Air Date: 9-22-2017|Episode 478
This week we welcome two up and coming researchers and academics to discuss a topic that has recently been getting some much deserved attention. Most people spend about 1/3 of their lives in bed and or sleeping. What are we breathing or absorbing and how does it affect our health and performance? Dr. Boor and Dr. Laverge will tell us what they have learned during their literature review on the topic.
This week we welcome two up and coming researchers and academics to discuss a topic that has recently been getting some much deserved attention. Most people spend about 1/3 of their lives in bed and or sleeping. What are we breathing or absorbing and how does it affect our health and performance? Dr. Boor and Dr. Laverge will tell us what they have learned during their literature review on the topic. We also look forward to learning what these up and coming academics feel are other important IAQ questions and answers we will be discussing over the next decade. Dr. Boor joined us once before with Dr. Richard Corsi for one of our Research to Practice shows Episode 343
Dr. Brandon E. Boor is an Assistant Professor in the Lyles School of Civil Engineering at Purdue University. His research group at Purdue is focused on understanding the dynamics of airborne particles (aerosols) in buildings and human exposure to indoor air pollution. He teaches courses on indoor air quality and architectural engineering and advises the Global Air Quality Trekkers undergraduate EPICS team. He has previously worked with indoor air quality and aerosol research groups at the University of Helsinki, Finnish Institute of Occupational Health, and VTT Technical Research Centre in Finland, as well as the National Institute of Standards and Technology in Maryland. He received his Ph.D. from the Department of Civil, Architectural, and Environmental Engineering at the University of Texas at Austin in 2015.
Dr. Jelle Laverge (1984) received his engineering masters from Ghent University in 2007. From 2005 to 2007 he was a part-time employee of Bureau Bouwtechniek in Antwerp. Since 2007 he is a fulltime researcher and PhD-candidate at the building physics, construction and building services research group of the department of architecture and urban planning at Ghent University. In 2011 he received a master’s degree in Law from the same university. He was a part-time building physics lecturer at KaHo Sint-Lieven Gent for the 2011 spring semester. With the support of the FWO (grant V430911N), he was a visiting scholar at the University of Texas at Austin during the summer of 2011. With a dissertation entitled ‘Design strategies for residential ventilation systems’, he obtained a PhD in 2013. He is a member of ISIAQ, SRS and ASHRAE.
This week on IAQ Radio we welcomed Brandon Boor, PhD of the Purdue University and Jelle Laverge, PhD of Ghent University in the Netherlands. The discussion was focused on their recent paper titled:
“Human exposure to indoor air pollutants in sleep microenvironments: A literature review” Brandon E. Boor, Michal P. Spilak, Jelle Laverge, Atila Novoselac, Ying Xu
The paper is available on Dr. Boor’s website: http://www.brandonboor.com/pdfs/SleepIAQ_2017.pdf
Nuggets mined from today’s episode:
Brandon Boor and Jelle Laverge met at the University of Texas at Austin, where Jelle was a visiting scholar. Both Brandon and Jelle studied under Richard Corsi, PhD. Brandon Boor, PhD is now at Purdue University and Jelle Laverge, PhD is back at his alma mater Ghent University, in Belgium. Ghent University is one of two major universities in Belgium and is noted for Reproductive Science and in Gene Engineering. Jelle studied mechanical engineering and ventilation which he followed into IAQ. At the University of Ghent, IAQ falls under Building Science which is in the School of Architecture. Jelle is also an attorney specializing in Construction Law.
Brandon became interested in how particles become airborne and are transported and was inspired by Rich Corsi to do research in the area of the unique microenvironment during sleep, chemical exposure from children’s bedding.
The literature review was conducted primarily online using Science Direct, Web of Science, Google Scholar. They would search subjects such as “sleep and dust mites” or “sleep and flame retardants”. Older information was researched by following cited references. They both noted Dr. Corsi’s memory as an important research source. They wanted to tell a useful story and summarize what’s been done and show what needs to be done moving forward.
There is a large table on the biological composition of mattress dust from studies from Europe, Australia, USA and Asia. Studies from the early 1990s tried to link respiratory outcomes to chemical emissions. Gathering information from related field they describe conditions in sleeping environments, sleep surface variables, sleep exposure pathways (including dermal exposure) and characteristics, provide intervention strategies to further establish human exposure to indoor pollutants in microenvironments as a research field.
