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12:03:28 From cliff zlotnik : Trivia- Name the combination of 3 words by which hydroxyl radicals were originally called after their discovery?
12:07:10 From Ralph Froehlich : Reactve Oxygen Species
12:08:32 From cliff zlotnik : sorry incorrect
12:08:50 From Jillian Dunbar : Open Air Factor
12:09:57 From cliff zlotnik : correct Jillian send your contact info to: czlotnik@cs.com
12:16:14 From Kishor Khankari : How airflow patterns in a space affect the partition coefficient?
12:17:53 From Scott Armour : Q: when you say “chemicals”, do you mean “mostly VOCs”? 0 or are you including those chems that are also on aerosolized partculatuets
12:21:05 From Kishor Khankari : Where does the mass transfer coefficient factor in here?
12:31:03 From Kishor Khankari : When we purchase new furniture or other indoor materials, do we need to know partition coefficient? If yes, where can we find the values?
12:34:02 From Ralph Froehlich : How does Advanced Photocatalysis affect chemical air contaminants in indoor spaces?
12:37:17 From cliff zlotnik : Root cause of odor when using uvc disinfection. sanuvox.com
12:41:04 From Wane A. Baker : ASHRAE RP-1509 -- Study the Degradation of Typical HVAC Materials, Filters and Components Irradiated by UVC Energy
12:42:36 From Scott Armour : LOL I just used that example yesterday - if you dont remove it, when you step in it, you still get shit on your shoe!
12:48:44 From Scott Armour : Chemistry is very confusing to the layperson as well as the professional - for example, there was a trend a few years ago that claimed ammonia “denatured” (i.e., made safe) mycotoxins on surfaces. YET - the actual study that this idea came from showed that the ammonia broke the particular mycotoxin (removed a functional group) and result was another mycotoxin that was considered more reactive that the initial target molecule.
12:49:56 From Scott Armour : by the way, this claim remains in the mold-illness community and is repeatedly recommended by many different professionals, including doctors treating “mold mycotoxin illness”
12:53:04 From Scott Armour : I apologize I missed the intro regarding the book - is this now availabe?
12:54:52 From Alison Savage, EPA : Yes, you can download Why Indoor Chemistry Matters here: https://nap.nationalacademies.org/catal ... ry-matters
12:55:36 From Scott Armour : Alson -thank you
13:02:09 From Scott Armour : “Advanced” is a marketing term - from the hydroxyl companies that claim “low” or no ozone production
13:02:21 From Alex Madonik : So, does 100% mask use eliminate exposure? That’s the implication.
13:04:10 From Scott Armour : How do we contact Alison?
13:04:57 From LDOYLE : Savage.Alison@epa.gov
13:05:22 From Jim Newman, Newman Consulting Group : OMGosh, Scott, how can you say that about the word "Advanced"? Being facetious of course.
13:06:50 From Alison Savage, EPA : Yes - that's the correct email for me. Thanks!
13:06:54 From Scott Armour : Jim - lol
13:08:37 From Scott Armour : Question: what are the implications for employing the Precautionary Principle with regard to potential exposure
13:09:37 From Scott Armour : Joe - skin cells are in almost every air and indoor dust sample from anywhere - even in outdoor air!
13:10:01 From Victor Cafaro : IAQRADIO+ Afterthoughts
13:10:03 From Scott Armour : EXCELLENT so glad I joined today
13:10:22 From LDOYLE : Thank you!
13:10:41 From Steven Emmerich : Great job Alison, Bill and Dustin!

Episode 671| August 12, 2022 | 12:00 PM EST

William Bahnfleth, PhD, PE
Dustin Poppendieck, PhD
Alison Savage, MPH

Why Indoor Chemistry Matters! Part 2
Partitioning, Transformations and Management of Chemicals in Indoor Environments

This week we welcomed Dr. Bill Bahnfleth, Dr. Dustin Poppendieck and from EPA Alison Savage for part 2 of our series on the NASEM document Why Indoor Chemistry Matters! This week we focused on the Management of Chemicals in Indoor Environments.

