BY TODD CRAWFORD, PATRICIA FRITZ, MEMBER ASHRAE; THOMAS WAINMAN
This article was published in ASH RAE Journal, December 2018 . Copyright 2018 ASH RAE. Posted at www .ashrae.org . This article may not
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Todd Crawford, Patricia Fritz, and Thoman Wainman are research scientists at New York State Department of Health in Albany, NY.
ASHRAE Standard 62.1 has long established that an occupied space requires an adequate supply of clean air to maintain acceptable indoor air quality (IAQ). The most common source of clean air-outside air-must be conditioned at a price; fans, filters, heating, cooling, and tempering are major capital, maintenance and operating expenses in buildings. Consequently, ventilation systems are designed to preserve as much of the conditioned air as possible by cleaning and recirculation . ASHRAE’s IAQ Procedure 1 describes a method to reduce the proportion of outside air supply by treating
(cleaning) and recirculating air. ASHRAE’s IAQProcedure is akin to the Exception in International Mechanical Code §403.2 (2010):
“Where the registered design professional demonstrates that an engineered ventilation system design will prevent the maximum concentration of contaminants from exceeding that obtainable by the rate of outdoor air ventilation … the minimum required rate of outdoor air shall be reduced in accordance with such engineered system design.”
Corona discharge (sometimes labeled: ionizing, negative ion, bipolar ionizing, activated oxygen, mountain fresh air, etc .) often is a proposed air cleaning technology to remove airborne contaminants. Corona discharge ionizes oxygen in air and generates an electrostatic field. The design of the corona discharge system can be modified to create mixtures of reactive oxygen species (ROS): ozone, hydroxyl radicals, and superoxide anions .2 Ozone emissions from air cleaners are regulated in California 3 and are generally discouraged in many states’ guidance documents.