Episode 690: Connie Araps, PhD & Kishor Khankari, PhD - Advances in Reactive Indoor Air Cleaning Technologies

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Show Discussion:

11:57:36 From Don Weekes : AOC - Advanced Odor Control
12:00:23 From Don Weekes : No, that is why I am here today.
12:01:25 From Don Weekes : I saw Kishor in the halls. It is always good to see Kishor.
12:04:00 From Don Weekes : Tesla
12:04:34 From cliff zlotnik : correct Don!!!!!!
12:23:50 From John Pletcher : Is there any data that has established the PEL for hydroxyls? How is the output level of hydroxyls measured? And how is that level adjusted in these machines?
12:30:25 From Tom Peter : Similar question, we use hydroxyl generators in the restoration industry, for smoke odors, mold odors, etc... most common units used are the Odorox units with Pyure Technology. The manufacture states that it is perfectly safe to use in occupied areas. Is this true, using these large commercial hydroxyl generators in occupied areas is safe?
12:32:22 From Robert (Brookline, MA) : OH - Free Radical that combines with contaminants to neutralize the toxic, chemical, biological, etc., contaminant?
12:33:08 From Tom Martin III : will installing the machine in the kindergarten class room help address CDC recommendation for temperature (68-72)and humidity (35-50%)parameters in order to help kids and employees with asthma and allergies ?
12:37:02 From Ralph Froehlich : How does one measure the hydroxyl radical concentration or subsequent radical concentrations?
12:38:09 From Ralph Froehlich : When can one tell when too high of a hydroxyl concentration is being produced?
12:38:59 From John Pletcher : I too have used Odorox machines in fire restoration and after running a machine in a residential setting I noticed the air in the room became cloudy. I was told this cloudiness is related to ultra fine particles that either were produced by the hydroxyl machine or something in the room reacted in a negative way with the hydroxyls. Can you comment on that?
12:44:04 From Tom Martin III : Some folks managing lung disease and respiratory challenges are not able to use ionization units they complain about health effects..
12:50:34 From Ralph Froehlich : How can a building manager compare different types of hydroxyl generators? Are some more efficient than others?
12:52:03 From Ralph Froehlich : What is a “normal use” condition for a test chamber?
13:01:01 From John Pletcher : I can sometimes detect low levels of ozone when running my Hydroxyl generator, is ozone produced by the UV lights that produce the hydroxyl radicals?

[CliffZ]

IAQ Radio Episode 690

Connie Araps, PhD & Kishor Khankari, PhD
Advances in Reactive Indoor Air Cleaning Technologies

Good Day and welcome to IAQ Radio+ episode 690. This week we welcomed Dr. Connie Araps, PhD and Dr. Kishor Khankari, PhD to discuss their recent presentation at the ASHRAE Winter Conference called Advances in Reactive Air Cleaning Technologies. LEARN MORE on IAQ Radio+.

Dr. Connie Araps has an extensive background in chemistry, semiconductor technology and advanced engineering for manufacturing. She has a B.S.in chemistry from Rutgers University and a Ph.D. in organic chemistry from Princeton University. Dr. Araps is currently the president of Prometheus Strategies, which provides chemistry consulting services to companies in the field of advanced air and surface cleaning technologies. She is also a consultant to The Pyure Company and the Chair of Pyure’s Scientific Advisory Board.

Dr. Kishor Khankari is the president and founder of AnSight LLC. He is a specialist in Computational Fluid Dynamics (CFD). A noted expert in his field, he has a Ph.D. in CFD from the University of Minnesota and has regularly published in several technical journals. Dr. Khankari is an ASHRAE Fellow and Distinguished Lecturer. He is also currently serving on the ASHRAE Board of Directors.

Nuggets mined from today’s episode:

What is Photohydrolytic Hydroxyl Oxidation (PHO) and how does it work? Connie Araps
a. PHO uses ultraviolet energy to cleave water vapor to generate hydroxyl radicals HO. Hydroxyls are powerful natural oxidants formed by the action of the sun that sanitize air and surfaces by decomposing VOC and killing microorganisms.
i. Hydroxyl devices sustain this dynamic indoors. They abstract Hydrogen atoms from ambient VOC to form organic peroxy radicals ROO, powerful oxidants which are stable enough to circulate throughout the treatment space via a series of chain reactions with successive VOC. Typical ROO radical chain “lifetimes” are 12 minutes.
ii.
• How would you describe PHO to a child? Connie Araps
PHO machines use special lightbulbs to make chemicals to clean and purify indoor air in the same way that the sun cleans and purifies outdoor air.

