Whittaker Powerpoint June 08

Applications of the Opticle Particle Counter in an IAQ Assessment Columbia SC Chapter IAQA Workshop June 26, 2008 Presented by: Craig Whittaker, CIE, Ph.D. Environmental Solutions Group

Brief History of the Particle Counter
Parallels the development of the personal computer
First developed in the 50s to monitor dust in manufacturing

Evolved into a tool for assessing clean rooms
Greatest design advances made in last few years

The IAQ professional now has several options for small, powerful and intuitive devices that offer real-time data logging & other features

Most airborne particles are either biological contaminants, gases or dust
Handheld particle counters today are well-equipped for measuring airborne biological contamination
Current Technology

Biological contaminants include:
Mold
Dust mites
Viruses
Animal dander
Bacteria
Pollen
Skin fragments
Insect parts

Recent Studies on the Health Effects of Fine Airborne Particles European study found that fine particles that are inhaled can affect the blood vessels, leading to an increased risk of heart disease - American Journal of Respiratory and Critical Care Medicine Children with asthma had significantly decreased lung function following exposure to indoor air pollution that included fine airborne particles - National Institute of Allergy and Infectious Diseases

How Does the Particle Counter Work?
Counts particles that block a beam of light reflecting onto a screen

The three components of a particle counter: 1) airflow system 2) optical system 3) electronics

The Airflow System
Includes an isokinetic probe, air chamber and pump
Its job is to capture a sample of moving air at the same velocity it is moving, allowing a normalized count

The Optical System
Includes a high-grade laser, optical measuring components and a detection surface (screen)
Its job is to measure the scattered light against the screen

The Electronics
Includes computerized amplification and
counting circuitry
Its job is to amplify the low level signals from the detector surface and convert each scattered light pulse to a number representing its corresponding size

Tabletop vs. Portable Unit
Tabletop unit has a larger pump and can attach to multiple sensors throughout an area for continuous monitoring of clean rooms
Portable unit is designed for point-of-use measurements in critical locations to include clean rooms, medical facilities and HVAC systems analysis in commercial & residential buildings

One of the most useful aspects of the portable unit is the ability to track contamination - everything from fine dust to biologicals - to the source

One of the most common applications of the portable unit is for measuring the efficiency of filtration systems

Limitations of the Laser Particle Counter
Refracted light varies due to differences in particle shape & shininess
Particles are not always evenly distributed throughout a room
The electronics employ a bell-curve (Gaussian) distribution method of categorizing particle sizes

Guidelines for Use
Store unit at room temperature in a
vibration-free environment
Keep unit clean per manufacturer’s instructions
Stay clear of electrical equipment while collecting readings
Consider keeping a log of preventive maintenance, recalibrations and any unusual performance

Application: Trend Analysis
Noting gradual or sudden changes in airborne contamination when an HVAC system is powered on/off 1
Establish baseline readings prior to a process that may change the indoor air environment
Monitoring filter efficiency by sampling air immediately before entering & after entering the filter
1 NADCA’s ACR 2006 contains particle profiling procedures for HVAC systems

The single most important advantage of the handheld particle counter is the ability to conveniently collect multiple readings in an area to generate a statistically valid sample based on the average particle counts for the area.

Case Study #1: Outpatient Surgical Center
Two operating rooms and sterilization and surgical preparatory rooms flooded with clean water over a weekend. Water soaked floors and drywall.
Our firm arrived immediately after standing water was extracted to collect baseline (first-response) airborne particle readings prior to installation of HEPA air scrubbers.

Safety was of primary importance to the client but speed of remediation was also crucial. The remediation and reconstruction had to be complete and post-remediation verification obtained in only 48 hours
Handheld particle counters were used extensively to monitor the effectiveness of air scrubbers

Particle counts were recorded at entering and exiting points of twelve air scrubbers
Scrubber positions were adjusted frequently to address ‘hot spots’ where counts had spiked

Every phase of the project was guided in part by the particle readings
The remediation was completed ahead of schedule and particle counts were excellent. All that remained to be installed was the new flooring.

The ‘sterile’ vinyl arrived in the back of a filthy truck
Particle counts jumped nearly 7000% in the operating rooms upon bringing the vinyl into the rooms

The floors were finished at midnight with the rooms scheduled to open at 7:00 am.
We logged airborne particle counts until 5:30 am; counts were low enough to indicate a successful clearance

Spore counts were collected for lab analysis in one hand while re-checking particle counts in the other hand

Rush analysis by a local lab confirmed
that no fungal spores were present
in the operating suite.
Surgeries were performed on schedule and the client was relieved

Case Study #2: Physician’s Residence
A medical doctor who recently purchased a 100-year-old home on the NC coast had experienced flu-like symptoms since moving in two months ago
His wife and child have no symptoms, but they sometimes noticed a musty odor on the main level
A visual assessment yielded no moist building materials or fungal growth inside the home

Airborne particle counts were abnormally high in the 2.5- µ m classification in the kitchen. After ruling out food items as the source, we collected a particle reading in a base cabinet and found the 2.5 - µ m count to be 700% higher than the average count for that size particle elsewhere in the house

The culprit appeared to be gold-colored material on an exterior plaster wall in a base cabinet where cooking items were stored. We removed several items to expose the material for sampling & for taking this picture.