Because few field measurements in actual sleep environments in homes has been done due to the requirement for invasive sampling; dust is used as a surrogate to predict exposures during sleep. Brandon is concerned about the dermal exposure of infants to phthalate and flame retardant additives in crib mattresses while sleeping. He feels the exposure is potentially significant. Mattress covers which protect children from chemical emissions of mattresses are full of plasticizers. Blankets increase dermal concentration exposure. Sleep position influences concentration in breathing zone. Jelle noted that most exposure research has been done in active environments such as offices.
Breathing zone sampling is noisy and its challenging to sample in the human breathing zone. Jelle has experimented with sleep sampling by using breathing thermal mannequins. Brandon has studied and captured the impact of real sleep movements using human volunteers. Jelle has found that when covers are over the head during sleep that emission concentrations and fungi can be 30 times higher than when sitting in the middle of the room.
Mattress selections is based upon affordability. In the US there is a program called Green Guard. A Belgian Consumer Testing Report showed that emissions were similar from mattresses which cost $500 and $5000.
Key points from the abstract of the study that we addressed on this show.
We spend approximately one-third of our lives sleeping, yet little is known as to how human exposure to indoor air pollutants during sleep impacts human health and sleep quality.
This paper provides a literature review of the current state-of-knowledge pertaining to human inhalation and dermal exposures while sleeping.
An analysis of the duration of sleep exposure periods is provided, demonstrating that the sleep microenvironment is the predominant indoor space where humanity spends most of its time.
Mattress dust is found to contain a diverse spectrum of biological particles and particle-bound chemical contaminants and their concentrations in dust can span many orders of magnitude among bed samples.
These dust particles can become airborne through particle re-suspension associated with body movements in bed.
Mattress foam and covers, pillows, and bed frames can emit a variety of volatile and semi-volatile organic compounds, including phthalates, plasticizers and organophosphate flame retardants, and emission rates can increase due to localized elevations in surface temperature and moisture near the bed due to close contact with the human body.
This literature review demonstrates that human exposures to mattress-released pollutants can be amplified due to the source-proximity effect inherent to the sleep microenvironment, where the human body and breathing zone are in close and intimate contact with potential pollutant sources for prolonged periods.
Given the findings of this review, human exposures to indoor air pollutants in the sleep microenvironment should receive more attention and future research is needed to fully understand how sleep exposures affect human health and sleep quality.
A few thoughts from Radio Joe on converting research to practice after this interview.
How do you choose the right mattress or recommend the right mattress for your clients? Current research does not do a good job of answering this question and choosing a mattress is a crap shoot. One thought would to start with a low VOC mattress as rated through the Green Guard program. You may also consider recommending a traditional inner spring mattress for infants and toddlers to avoid the dermal exposure to volatile and semi volatile organic compounds, for adults a foam mattress may be a better choice.
A more important point seems to be how the mattress and associated bedding is used and maintained. Traditional spring mattresses appear to accumulate the most particulate, newer foam mattresses emit more volatile and semi-volatile compounds. Do not sleep with the covers over your head.
Regular HEPA vacuuming of the mattress and covers shows some potential for reducing exposure and regular washing in hot water continues to be recommended based on research to date.
Dust mite covers for beds and pillows continue to be recommended by public health officials and asthma and allergy docs and their related associations. This is particularly important for those with dust mite allergies.
Renovations, remediations and ventilation appear to improve the sleep micro-environment. Ventilation can be natural (crack a window) or mechanical but it should be present in sleep environments.
How often should we recommend purchasing a new mattress to improve the sleep micro-environment? This continues to be a tough question that has not been adequately answered by the available research.
The bottom line is, Indoor Environmental Professionals (IEP’s) should be paying closer attention to the sleep micro-environment of their clients. We will continue to report on this important IAQ issue!
Radio Joe signing off
What is the primary cause of sleep disruption for approximately 90 million American adults?
Snoring. the primary cause of sleep disruption for approximately 90 million American adults; 37 million on a regular basis