• How PHO is different than other reactive air cleaning technologies? Connie Araps
a. PHO devices are designed to generate a single, natural oxidizing agent: the hydroxyl radical. They are designed to maintain the same concentrations of hydroxyls and organic peroxy radicals found outdoors: 1-3 million OH/cm3.
i. Because OH and ROO have such high oxidation potentials and fast reaction rates, they rapidly decompose VOCs and kill microorganisms by radical chain reactions.
ii. The oxidation by-products they generate are also rapidly decomposed and do not accumulate. This is the same process that is going on outdoors.
b. Other reactive air cleaners generate sanitizing agents differently.
i. PCO devices coat surfaces with catalysts like TiO2 which adsorb contaminants and decompose them by activating the catalyst with UV energy to generate oxidants.
ii. Ionizing devices use electrical energy to generate positive and negative ions, which serve two functions
1. They ionize particulates causing them to aggregate making it easier to filter.
2. The ions also decompose VOC and microorganisms by ionic chemical reactions.
3. Are very effective improving filtration of even 2.5 u size particles because ionized particles aggregate and the larger the aggregate the easier it is to filter. Ions can decompose VOC and kill microorganisms but the efficacy declines as a function of distance from the source. Published values for ion lifetimes are 1-2 minutes.
iii.
1. There are no device standards for ion concentrations. Natural levels range from 200-500 ion/cm3.

• What are the pros and cons of various reactive air cleaning technologies? Connie Araps

Hydroxyl generators
• Pros
a. Generate the same oxidants and in the same concentrations as found in nature, where they are the primary environmental sanitizing agents.
b. Because they have the highest oxidation potential of any chemical other than elemental fluorine, and exceedingly high reactions rates they decompose by-products quickly so they do not accumulate.
c. Toxicology studies conducted according to FDA guidelines (GLP 21 CFR Part 58) have shown that animals exposed to 2-3 times higher concentrations than normal over the requisite 13 weeks showed no negative effects either at the gross or cellular level.
• Cons
a. Generate oxidized VOC – alcohols, aldehydes, ketones, acids
b. Generate low ppb levels of ozone: published formation rate was 0.041 g/hr.
c. Does not filter.

PCO Devices
Pros
• Use a range of UV energy to activate the catalyst that generates no ozone.
• Most oxidants consumed by reactions with adsorbed contaminants

Cons
• Low MW VOC and oxidation by-products do not bind well to the catalyst and accumulate.
• The catalyst is deactivated by adsorbed water and the accumulation of carbonized VOC.
• Scalability is limited by the catalyst surface area.
• Catalyst degrades producing fine particles of catalyst and carbonized VOC

Ionizers
Pros
• The main advantage is that they cause particles to aggregate, improving filtration, especially for very small particulates.
• They also decompose VOCs and kill microorganisms by ionic chemical reactions.
• Agglomerate and improve performance of filters.
d. Disadvantage
i. Ion concentration and efficacy decreases as a function of time and distance from the source.
ii. Ion lifetimes are short: 1-2 minutes, so high concentrations of ions in the range of 20-40 K/cm are required to treat large spaces. While, natural ion levels are ~200-1500
iii. Most test data is done at lower ion concentrations of 2500-5000 ion/cm3.
iv. Use of electrical energy generates ozone, minimized by methods such as needle point ionization and non-thermal plasma generation
v. Generate VOC oxidation by-products can accumulate


• Where PHO has been deployed and what is the outcome? Connie Araps
Many vertical markets
a. Fire/Flood restoration: mold, odor (Service Master, Servpro, Aramsco, etc.)
b. Industrial plants, water treatment: VOC and odor mitigation (Toyota, Cargil)
c. Hospitals, ambulances – Surgery, procedure rooms (Steris, Mastel Surgical)
d. Elder Care (Cambridge House)
e. Schools: NJ school systems
f. Food, meat and beverage processing - Indian
g. Office space, data centers, commercial spaces to minimize the spread of infection and eliminate odor
h. Casinos – odor and smoke mitigation (Carnival, Churchill Downs)
i. Hospitality – Lowes, choice….etc.)
j. Military – Camp Lejeune

