Air Date: 2-27-2015 | Episode: 358
Dr. Siegel is an Associate Professor in the Department of Civil Engineering and the Dalla Lana School of Public Health at The University of Toronto…
Dr. Siegel is an Associate Professor in the Department of Civil Engineering and the Dalla Lana School of Public Health at The University of Toronto. Prior to accepting his current position he was an Associate Professor at the University of Texas, Austin. His interests and research have focused on healthy and sustainable buildings, ventilation and indoor air quality in residential and commercial buildings, control of indoor particulate matter, secondary impacts of control technologies and strategies, aerosol dynamics in indoor environments and HVAC systems. He is also keenly interested in ensuring that good research works its way into practice and this week we want to focus on that theme. Dr. Siegel’s Ph.D. is in Mechanical Engineering (2002) from the University of California, Berkeley, he also has an M.S. in Mechanical Engineering (1999) from the same institution and a B.S. in Engineering (1995) from Swarthmore College. He is a prolific researcher and speaker and a very active member of professionals societies and associations including ISIAQ and ASHRAE. We look forward to LEARNING MORE with him this week on IAQ Radio!
Filter forensics and more
Jeff Siegel, PhD associate professor at the University of Toronto was today’s guest on IAQradio. A summer job while a college undergrad piqued his interest in energy conservation which expanded to an interest in and study of IAQ in graduate school.
Nuggets mined from today’s episode:
- IAQ is neglected when compared to energy conservation. Research funding and national priorities are focused on energy efficiency. A reason for the focus on energy efficiency is savings are reflected in next utility bill, while IAQ benefits are realized in the future.
- OZONE (Ois a complex subject. Ozone in the atmosphere blocks and absorbs UV. UV light passes through the hole in the ozone layer. Ozone is highly chemically reactive. Ozone is the most prominent oxidizer in indoor air. Ozone is effective as a sterilizer in labs and medical applications, in these applications Ozone is vented outside. Ozone should not be used in occupied environments. There are no positive or health benefits in using ozone Ozone reacts with background chemicals forming secondary products/new compounds. Ozone reacts with skin oils. O+ terpenes (found in fragrances and cleaning products) = formaldehyde, carboxylic acid and ultrafine particles. Ohas some odor removal applications in fire restoration.
- HYDROXYL RADICALS. There is no consistent terminology for hydroxyl radical devices. Like O, hydroxyl radicals can react with background chemicals to form byproducts/unwanted new compounds. Testing devices sold as “air cleaners” has demonstrated the emissions vary between models. Devices which emit Ozone or hydroxyls should not be called air cleaners.
- Terminology such as “activated oxygen” used in conjunction with ozone and/or hydroxyl generators confuses consumers.
- Air filters remove from air things we don’t want to breathe. Energy cost consequences of improved air filtration are small when compared to the value of improving health, productivity and IAQ. Energy savings are noticed quickly as contrasted with IAQ benefits which occur over the long term.
- Guessing about energy savings, power meters quantify what is really happening.
- HVAC fans slow down when operating with higher efficiency filtration. Slower moving fans actually use less energy.
- Slowing fans may cause icing of cooling coils and heat pumps.
- Icing is often caused by poor HVAC system design and/or systems with insufficient airflow and over or under charged refrigerant. Pay more attention to HVAC design, operation and maintenance.
- Soiled air filters often smell because they are laden with microorganisms and odorous compounds such as ozone reactants/aldehydes.
- While filters remove airborne contaminate, contaminate impacted in filters does remain within airstreams until filters are changed.
- Be careful not to cross contaminate during filter change and equipment maintenance.
- While higher pressure drop filters may use a little more energy in residential and commercial rooftop applications, the small additional energy expense pays big dividends in improving IAQ and occupant health and comfort.
- We should think about everything we are doing due to secondary consequences.
- FILTER FORENSICS. Researchers have been studying HVAC filters since the 1950s. Historically system filters were studied in the context of infectious disease. In these scenarios, industrial hygienists would collect samples and culture to look for microbes that were causing problems. System filters in central HVAC systems are a rich resource and can be used to study, analyze and understand human exposures. Occupant exposure to anything bound to particles can be determined from analyzing filters. Soiled filters provide large volume samples. 30 day sampling intervals can be used to quantify exposure.
- New DNA culture based research methods are being used to study air filter dust. New concerns include: semi volatiles, heavy metals, plasticizers, flame retardants and allergy/asthma triggers.
- Lead in dust from filters reflects the age of home. Cadmium found in dust indicates occupants were cigarette smokers. The characteristics of dust are different in high density versus low density occupancy.
- Wild fires and industrial accidents often release plumes of contaminate. Residents outside the immediate area are often told to stay indoors and protect themselves from air outdoors. Analyzing HVAC filters following the Fukushima meltdown led to medical decisions as to priority of treatment. The sky is the limit on filter forensics. Some analysis is high cost while other analysis is low cost. Lead testing is low cost and may be correlated with other substances.
- Some analytical sampling methods are only snap shots in time. More traditional analytical methods can provide an integrated history of exposure which can be backed out. MERV 7/8 is a good balance filter for filter forensics. It is desirable to select filters from which dust is easy to extract.
- Research is being done on catching and stabilizing short lived materials such as gases on filters for latent recovery.
- “Microbiome | Define Microbiome at Dictionary.comreference.com/browse/microbiome Biology. the totality of microorganisms and their collective genetic material present in or on the human body or in another environment:”
Our bodies have more bacterial cells than human cells. We are surrounded by microbes. We don’t know how microbes effect exposure pollutants. Microbes may protect us or may hurt us. Air sampling and culturing is a time honored tradition. Some microbes are culturable while others are not. Only .1% of microorganisms are culturable so the vast majority of what organisms are present is missed.
- Sanger sequencing, is a DNA sequencing method developed in 1977 that was widely used for over 20 years. Pyrosequencing DNA is easier to use and tells less about individual organisms and more about the total community. qPCR, Polymerase Chain Reaction is a molecular biology lab technique used to amplify or detect a targeted DNA molecule. qPCR is reliant upon knowing what you are looking for and the use of primers. DNA technology isn’t currently widely useful for analyzing dust because only a narrow relevancy is studied. Luminous DNA sequencing looks at DNA and compares to an existing library of data. Culturing is often the right approach.
- More collaboration between practitioners and researchers is needed.
- Research to determine whether we should study broad ranges or narrow ranges of microbes and which microbes to encourage and which to discourage.
- DNA sequencing provides an abundance of information, which is of no consequence. It denotes what is present not how much of it.
- In our lifetime we will design buildings to have healthy communities of microbes.
Emerging issues for practitioners:
1) Moisture indoors- mold isn’t the problem but rather an indicator of an underlying moisture problem.
2) You can’t have a sustainable building unless everything needed to have a sustainable building is done.
3) Ultrafine particles PM .1< are an emerging contaminant.
4) Semi-volatile compounds plasticizers and flame retardants are contaminates of concern.
5) If we believe everything may be causing harm-limit exposure before regulation.
6) Spray form insulation is a wonderful product for insulating and stopping unintentional airflows. Flame retardants comprise a high % of spray foam. Assume the risk of flame retardants by temporarily putting homes under positive pressure after foam insulating and meticulously cleaning up dust.
7) Being overly cautious is the worst that can happen-protecting people is the best that can happen.
8) Educating the public is the biggest challenge. Getting the word out raises awareness, increase interest and motivation.
Today’s Music: Magic System- Magic In The Air. Chawki
Z-Man signing off
What is the origin of the word forensics?
Answer: Latin forensis, meaning “of or before the forum”