LEED certification may not guarantee good IAQ

A report indicates that buildings with U.S. Green Building Council LEED-certifications remain susceptible to spikes in fine, airborne particulates, and low IAQ. The preliminary findings were presented at the American Academy of Allergy, Asthma, and Immunology annual meeting. The report suggests that LEED certification remains an imperfect way to determine IAQ.

Since indoor air pollution is not currently regulated in the United States, except under workplace standards, the LEED program developed its own standards for IAQ. For fine particulates—particles 10 microns or less (PM10)—the limit is a four-hour average of 50 micrograms per cubic meter (mcg/m3). The current U.S. Environmental Protection Agency standard for outdoor particulate pollution is a 24-hour average of 150 mcg/m3.

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The results changed when the investigators ran a vacuum cleaner for a few minutes to simulate the effects of human activity. The PM10 readings spiked to as high as 60 mcg/m3and even larger surges were seen when indoor sampling coincided with nearby construction activity. The indoor PM10 readings rose to 200 mcg/m3for a period of 15 minutes, and then dropped to less than 30 mcg/m3at the end of the workday. The researchers went on to study occupied schools, apartments, and offices. The team found that the PM10 levels increased well beyond the LEED limit when people were inside doing normal activities.

The researchers did find that buildings failing to receive LEED certification tested much higher for PM10s; which demonstrates how the LEED program does help reduce indoor air pollution. A limitation of the study was that it did not address levels of PM2.5 (particles smaller than 2.5 microns). The LEED standards do not set limits for these ultrafine particles, although they are considered more dangerous than larger particles.

“Greenbuildings: LEED Certification Requirements for Indoor Airborne Particles Can Reduce Indoor PM10 Exposure”
E. Horner, P. Fritz, M. Califano, N. Sanders
The Journal of Allergy and Clinical Immunology

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