CARB Research Seminar

This page updated March 6, 2018

Characterizing Formaldehyde Emissions from Home Central Heating and Air Conditioning Filters

Photo of Hugo Destaillats, Ph.D

Hugo Destaillats, Ph.D., Lawrence Berkeley National Laboratory

April 03, 2018
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA

Research Project


Formaldehyde is a carcinogen and a strong irritant. Many indoor sources of formaldehyde can be found in residences. Among those sources, fiberglass particle filters produce formaldehyde upon decomposition of polymeric additives. The goal of this study was to assess formaldehyde emissions from residential fiberglass filters relative to synthetic filters, and estimate their contributions to indoor concentrations in California homes.  

In laboratory bench-scale and room-sized environmental chambers, emission rates were determined for several filters at moderate (33 - 40 %) and elevated (62 - 72 %) relative humidity, and two different flow rates (680 and 1700 m3 h-1).  The results showed that fiberglass filters emitted more formaldehyde than synthetic filters.  At high RH, emission rates from the same filters increased to 500 - 3500 µg h-1 m-2, but from synthetic filters were only 100 - 120 µg h-1 m-2. The core filtration media and the glued frame each contributed about half of the formaldehyde emissions.  Formaldehdye emissions from fiberglass filters increased significantly with RH and face velocity.  Great variability in emissions was observed among fiberglass filters from different manufacturers. The length of storage appeared to be the primary factor reducing emissions over time.

Contributions to indoor formaldehyde concentrations were predicted for homes of different sizes, with different air exchange rates, using different filter sizes, and in different climate zones. Under most conditions, contributions of fiberglass filters to indoor formaldehyde levels were estimated to be small.  However, under certain conditions (e.g., a very small apartment with low air exchange), fiberglass filters were estimated to increase indoor formaldehyde by 2.5-9.3 ppb, sometimes exceeding the California chronic reference exposure level and Proposition 65 no significant risk levels.  This study demonstrated that residential fiberglass filters emit formaldehyde in contact with humidified air, consistent with previous studies of filters used in commercial buildings. This study also showed that the use of synthetic particle filters instead of fiberglass filters could be a part of the solution to reduce indoor formaldehyde exposures.

Speaker Biography

Hugo Destaillats, Ph.D., is a Staff Scientist and Deputy Leader of the Indoor Environment Group at the Lawrence Berkeley National Laboratory. Prior to joining LBNL in 2003, he was a postdoctoral researcher at the California Institute of Technology (1998-2001) and at the University of California, Davis (2001-2003). Dr. Destaillats' research over the past 20 years has been in the fields of environmental, physical and analytical chemistry. Current efforts are aimed at understanding the sources, transport and elimination of indoor trace pollutants, preventing or mitigating human exposures to harmful chemicals, and developing new technologies and materials for healthy and energy-efficient built environments. Dr. Destaillats has published more than 60 articles in peer-reviewed journals, and holds a Ph.D. in Chemistry from the University of Buenos Aires, Argentina.

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