Transcript Biological
Denise L. Daggett, MS, CIH The Scripps Research Institute [email protected] 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 midday 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 units Large AHUs (sport arenas) Odor due to bacteria and mold growth on the coils Employees want to know What the odor is What 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, gluelike 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 Chemical Oxidized metal Salts Moisture Debris from fires Other debris Biological Bacteria w/ biofilm Mold Protozoa Biological and Chemical Sampling and Data: Chemical Method/Comments Results MIRAN: unknown sample pulled CO2 and acetone into instrument cell and qualitative analysis against library SUMMA Canisters: taken inside ppb levels of lab solvents: AHU & lab, EPA TO-15 analysis acetone, chloromethane, methylene chloride, toluene Sampling and Data: Biological Method/Comments Results Air-o-Cells: indoors compared to Very low counts of outside Aspergillus/Penicillium types and Cladosporium, Basidoiospores Swab samples Bacterial: Moderate to high counts Bacillus species Gram + and – rods, Gram + Cocci Fungal: low counts Cladosporium, Aureobasidium Exophiala, Acrodontium Scrapings from inside air handler: No biologicals: high salts, metal looked like mold oxides, and dirt Biocassette samples: bacteria No viable bacteria and mold, taken inside the air No viable fungi handler 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 Coils Date 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 EPAapproved coil cleaning product, then rinse Remained in place February 2010 Cross plumbed hot water to cold coil, Remained in heated it up to 180 F, then application place of coil cleaning product, then rinsed 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 2009 A 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 http://www.erc.montana.edu/Res-Lib99SW/Movies/2005/05-M005.htm http://www.erc.montana.edu/default.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.