Nuggets mined from today’s show:

Dustin Poppendieck- Dustin’s interest in indoor chemistry was piqued when he studied the cleanup effort of the Senate Hart building after it was attacked with anthrax. Researchers knew that when lethal levels of disinfectant were reached in the lab, the disinfectant killed anthrax spores. Dustin studied why lethal levels were not achieved in the Senate Hart building and found that disinfectant was consumed by surfaces preventing lethal disinfectant levels from being attained. When studying methamphetamine mitigation, he found that methamphetamine would migrate through latex paint. He also studied spray polyurethane emissions. He opines that indoor environments are chemical reactors. Building materials and home furnishings can be both sinks and sources. He has also studied cig butts and flame retardants. After touring the Net Zero House, Charlie Weschler contacted Marina Vance and Delphine Farmer to do experiments on: cooking, smoking, cleaning and surface aging at NIST. This resulted in the Chemical Assessment of Surface And Air (CASA) field campaign with 12 universities. Indoor chemistry is very complex.

Alison Savage- When consumer products are used indoors they can create new particles under certain circumstances. EPA recently published info on flooded home cleanup https://www.epa.gov/flooded-homes

Dustin Poppendieck- Partitioning 3.2
Partitioning is accounting, keeping track where chemicals are. Using the analogy of keeping track of people at an oceanside beach. Partitioning coefficients are similar to how many people are on the beach compared to how many people are in the water? Partitioning coefficients are not related to time. Temperature, rain and humidity can influence how many people are on the beach and how many people are in the water. Partitioning is both chemical dependent and environmentally dependent. Surfaces affect partitioning, sandy beach versus rocky beach. Capacity is the big picture, how many people on a beach in Florida versus how many people on a beach in Alaska? Chemicals are distributed by air and partition to everything. Chemicals can be in solid, liquid, or gas phase. Partitioning controls how things happen. Partitioning is an equilibrium situation. What is in one material versus another, residues can build up. We want to remove things from the air.

Bill Bahnfleth- Picking up on Dustin’s analogy, there are many people on the beach and a few in water. Sharks, may catch a few swimmers in the water, but there are still a lot left on the beach. Using ventilation to remove chemicals that are in much higher concentration on surfaces and in materials is similar. Hazardous chemicals can partition onto surfaces and into solids. Control methods include: flush chemicals into the air (works well for some, not well for others like SVOCs), clean surfaces or replace materials. 3rd hand smoke from tobacco or fires is an example of a reservoir created by partitioning from the air.

Dustin Poppendieck- There is a wide range of chemical partitioning: SVOCs, PAHs, methamphetamine. Chemical migration may occur at a very low rate. It takes a long time to lower the reservoir. Reservoirs are brought into the home such as carpet cushion, and upholstery foam. Chemical migration from deep within material such as urea formaldehyde foam takes a long time. Recently applied chemicals (smoke event or cooking) migrate much faster from surfaces. Relatively large surface area per unit volume surfaces can be important reservoirs.

Bill Bahnfleth- Surfaces and materials sorb and desorb. Whether contaminants are being removed from air or added to it can depend on temperature and humidity variation.

Dustin Poppendieck- An increase in temperature of 10° C doubles the emission rate. Water vapor can be different: from only a few water molecules layered together to a puddle. The concentration of hydrophilic substances is lower at higher RH. The concentration of hydrophobic substances is higher at higher RH.

Bill Bahnfleth- The effect of air flow on chemical emission rates is similar to the effect of air flow on heat loss. A fan cools skin by increasing heat transfer and the heat transfer at the skin surface goes into the air.

Dustin Poppendieck- Chemical transformation is any process that leads to the loss or removal of something. Multiple baking ingredients go into baking a cookie. Once the cookie is baked the baking process cannot be reversed. However, in a chocolate chip cookie, the chips may be removed and the transformation process reversed.

Bill Bahnfleth- HVAC ductwork have high potential to sorb chemicals in their gas phase. The public often doesn’t realize that the products we bring indoors cause chemical processes to occur.

Alison Savage- Certain activities such as cooking, cleaning and increasing ventilation may result in greater potential for indoor chemical transformations by increasing concentrations of certain drivers of indoor chemistry. For example, bringing in more outdoor air increases O³ levels indoors, by drawing in more O³.

Dustin Poppendieck- We don’t know what happens chemically when we use disinfectants indoors.

Managing Odors Indoors:
Where is the odor emitting: surface or airborne?
What are the biggest reservoirs: carpet cushion, upholstery, walls, floors, etc.?
Naturally, ventilation cannot solve all IAQ problems. Sometimes source control is the best method: “If there is a pile of manure in a space, do not try to remove the odor by ventilation. Remove the pile of manure.” (Max von Pettenkofer, 1858.)
A viable technique in one place may be irresponsible in another.
ASHRAE has studied reactions between O³ and human skin oils.

