne particles as small as 5 microns, and one or more 25-watt UV lamps.

The special low-pressure mercury lamps in the units produce UV-C radiation with a 253.7 nanometer (nm) wavelength. When a microorganism in an airborne droplet nuclei passes through this irradiation, its DNA is penetrated and destroyed, disabling the microorganism's ability to replicate and transmit disease. Experts estimate that UVGI destroys up to 99% of the rooms airborne pathogens, given sufficient air mixing and resident time.

The bronchoscopy room installation and eight additional UVGI room air sanitizers in the ER waiting room have offered increased protection for the hospital's patients and staff since 1995.

The Results: Increased TB Protection

UVGI adds valuable supplemental protection against TB and other infectious diseases for employees and patients and offers many additional benefits.

Reduction in TB conversions. While the hospital treated 55 new TB cases in 1992, it treated only 22 in 1995. Staff conversions dropped from almost 3% in 1992 to a single case in 1995, an annual rate under 1%.
No hospital-acquired TB infections. Since implementing the new infection control measures, no TB infection transmissions within the hospital have been documented.
Easy maintenance. Units require just minor quarterly cleaning. The procedure involves only vacuuming and washing the filters and wiping the lamps with water or alcohol.
Minimal maintenance costs. The 10,000 hour UV lamps are replaced annually at a cost of $40 to $50 per lamp.
Safe operation. The UV-C lamps are totally enclosed to reduce any possibility of tissue irritation that might be caused by direct exposure. Units are mounted at 7- to 8-foot heights to reduce exposure at eye level.
Low operating costs. Yearly operating cost for a UVGI unit averages about $35.

What did it all cost?

Capital costs of the UVGI units at North Central Bronx Hospital ranged from $550 to $1600 per unit. Installation cost, including labor and materials, was $350 per unit.