Lab analysis indicated an elevated count of 2320 aspergillus/penicillium spores/m 3 in the total spore count. An air culture indicated a count of 320 cfu/m 3 of aspergillus.
The physician/homeowner was subsequently tested and found to have a fungal infection in his digestive tract. Remediation and antibiotics have resolved his medical issue.

Case Study #3: Office Building
An employee at a call center that had experienced a water leak from the HVAC system one year ago was taken to the hospital after cleaning under her desk. She developed a severe rash on her arms & was having trouble breathing.
The employee told us that the carpet under her desk remained wet for a few days following the leak incident of a year ago

Particle counts were collected in thirty locations throughout the 10,000 SF building. Ambient readings and readings at air supplies were collected.
Particle counts were normal for the building in all areas except near the affected employee’s desk, averaging 1167 count in the 1.0 to 10.0- µ m classifications. Readings near the desk averaged 1483.

After slightly agitating the carpet under the employee’s desk, particle readings jumped over 300% from 1483 to 4619 in the 1.0 - 10.0 µ m classifications.

Lab analysis indicated an elevated presence of aspergillus/penicillium in a sample of the carpet and an elevated count of 1320 aspergillus/penicillium spores/m 3 in the total spore count collection from under the desk. An air culture indicated a count of 271 cfu/m 3 of penicillium.
The employee is allergic to penicillin and her doctor believes that her immune system had a reaction to the spores released from the carpet during vacuuming.
The carpet was replaced and the area cleaned and the employee has had no further issues.

Case Study #4: Three Crawl Spaces
Examines the relationship between room particulate counts in residences with crawl spaces with some areas of visible fungal contamination.
Question: is there a correlation between elevated airborne particle counts in an area with no visible contamination and an adjacent but hidden area with visible contamination such as in a crawl space?

Conclusion
Based on somewhat limited data, the opticle particle counter appears to provide the IAQ investigator who is assessing an apparently clean area with information that relates to fungal contamination in an adjacent but hidden contaminated area.

Data Set from 21 Locations
A collection of pre- and post-remedial readings from residential, office and medical buildings
Criteria for inclusion:
Our firm performed the assessments
The identical calibrated equipment was used for data collection
Lab analysis was performed by the same lab
Data is less than one year old

Conclusion
The opticle particle counter provides the IAQ investigator with a convenient means to gather a substantial amount of reliable, real-time data relating to air quality. It is a valuable addition to the IAQ investigator’s toolkit.
More research is needed, however, to determine how the data is to be interpreted.

Additional Research Areas What role does the environmental condition play? Dampness Barometric Pressure Building Pressurization Temperature

Selection of a Particle Counter
Define the intended use of the device - will you be assessing cleanrooms or ‘dirty’ areas (or both?)
Decide on the features you require - will you be storing large amounts of data, assessing for certain particle sizes, printing readings on site, or downloading data into a computer?
How easy is the unit to use? Can it survive a fall or extreme conditions? Does it have a touch-screen interface? Can it record temperature & humidity readings in addition to particle sizes and mass concentration?
You may want to try renting a unit prior to making a purchase so you don’t make a mistake (these devices start around $2000)

ISO 14664-1 Cleanroom Standards 293,000 29,300 2,930 293 29 5 µ m 8,320,000 35,200,000 ISO 9 832,000 3,520,000 ISO 8 83,200 352,000 ISO 7 8,320 35,200 102,000 237,000 1,000,000 ISO 6 832 3.520 10,020 23,700 100,000 ISO 5 83 352 1,020 2,370 10,000 ISO 4 8 35 102 237 1,000 ISO 3 4 10 24 100 ISO 2 2 10 ISO 1 1 µ m 0.5 µ m 0.3 µ m 0.2 µ m 0.1 µ m

Selected Resources
American Industrial Hygiene Association, Assessment, Remediation, and Post-Remediation Verification of Mold in Buildings (2004)
National Air Duct Cleaners Association, Assessment, Cleaning and Restoration of HVAC Systems (ACR 2006)
Hollace S. Bailey, Fungal Contamination: A Manual for Investigation, Remediation and Control (2005)
Particle Measuring Systems, Counting Efficiency and Resolution in Optical Particle Counters (2007)

Authors
Craig Whittaker , Ph.D., CIE
Environmental Solutions Group
Steven Armstrong , M.S., P.G.
Environmental Solutions Group

Thank you for attending!
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Whittaker Powerpoint June 08

by ESG Energy on Feb 07, 2010

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Whittaker Powerpoint June 08 — Presentation Transcript