Bill Bahnfleth- We need to consider chronic occupant and worker exposures. Need an actionable definition of indoor air quality – which contaminants to monitor and what levels are acceptable. There could be thousands of chemicals in an indoor environment and we can’t track all of them. To get to a manageable number, We need to calculate and rank the risks posed by the most common chemicals at typical exposure levels if we are ever going to solve the problem.

Hierarchy of controls figure 5.1

The management of chemical contaminants in indoor environments includes removal (through ventilation, filtration, sorption, physical cleaning, and passive surface removal) and chemical transformations (including photolysis, ionizers, chemical additions, and photocatalysis). No single management approach can remove all contaminants that are present indoors; therefore, source elimination is always the preferred method of control. Buy safe, certified products that meet industry safety standards. Furnishings can be both source and sinks.

ROUNDUP
Bill Bahnfleth- Summer Camp
Demonstrated ASHRAE Covid recommendations in meeting room holding 500 people.
• Inspected HVAC system and found fresh air intakes closed, had to tape intakes open.
• Upgraded HVAC filers from MERV 8 to MERV 13, needed to do “filter origami” in order to get filters to fit in racks.
• Built Corsi-Rosenthal cubes
• Installed portable UVC lights
• Measured CO² (maximum was about 1200 ppm, indicating OK ventilation per ASHRAE Standard 62.1)

Alison Savage- EPA goals are to ID pollutants of concern and mitigate to protect vulnerable communities and populations. COVID increased the public interest in IEQ.
Greater interest in IEQ in schools.

Dustin Poppendieck- We spend 90% of our time indoors. So 90% of our chemical exposures are indoors. COVID was the silver that raised public awareness of IEQ.
We don’t understand what is good and bad indoors
We don’t understand the significance of indoor chemistry as a problem
We don’t have all the answers.
We must communicate the information to vulnerable communities.

Bill Bahnfleth- There is much we don’t know. National Academy Committees are researching and working on the problem. However, we already know enough to make indoor environments better. We need to communicate what we know about indoor chemistry to building operators and occupants. Building operators need to know more about indoor chemistry.

Z-Man signing off

References:

Why Indoor Chemistry Matters
https://nap.nationalacademies.org/catal ... ry-matters

ASHRAE OR-16-C033
Root Cause of the Odor Generated by Germicidal UV Disinfection with Mobile Units
https://standards.globalspec.com/std/10 ... OR-16-C033

Scope:
Germicidal ultraviolet (UV) light has long been used successfully for the disinfection of water, air, and surfaces, and has become a common practice in the healthcare industry. There has been, however, an unresolved health concern with regard to the residual odors that have often been noted after rooms have been disinfected, and no satisfactory explanation of these possible volatile organic compounds (VOCs) has previously been published. This study explains the residual odors in terms of thiol or mercaptan molecules that can be produced by the UV irradiation of keratin and cysteine. Keratin is a protein that is found in skin squames while cysteine is a similar molecule found in hair. They also both contain a significant amount of sulfur. Skin squames and hair particles are common contaminants of indoor environments and are present in airborne dust as well as being surface-borne. UV photons carry sufficient energy to break the chemical bonds of keratin and cysteine, as well as the chemical byproducts including volatile smaller sulfur-containing molecules that fall into the categories of thiols and mercaptans. The human nose is extremely sensitive to these molecules and can detect them at concentrations as low as 1 part per billion. The smell after UV disinfection is sometimes described as that of burning hair or the pungent odor of rotten eggs or garlic. The latter smell is characteristic of mercaptans. In an indoor environment where the dust loading in the air may typically be about 100 μg/m3(0.000044 grain/ft3), the aftermath of the UV disinfection process will leave behind a concentration of mercaptans of about 2 ppb, or twice the smell threshold level. According to the CSST in Quebec and per OSHA, the safe level for 8 hours of exposure to mercaptans is 500 ppb. Consequently, the actual level obtained after UV disinfection is negligible and therefore it is concluded that the VOCs responsible for the residual odor after UV disinfection do not pose a health hazard to humans.

The hard part about dealing with indoor air chemistry is figuring out what is wrong and then how to solve the issue. The report from NASEM is a great start to learning more about this topic. There is still a lot to do but at least now we have a foundation to build on.