AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Application of ISO 14644 as an Indoor Air Quality (IAQ) Metric
ELLIOTT HORNER, Nate Sanders, UL Environment
Abstract Number: 607 Working Group: Indoor Aerosols
Abstract ISO standard 14644-1 establishes count concentration limits of airborne particulate matter (PM) to characterize environments by levels of air cleanliness. The PM limits for each cleanliness class vary according to PM size. Classes 1 (lowest limits) through 9 (highest PM concentrations) are defined in the standard. Although ISO 14644 is primarily used for controlled environments such as clean room manufacturing or research facilities, classes 8 and 9 overlap with clean, well-maintained indoor spaces. PM measures are increasingly focused on smaller size PM, at and below 1 µm. Mass concentration becomes less useful in this size range and requires impractically high sample volumes for indoor spaces.
We applied the high end of the ISO 14644 range to characterize indoor spaces. Count concentration data were collected with an optical particle counter while monitoring renovation activities adjacent to occupied healthcare spaces. PM readings from 185 observations (5 locations, 37 occurrences) were assessed for conformance to ISO 14644 criteria for 0.5 micrometer and for 5 micrometer particle sizes. For 0.5 micrometer size PM, 43% of observations were Class 9 and 57% were Class 8. For 5 micrometer size PM 30% of observations were Class 9, 64% were Class 8 and 6% were cleaner than Class 8.
These empirical findings classified the spaces within the highest three Classes (of nine) outlined in ISO 14644. These were not controlled environments, but were clean, well-maintained buildings with high ACH and good quality filtration. This demonstrates that ISO 14644 Class ratings can be used as an IAQ metric to characterize the PM burden on a count concentration basis in occupied buildings. The optimal particle size for characterization should be considered and a three tier system (not rated, rated as Class 9, cleaner than Class 9) may be the limit of utility however.