Denise L. Daggett, MS, CIH

The Scripps Research Institute

daggett@scripps.edu

Case Study Outline The Scene

The Situation

The “Resolution”

Results and Lessons Learned

Outrage Control

The Scene: The Scripps Research Institute (TSRI)

Academic research

> Million square feet of lab and office space

13 lab buildings

~500 fume hoods

100% fresh air

What is that smell?

How It All Began Late 2005 Reports of odors in our

large chemistry building Musty Grandma’s attic Wet dog, wet burlap, wet

money Locker room

Isolated to a couple of labs

Occurred around mid-day

Worsened through the winter months

Disappeared in April

Symptoms

Eye irritation Upper respiratory irritation Taste in mouth Headaches Nausea Mild to severe responses

Approached as an Indoor Air Quality Project Interviews Questionnaires Odor logs and phone calls to notify Air sampling Outrage escalated each time an episode

occurred Brought in consultants Offered medical evaluations with our

Occupational Medicine Physician

Additional Complaints In 2008, occupants in another lab

building reported same condition Always in the cooler months Same time of day Occupants would point to certain supply

grills as the source Some of our neighboring companies and

institutions were experiencing the same problems

Pinpointing Origin During an episode Entered the air

handler unit (AHU) feeding the lab

Odor present and very strong

Ah-Ha moment

Fact Finding and Data

Fact Finding Searched the literature Condition described as Dirty Sock Syndrome

Small HVAC units (cars)Residential unitsLarge AHUs (sport arenas)

Odor due to bacteria and mold growth on the coils

Employees want to know What the odor isWhat is flying through the air

No description of the actual chemical composition

The Experts Spoke to:

Harvard researcher – mainly bacteria with a biofilm, odor is metabolites from mainly bacteria

Houston engineer – salts, dirt, and microbial material

Montana State University – bacteria with a biofilm

TSRI Occupational Medicine Physician – typical indoor air quality symptoms, likely will not cause permanent harm

What is a biofilm?

Biofilm forms when bacteria

adhere to surfaces in aqueous environments and excrete a slimy, glue-like substance

can be formed by a single bacterial species, but more often consist of many species, debris and corrosion products

Other examples: plaque on teeth, slime on pet feed/water bowls

Information and figure courtesy of the Center of Biofilm Engineering, Montana State University

Sampling in an Air Handling Unit

Working Theories about Causation

ChemicalOxidized metalSaltsMoistureDebris from firesOther debris

BiologicalBacteria w/ biofilmMoldProtozoa

Biological and Chemical

Sampling and Data: Chemical

Method/Comments Results

MIRAN: unknown sample pulled into instrument cell and qualitative analysis against library

CO2 and acetone

SUMMA Canisters: taken inside AHU & lab, EPA TO-15 analysis

ppb levels of lab solvents: acetone, chloromethane, methylene chloride, toluene

Sampling and Data: BiologicalMethod/Comments Results

Air-o-Cells: indoors compared to outside

Very low counts of Aspergillus/Penicillium types and Cladosporium, Basidoiospores

Swab samples Bacterial: Moderate to high counts Bacillus speciesGram + and – rods, Gram + CocciFungal: low countsCladosporium, AureobasidiumExophiala, Acrodontium

Scrapings from inside air handler: looked like mold

No biologicals: high salts, metal oxides, and dirt

Biocassette samples: bacteria and mold, taken inside the air handler

No viable bacteriaNo viable fungi

Likely Not One or the Other but Both

Chemical Biological

Dew Point plays a role: When coil is damp, odor occurs. Is the smell from a wet coil (like wet pavement) or moistened biofilm?

What Now? Clean the CoilsDate Action Coil Position

April 2009 Low pressure rinse, mild bleach solution, then rinse

Removed hot and cold coils

January 2010 Water rinse, application of an EPA-approved coil cleaning product, then rinse

Remained in place

February 2010

Cross plumbed hot water to cold coil, heated it up to 180 F, then application of coil cleaning product, then rinsed

Remained in place

March 2010 Heated up cold coil, low pressure spray down, steam application, the use of a different EPA-approved biocidal material, then rinsed

Remained in place

Did the Cleaning Work? First cleaning

occurred in April 2009A few odor

complaints, then gone for several months

Back in autumn

Outrage of occupants continues to simmer

Managing the Outrage One-on-one

conversations Town hall-style

meeting Angry letters and

conversations Back to one-on-one

conversations to key individuals

Technical summit

The Future As predicted the odor

dissipated for the summer

Odor will return Back to experts again:

RFP issued Oct 2010 Bringing in

experienced personnel

Treatment needs to be ongoing

One Path - UV After 2009 cleaning,

a UV system was installed

No benefit noted 2010: a better

designed UV system installed

Benefit remains to be seen

Questions?

Biofilm and Biocide Clip

Movie Description:  

http://www.erc.montana.edu/Res-Lib99-SW/Movies/2005/05-M005.htm

This is a computer model simulation in which the hypothetical persister protection mechanism is active. Biofilm formation begins with the development of independent cell clusters that merge over time. An antimicrobial treatment initiated at 100 hours rapidly kills most of the live cells, but persister cells survive. When the persister cells eventually resuscitate, they give rise to new growth that begins in clonal pockets but rapidly extends throughout the biofilm.  Movie Authors:  J.D. Chambless, P.S. Stewart, S.M. Hunt

Reference:  Chambless, J.D., Hunt, S.M., and Stewart, P.S. 2006. A Three-Dimensional Computer Model of Four Hypothetical Mechanisms Protecting Biofilms from Antimicrobials. Applied and Environmental Engineering, 72(3):2005-2013.

 

http://www.erc.montana.edu/default.htm