WE ARE AWAITING ANSWERS ON THESE QUESTIONS:
• I have used Odorox machines in fire restoration and after running a machine in a residential setting I noticed the air in the room became cloudy. I was told this cloudiness is related to ultra fine particles that either were produced by the hydroxyl machine or something in the room reacted in a negative way with the hydroxyls. Can you comment on that? Connie Arap
• I can sometimes detect low levels of ozone when running my Hydroxyl generator, is ozone produced by the UV lights that produce the hydroxyl radicals? Connie Arap
• The manufacture states that it is perfectly safe to use in occupied areas. Is this true, using these large commercial hydroxyl generators in occupied areas is safe? Connie Arap
• Is there any data that has established the PEL for hydroxyls? How is the output level of hydroxyls measured? And how is that level adjusted in these machines? Connie Arap
• How can a building manager compare different types of hydroxyl generators? Are some more efficient than others? What is a “normal use” condition for a test chamber? Connie Arap
• Knowing that the species of chemicals generated by your device are highly reactive and after only testing your devices in test chambers, how can you be sure that your devices are safe for use in occupied environments containing unknown levels of background chemicals and fire related residues? Connie Arap

Device Pricing? Connie Araps
• A base typical package can start anywhere from under $1000 to $3000 depending on space and requirements. Pricing is dependent upon the size, number of optics and fan/blower.

• Where PHO cannot be applied? Connie Araps
a. Not applicable to high ppb concentrations of VOC
b. Rapidly moving air streams in industrial plants, stacks

• Separating Fact from Fiction Kishor Khankari
Consumers may choose from a variety of air cleaning technologies and devices. With all of the manufacturers claiming that their device is best; the need exists to bring engineers and chemists together to discuss air cleaning devices, create uniform testing methods and develop industry standards.
Kishor chaired a panel of manufacturers at the ASHRAE winter conference. ASHRAE has formed a committee which will lead to the development of uniform test methods and industry standards.

• What is the role of CFD? Kishor Kahnkari
PHO devices involve heavy chemistry. PHO devices release sanitizing agents into the air in indoor spaces. PHO devices can be an alternative to dilution. PHO devices dilute and reduce target contaminate counts. The life of the agent is critical as the agent needs to get into the breathing zone of the occupants,

“Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to analyze and solve problems that involve fluid flows. Computers are used to perform the calculations required to simulate the free-stream flow of the fluid, and the interaction of the fluid with surfaces defined by boundary conditions.” Wikipedia

Currently there is no standard method for testing air cleaning devices. CFD can be used to model the way various air cleaning technologies work and the effect the technology has in the room in which it being applied.

Air is the carrier for airborne reactive agents. CFD can: demonstrate what is happening in occupant breathing zones, demonstrate how infection spreads indoors, determine probabilities of infection, demonstrate the effects of increasing or reducing fresh air dilution, etc.

• What is the future of reactive air cleaning? Connie and Kishor
a. Reactive air cleaners address the growing concern about the risk of transmitting infections in occupied spaces because they are dynamic and interact with pathogens in real time in the breathing zone.
b. Disease transmission significantly reduced indoors when integrating reactive air cleaners with HVAC compared to using ventilation alone

• What testing standards are needed in this space? Connie and Kishor
Standards for testing to evaluate efficacy and safety
Efficacy
• Methods for quantitatively measuring reactive agent
i. formation rates
ii. lifetimes
iii. kill rates of pathogens in air and surfaces
b. Methods for measuring changes in VOC concentrations
c. Methods for microorganisms testing which specify
i. Testing in licensed third-party labs
ii. Using industry standard techniques, guidelines
iii. Testing chamber size
iv. Use of commercial devices sized for the test chamber operating at normal use conditions
Safety
• Standards for measuring steady state VOC concentrations
• FDA GLP Toxicology studies

Suggesested by the Z-Man-
Marketing & Advertising is like the wild, wild west and needs uniformity, hopefully standards will do that.
Uniform marketing terminology
“The dose makes the poison” when is too much, too much?
What is the Permissible Exposure Limit.

Z-Man Signing Off

Trivia Question:

Name the holder of a patent for a device “to provide a simple, cheap, and effective apparatus for the production of ozone or such gases as are obtained by the action of high-tension electrical discharges?

Answer: Nikolai Tesla
Answered by: Don Weekes, Ottawa, Ontario Canada

[RadioJoe]

I am sorry that I did not get to some of these very good questions from the chat on Friday. Unfortunately I was flying blind as my laptop that I use to monitor the chat needed an extremely large microsoft update. Yes I should have done that before the show but sometimes I forget to turn on the laptop I only use for the show.

Anyhow we scheduled a part 2 specifically to answer these questions and others I have gotten from past guests. We will let everyone know when this is rescheduled.

In the mean time my thanks to this week's guests it is a fascinating topic and it is NOT going away so we need to continue to figure it out.