Since 1989, HealthChem, Inc. has been providing quality contract project services for high-tech industry nationwide.
Airborne Disease Control Systems

A work hazard presently facing health-care workers and their patients is the potential transmission of tuberculosis, particularly multi-drug resistant forms (MDR-TB). HealthChem evaluates, designs and installs air-borne disease control systems based on criteria recommended by Centers for Disease Control (CDC) Guidelines for Preventing the Transmission of Tuberculosis in Health-Care Facilities

Engineering controls to reduce routes for disease transmission include fresh-air dilution, pathogen removal by ultra-high efficiency particulate air filtration, and disinfection by UV irradiation. Potentially contaminated rooms must incorporate pressure and ventilation controls to maintain:

* Fresh-air ventilation and mixing to dilute and remove air-borne droplet nuclei

* Control of air flow through the room

* Negative relative pressure for air inflow

* Air exhaust to outdoors away from intakes

Maintaining negative pressure relative to the adjacent corridor assures that potentially contaminated air does not enter the hospital's common areas. Sufficient fresh air ventilation to dilute the level of airborne bacilli is about 15 cfm/occupant, but the use of outdoor dilution air requires additional heating and air conditioning for room climate control.

The safest facility air flow should be determined by our ventilation engineer. Air exhaust systems connected to common headers must be sealed, and negative duct pressure maintained.

Bronchoscopy, aerosolized pentamidine treatments, endotracheal suctioning or diagnostic sputum induction must be performed in a dedicated isolation room or booth which includes increased dilution air, negative relative pressure, filtration of recirculated air and exhaust control.


Infectious Bacilli Removal by High Efficiency Particulate Air (HEPA) Filtration

Tuberculosis and fungal respiratory diseases are transmitted by airborne infectious particles carried at low ambient concentrations. HEPA filters have been shown to be effective in clearing the air of Aspergillus spores, which are about the same size as M. tuberculosis bacilli

HealthChem client facilities are protected by large multi-zonal HEPA filtration systems continuously removing up to 99.97% of airborne pathogens larger than 0.3 m m. Locating dedicated wall or ceiling-mounted HEPA filter modules and return air registers using smoke tests and air flow models is a cost-effective way to reduce the spread of infectious particles throughout the room.

CDC states that "portable HEPA filtration units have not been evaluated adequately to determine their role in TB infection control programs". The portable unit's effectiveness is dependent on all of the room's air passing through the filter element, so they are only useful for short-term intervention.

An engineered HEPA filtration system optimizes:

* Required air recirculation rate

* Particle removal efficiency

* Air flow pattern

* Relative negative pressure

* Maintenance and monitoring requirements

The air filtration system includes easily-replaceable pre-filters to remove relatively large room dust particles, and passes the supply air through the ultra-high efficiency filter modules to remove remaining droplet nuclei smaller than 5 m m. It is also safer to HEPA filter or UV disinfect the air prior to exhaust to the outdoor environment

Germicidal UV Irradiation

Irradiation by ultra-violet (UV) light has proven to effectively kill pathogens, and M. tuberculosis is particularly susceptible. UV light in the 254 to 260 nm range is powerfully germicidal. When air from rooms of patients with infectious tuberculosis was passed through an intensely irradiated duct at a low velocity, no exposed test guinea pigs were infected.

CDC recommends UV lamps (with appropriate safeguards to prevent short-term overexposure) as a supplement to ventilation. Effective and safe UV germicidal irradiation (UV-C) design ensures pathogen disinfection while maintaining patient exposure below the NIOSH 24-hour limit of 0.1 m W/cm2. Key irradiation design factors include:

* Lamp placement

* Radiation dosage rate

* Control of dosage time

* Access for checking and cleaning bulbs

UV-C is most effective against droplet-borne organisms, or tiny droplet-nuclei which are most likely to penetrate and be retained in deep pulmonary spaces. Larger pathogen-carrying dust particles fall to the floor or are removed by HEPA filters.

Iso-alert Monitoring Panel

Each pathogen controlled area is provided with a custom Iso-alert Monitoring Panel which supervises and annunciates ventilation, disinfection and climate conditions locally or at a remote location such as a nurse's station via standard control wire. Each isolation area is continuously monitored for:

* Relative negative room pressure

* Exhaust operation

* HEPA filter operation

* Disinfection lamp operation

Isolation Room Design and Validation Services

After we've designed isolation systems to meet your facility requirement, HealthChem will assist you in obtaining any building or work permit. After approval, equipment is installed in a clean, safe and professional manner.

HealthChem will validate the completed TB control system to assure that the design requirements are satisfied. We can provide a service contract which includes system maintenance and periodic system testing and certification as required by OSHA


Reference Projects

Newark Community Health Centers, Newark, New Jersey

To reduce chances of tuberculosis infection in two primary-care clinics, we designed multi-zonal disease transmission control systems. Each zone has a dedicated recirculation fan with supply and return duct-work to pre-filters and multiple HEPA filtration modules. UV-C disinfection lamps are applied in waiting rooms and controlled zones are monitored via an Iso-alert panel.

Community Hospital of Brooklyn, Brooklyn, NY

Designed TB transmission control systems for three areas of possible transmission; Emergency Treatment Room, Patient Waiting Room and Ward Isolation Rooms. The state-of-the-art design includes conditioned fresh air supply, HEPA filtration, UV-C disinfection and dedicated room exhaust. Iso-alert monitoring panels assure regulatory compliance.

Community Hospital of Brooklyn, Brooklyn, NY

Designed and installed a ventilation system for the Nuclear Medicine Test Room and Nuclear Chemicals Storage Room. In compliance with the N.Y.C. Department of Health Code, the ventilation system allows use of an advanced Picker machine which utilizes an aerosol DTPA radioactive tracer.

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