Chairs
Richard Shaughnessy rjstulsau@aol.com
University of Tulsa, USA
Cochairs
Johan Johansson Johan.hp.johansson@sp.se
Swedish National Testing and Research Institute, Sweden
Koichi Ikeda ikedak@iph.go.jp
Insitute of Public Health, Japan
Aim and scope
Develop guidance as to what factors must be considered when evaluating effectiveness of portable air cleaners. The goal is for these basic underlying principles to be integrated into the development of more detailed methods to evaluate these devices in the future.
Status
Workshops conducted at Indoor Air '99 in Edinburgh, at Healthy Buildings 2000 in Helsinki, at Indoor Air 2002 in Monterey, at Indoor Air 2005 in Beijing and at Healthy Buildings 2006 in Lisboa.
Latest Task Force summary from Beijing IA 05 and Portugal Healthy Building 06
Chair: R Shaughnessy, PhD Univ of Tulsa>br>
ISIAQ Task Force Forum: Performance of portable air cleaners
Abstract:
Although air cleaning technology for residences has existed for over 70 years, it has become even more significant of recent, as the general population has become more attuned to indoor air issues. Accordingly, more and more individuals are turning to enhanced air cleaning technologies to improve the air quality in their residences and immediate environments in hopes of alleviating symptoms associated with various diseases such as asthma, rhinitis, sinusitis, and allergic respiratory disease. In a recent report, the business of air cleaning and improved filtration was estimated to encompass sales of over $1.5 billion per year in the US alone.
The primary metric to judge portable air cleaner performance is termed the Clean Air Delivery Rate (CADR). CADR is based on the measured difference in decay or removal rates with the air cleaner in operation and with no air cleaner operation. The units of CADR are flow, i.e., volume per unit time. The resulting metric permits both an intercomparison of performance among various air cleaners and a comparison of air cleaner operation to other contaminant removal processes (such as ventilation and settling).
While CADR is used to describe the performance of an air cleaner with respect to contaminant removal, the benefit of using an air cleaner needs to be assessed in the context of its 'real-world' use. Specifically, the effectiveness of the product at issue should be considered in terms of what is feasible given the current available technology, and should be capable of meeting the industry minimum standard of care of 80% removal of particulate contaminants at steady state. In addition, the impact of indoor chemistry related to the presence of ozone in the indoor environment, and its subsequent effects on source terms within the environment is critical to the overall analysis as to how effective an air cleaner may be in a real-world environment. The goal of the forum is to guide the future work of the ISIAQ Task Force on Portable Air Cleaning Technologies. Previous workshops of the Task Force were held at Indoor Air 99 in Edinborough, and Indoor Air 02 in Monterey CA, Indoor Air 05 in Beijing, and Healthy Buildings 06.
The following represents summary notes from IA 05 session:
ISIAQ task forum on performance of portable air
cleaners
Co-Chairs:
R Shaughnessy, PhD Univ of Tulsa and
R Sextro, PhD, Lawrence Berkeley Lab
Forum Highlights:
Task Force Chair: Richard Shaughnessy, PhD, University of Tulsa, USA
Past meetings of Task force:
Indoor Air 99
HB 2000
Indoor Air 2002
Objective: Provide current information on Portable Air Cleaners to practitioners
and end-users
Agenda for Forum:
Introduction: R Shaughnessy
Short Presentations:
Rich Sextro, PhD, Lawrence Berkeley Labs
What is an Effective Portable Air Cleaner
Jeff Siegel, PhD, University of TX
Efficiency and Efficacy of Portable Ion Generators
Rich Corsi, PhD, University of TX
Portable HEPA Air Cleaner Effectiveness for Shelter-in-Place
Discussion Points:
Effectiveness issue, What is acceptable? (Note: most of this discussion
was focussed on particle removal within the space)
Discussion on this point evolved around questions of what we know
at this time to allow us to set an effectiveness criteria
(effectiveness defined as reduction in steady state particle
concentrations, and thus exposures, within a room afforded by a
portable air cleaner)
Cannot base on health outcomes; health-based criteria are
not currently available (e.g. what should minimum
exposures be)
Effectiveness based on health outcome must also take into
account the agent being removed from the air and its effect
on health
Balance must be attained in air cleaner selection to optimize
parameters such as noise reduction, air flow, energy
consumption, effectiveness, and reduction of human
exposure to specific agents; this optimization must provide
a balance resulting in the practical/feasible limits as to what
reduction in contaminant should be achieved
Group discussion: point raised, that effectiveness of 80% is
reasonable to strive for, given the current technology
available for portable air cleaning devices
. No
disagreement voiced
Concerns raised as to potential for ozone induced oxidation of
semivolatiles, etc that may be attached to particles collected onto
filter media. Further research in this area being conducted as to
contribution to overall pollutant load and end products within the
space
Clean Air Delivery Rate (volume equivalent of cleaned air to an
environment) is a reasonable metric to be used to compare performance
of portable air cleaning devices
Gas Phase Cleaning, Carbon/Photocatalytic oxidation (PCO) usefulness?
More emphasis on this topic should be explored
Concerns raised as to gaseous contaminant fraction and effects on
health
Overall conclusion as to use of PCO in portable air cleaners was
that it may be premature to consider at this time given the modest
reductions that may be afforded by current technologies of PCO
Indoor Chemistry; Rxn Products and Impact on Health
Important topic of concern especially given the number of devices
on the market that either intentionally, or unintentionally,
contribute ozone to the environment
Dissemination of ozone by devices to be avoided in all cases
Primary concern being byproducts of ozone heterogeneous and
homogeneous reactions with indoor compounds resulting in
formation of ultrafine particles and gaseous contaminants (e.g.
aldehydes, ketones, organic acids)
UV-C
Is it useful for PACs?
Direct line-of-sight mechanism
As for usefulnesss on airborne contaminants:
Discussion focussed on specific applications such as direct
use of UV-C in homeless shelters, prisons, health care
facilities to reduce risk of transmission of airborne disease;
application toward reduction of bacteria/viruses may be
useful
Use in general population (offices, homes, schools, etc) may
be premature given the reduced ability to impact fungal
spores
Discussion of residence time and lamp output necessary to
achieve adequate reduction is also of concern if utilized in a
potable air cleaner
Recent developments
forthcoming publications
Brief discussion of forthcoming document by American Lung
Association (ALA) in USA on Residential Air Cleaning Devices;
Covers all aspects of residential air cleaning (both whole house and
portable systems; Should be available on ALAs website in very
near future
Source Control emphasized
Participants stressed the importance of source control being the
primary approach to reducing indoor contaminant load; portable air
cleaners should be considered as supplemental, and never in lieu
of source control measures
Future direction of Task Force
Participation of interested parties welcomed
Formulation of practitioner/consumer-based document may be next
step based on new summary documents that will soon be available
Next Task Force meeting: IA 2008, Copenhagen
Future activities
Next Task Force meeting: IA 2008, Copenhagen
Others
Interested individuals please contact R Shaughnessy (email) to be updated on task force work, and if willing to participate on report.
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