Air Date: 10-10-2014| Episode: 343
This week on IAQ Radio we welcome back Richard Corsi, PhD and University of Texas at Austin PhD Candidate Brandon Boor for a discussion about bringing research to practitioners…
This week on IAQ Radio we welcome back Richard Corsi, PhD and University of Texas at Austin PhD Candidate Brandon Boor for a discussion about bringing research to practitioners. We will focus on some of Mr. Boor’s research projects and discuss how they can assist IAQ practitioners in the real world. Dr. Corsi is the Chair & ECH Bantel Professor for Professional Practice Civil, Architectural & Environmental Engineering at The University of Texas at Austin. He earned his Ph.D. in civil engineering from the University of California at Davis in 1989. He joined the faculty of The University of Texas at Austin in 1994. Dr. Corsi researches indoor air quality, including sources and control of indoor air pollution and human exposure to indoor toxins. He has also studied how architectural materials can remove chemicals from building air, offering protection for occupants following terrorist attacks.
We are also looking forward to an update on the IAQA/ASHRAE unification with Eva King, PhD. This will also be the first in a monthly series of interviews with IAQA updating listeners on how things are going with the two groups now working together.
Research to Practice
(With IAQA/ASHRAE Merger Update)
This week’s guests on IAQradio were Dr. Richard Corsi, PhD the Chair & ECH Bantel Professor for Professional Practice Civil, Architectural & Environmental Engineering at the University of Texas at Austin and Brandon Boor one of Dr. Corsi’s graduate students.
Nuggets mined from today’s show:
Tell us a little about the number of research projects your students have been and are doing?
- 4 faculty members (soon to be 5) research IAQ while supervising grad students and undergrads. The research is focused on understanding source characterization and pollutant transport within buildings and human exposure to pollution. A wide range of contaminates is studied from meth lab contamination to wildfires. Areas of interest include: the importance of airflow patterns around human body, how we inhale with a concentration on infants and children, remedial strategies such as air filter/cleaners and how building energy use effects IAQ.
- Depending on research funding the number of concurrent projects varies between 6- 15. Research projects funded by industry tend to be shorter duration (3 months) while government funded projects may take 2-4 years. As grad students often take 20 months to complete their program, it’s preferred when the duration of a study coincides with the amount of time the student needs to complete their program.
- The National Science Foundation (NSF) is open to funding a wide range of projects. Obtaining funding from the NSF is long shot with only a 5% chance of getting funding on self chosen project. EPA and ASHRAE are more focused on what they are looking for. Some students get their own funding.
As a student in Dr. Corsi’s exposure course, the combination of exposure to flame retardant from mattress and curiosity about exposure during sleep piqued his interest in studying exposure during sleep.
- While many studies (around 100) have been done characterizing mattress dust and allergens and microorganisms in mattress dust, a research gap exists on human exposure during sleep. His research focused on: how particles become airborne, exposure and pollutant transport dynamics, characterization of additional contaminates, role of humans and bedding on particle resuspension, etc.
- Crib mattresses can contain flame retardants and other chemical additives.
- Prevent buildup by routine weekly or biweekly vacuuming and frequent laundering of bed linen and pillow covers. Comforters (or top surface blankets on a bed) may accumulate particles generated elsewhere in the house, or originating outdoors.
Brandon’s sleep studies:
- To minimize background contamination the study was conducted in a controlled environmental chamber. Twin size mattresses were wrapped in two layers of bed sheets. The study used an artificial contaminate (test dust) to measure mattress dust re-suspension. Study participants modeled sleep activities. Study subjects wore protective clothing to minimize addition of contaminates. Study subjects performed 5 different movements of varying intensity during which particle release was measured with optical particle counters. Study segments were divided into 12.5 minute duration events.
- Ventilation in the chamber was provided by a diffuser mounted near the floor. Ventilation air was pre-cleaned with a HEPA filter. Air changes were varied between 1-7 times per hour. While ventilation reduces exposure, ventilation doesn’t impact re-suspension. Finding: The intake fraction of inhaled pollutant was an order of magnitude higher at lower air exchange (1 per hour) rather than at higher (7 per hour)
- Test dust was comprised of particles ranging between 1-20 microns. 1-10 micron particles represent various mite and animal allergens, fungal spores, and bacteria. 10-20 microns particles detach and are more easily re-suspended than smaller particles of 1-2 microns.
- Common sleep movements release particles. Complex airflow regimes are generated by movement during sleep. Particles readily pass through porous bed sheets. Direct contact, abrasion, vibrational forces re-suspend particles. Larger particles are like bowling balls and release more readily and settle more readily. Exposure to smaller particles (around 1 micron) is longer (low settling velocities) prolonging exposure.
- Further study was conducted on arrangement of with pillows and various weight blankets. Findings: blankets accumulate particles from other places in home. Deposited particles on pillow pass through the pillow cover, no barrier to particle transport.
- What can Indoor environmental contractors or consultants learn from this study that would help them do a better job evaluating, advising or cleaning bedding, etc? Get rid of the dust, clean and vacuum, re-suspension from indoor surfaces will always occur to some extent unless they are completely free of deposited particles, keep pets out of bed, use personal air cleaners and good ventilation. Dr. Corsi adds- In addition to bacteria and shed skin flakes mattresses incorporate flame retardants and other chemicals which can become airborne in gas phase and latch onto other particles. Some of these chemicals are endocrine disruptors. More than a biological risk, there is also a chemical hazard.
- VOCs and other chemicals are emitted from crib mattresses. Our study (conducted in Finland) tested new and used crib mattresses and while finding that new mattresses emit more than older mattresses also found used mattresses up to 10 years old also emitted VOCs. Prior to using a new crib mattress: remove plastic wrapping and allow new crib mattresses to air out. Temp effects off gassing, body heat and heating blankets raise temp and increases emissions. VOC exposure in cribs is double what is in balance of the room (bulk air).
Eva King, PhD IAQA/ASHRAE update:
- A transition team of volunteers from both orgs along with management staff chat weekly. Continue painting another piece of the big picture. Both boards of directors have met face-to-face. IAQA management has moved to Atlanta. Introducing chapters is being strongly encouraged. IAQA board members are making presentations on the merger. Encouraging collaboration. Opening many new opportunities.
- Queried Brandon about his familiarity with Australian research paper on daytime dust mite exposure. In fact, Brandon had organized a well received panel in Hong Kong on which the author of the Aussie paper participated.
- “Hygiene hypothesis” is directed to microbial exposure not dust mites.
Dr. Corsi on air purifiers:
- Has researched both whole room air purifiers and a commercial unit designed for nightstand. Using thermal mannequins which breathe, the nightstand unit was found to reduce suspended particles in the breathing zone 90%. The nightstand unit cleanses the air and blows clean air over face while sleeping. Personal air cleaners don’t make excessive noise. Having air blown over face while sleeping is a matter of personal choice.
- Dr. Corsi- Using thermal breathing mannequins and collect air samples from lungs has shown that pulling blanket over head increases gas exposure 20-30 times and will inhale 60% of own breathe not breathing fresh air. Parents can reduce children’s exposure by preventing kids from pulling covers over heads while sleeping.
- Dr King final comment- encourages ASHRAE/IAQA members to provide feedback be active in chapters and participate in association events.
- Brandon Boor- Thermal comfort aspect – study bulk air and airflow around the body. Buoyancy of warm air transports particles into breathing zone, but may also dilute concentrations in breathing zone by entraining “fresh” air exterior to sleep microenvironment
Today’s music: University of Texas Longhorns Fight Song
Z-Man signing off