Conversion
(Photo Catalytic
Oxidation)
Technology
Why Now?
ASHRAE’s Position
On June 24, 2009, ASHRAE’s Board of Directors approved a position document on Airborne
Infectious Diseases.(18) The document was written by a committee of engineering and health
professionals from around the world. The committee examined available information on the health
effects of exposure to airborne infectious diseases and the implications of this information on the
design, installation, and operation of HVAC systems.
CLCH-PRB023-EN 9
Introduction
The paper discusses three methods of disease transmission: Direct contact, large droplet contact,
and droplet nuclei inhalation. It acknowledges that the HVAC professional is likely to have direct
influence only on the transmission of droplet nuclei.
As contact transmission control procedures, such as hand sanitizers and masks, become more
commonly used, the transmission of airborne droplet nuclei by natural air currents and HVAC
systems will receive more attention as an important pathway of airborne infectious disease.
ASHRAE’s position is that:
• • Many infectious diseases are transmitted through inhalation of droplet nuclei.
• • Droplet nuclei can be disseminated through building ventilation systems.
• • Airborne infectious disease transmission can be reduced by using dilution ventilation, inroom
flow regimens, room pressure differentials, personalized and source capture ventilation
and air cleaning.
ASHRAE recommends that further research be conducted on the development of more
engineering control strategies to reduce infectious disease transmission. In the meantime, it seems
practical for design professionals to understand and consider the control measures available
today, including dilution ventilation, space pressure differential, and air cleaning.
Conclusions
A common finding of recent research is that a significant amount of infectious particles are less
than 4 mm in size. Particles of this size can remain suspended in indoor air for long periods of time
and be recirculated throughout the building by natural air currents and the HVAC system (see
Table 1, p. 7). This validates an airborne disease transmission path that is not being adequately
addressed by the surface and close-contact precautions being used today.
Based on research findings and on ASHRAE’s position, it seems prudent for infection-control
professionals and building designers to consider additional control measures for airborne
transmission, in addition to the precautions already in use when designing new healthcare facilities
and updating existing facilities.
Uses:
To convert Volatile Organic Compounds
To reduce airborne biological contaminates
Conversion
Redox reaction: A reaction in which electrons are transferred
from a donor (the reducing agent) to an acceptor molecule
(the oxidizing agent)
Photocatalysis Process
What is Photocatalysis?
The Oxidation of Carbon using
Hydroxyl Radicals



Filtration has been in common use for many years – PCO is not filtration (Capture). PCO
does not capture
Photolysis is understood and used in multiple applications throughout the world –
PCO is not Photolysis (Cleaning surfaces) PCO does not clean surfaces - (the UVC lamps used
for energy will clean exposed surfaces)
Photocatalysis (PCO) using a semi-conductor such as titanium dioxide (TiO²) has been
known and pursued for at least twenty-five years but it has application and production
constraints
PCO produces Hydroxyl Radicals
Photo Catalytic Oxidation is a Conversion Process
Conversion = Reduction of Organic Contaminants (lower energy cost) vs Dilution by introducing ODA
(issues: equipment sizing, energy costs and pollutant introduction)
Challenges with capture alone:
•
•
•
•
Pressure
Space
Energy Cost
Sustainability
What is Conversion?
The Oxidation
of Carbon
• The Oxidation of Carbon
• The Reduction of Volatile Organic Compounds
• Destruction of Cellular Structure of
Pollen, Mold, Bacteria and Virus
• Production of H20 and CO2
Note: PCO is not a scavenger technology
The oxidizing agent is not broadcast into the space.
What is that thing that looks like a
filter with a light in it?
Think of my car’s
Catalytic Converter
Mechanical
Reduction
Device
This is a Filter with Light?
Are all PCO products the same?
Advantages:
Low Static
Pressure Drop
Smaller AHU
Life Cycle
Destruction or
Conversion
Difference:
Dwell Time
Energy
Distribution
Self- Renewing
Caution:
Does the
product produce
harmful
intermediaries?
PCO completes the IAQ Puzzle
Testing to be sure
RTI AO3230902 – LBNL58936 Results
In conclusion, the Office Mixture was introduced into the Populated Catalyst
Panel Air Cleaner at three air flow rates. Sampling for aldehydes and volatile
organics showed no statistically significant production of aldehydes or VOCs at
the α = 0.05 level except for a small increase in acetone at one flowrate.
•RTI International R Keith Esch, Ph.D Microbiologist
•G.D. Air Testing, George Dai, Ph.D
•HRA Environmental, Dr. Hamid Arabzadeh, MS, CIH, CSP, REA, CHMM
•U.S. Army Developmental Test Command - Dugway Proving Ground
Douglas A. Tamilio LTC, IN Commander, West Desert Test Center
•Prism Analytical Technologies Randall S Fike, Ph.D
•Quality Environmental Services Joe Boatman, Ph.D
•Eastmount Environmental Services LLC Thomas G. Hopper, PE
•RTI International Kathleen Owen, Chemical Engineer
Bacillus atrophaeus Anthracis, Staph, E. Coli,
-Aspergillus, MS2 Virus, - TB,Cladosporium
-VOCs
- Mold in a VA Hospital
-Aspergillus Niger, MS2 Virus,
Bacillus Subtilus stimulate for (Anthrax)
-VOCs University of Cincinnati
- Environmental Tobacco Smoke
- MEK/Methanol Reduction Thermal Oxidizer
- Checking for production of by-products
Types of testing:
Recognized third party
National Labs / Published Papers
Protocol:
Device on and off – establish baseline
With and Without pre-filter
Recirculated and Single pass (500fpm.)
Agents:
Those that will not commit suicide in an
air- stream
Case Studies / Published Reports
Concentration Reduction
By Conversion (500fpm.)
IMPORTANT NOTE: Even without filtration,
PCO shows a reduction in microbial contaminants!
Mechanical Dilution by Conversion
MERV 13 Filter
Dugway Test
Catalyst
Removal Rate, Remainder, Results of Genesis Destruction Rate of
Possible
%
%
Catalyst
Remainder, %
Infiltration, %
Mold
80
20
94.7
18.94
1.06
Bacteria
80
20
98
19.6
0.40
Virus
50
50
98
49
1.00
“As designed and tested the
PCO system was able to
remove or neutralize better than
98% of the airborne material as
it processed the test chamber.”
Dugway Proving Grounds Western Desert Test Center
(2006). WDTC-TR-06-078,3.8,33.
Dugway and Bio-graphs
Will PCO Work ?
Organic - Yes
Inorganic - No
Best use:
Reduction of VOC’s
Reduction of Airborne
Biohazards