Ultrafine particle removal and generation...

Scientific and technical articles on particle air pollution.

Ultrafine particle removal and generation...

Postby Wilberforce » Mon Jul 07, 2008 12:18 am

Ultrafine particle removal and generation by portable air cleaners
Michael S. Waring, Jeffrey A. Siegel, Richard L. Corsi
http://www.ce.utexas.edu/prof/Siegel/pa ... ner_ae.pdf

Abstract
Portable air cleaners can both remove and generate pollutants indoors. To investigate these phenomena,
we conducted a two-phase investigation in a 14.75m³ stainless steel chamber. In the first phase, particle
size-resolved (12.6–514nm diameter) clean air delivery rates (CADR) and efficiencies were determined,
as were ozone emission rates, for two high-efficiency particle arresting (HEPA) filters, one electrostatic
precipitator with a fan, and two ion generators without fans. The two HEPA air cleaners had count average
CADR (standard deviation) of 188 (30) and 324 (44)m³ h¹; the electrostatic precipitator 284 (62)m³ h¹;
and the two ion generators 41 (11) and 35 (13)m³ h¹. The electrostatic precipitator emitted ozone at a
rate of 3.870.2 mg h¹, and the two ion generators 3.3±0.2 and 4.3±0.2 mgh¹. Ozone initiates reactions
with certain unsaturated organic compounds that produce ultrafine and fine particles, carbonyls, other
oxidized products, and free radicals. During the second phase, five different ion generators were operated
separately in the presence of a plug-in liquid or solid air freshener, representing a strong terpene source.
For air exchange rates of between 0.49 and 0.96 h¹, three ion generators acted as steady-state net particle
generators in the entire measured range of 4.61–157 nm, and two generated particles in the range of
approximately 10 to 39–55 nm. Terpene and aldehyde concentrations were also sampled for one ion generator,
and concentrations of terpenes decreased and formaldehyde increased. Given these results, the pollutant
removal benefits of ozone-generating air cleaners may be outweighed by the generation of indoor pollution.
© 2008 Elsevier Ltd. All rights reserved.
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