Indoor Environmental Quality: Investigating the Problem

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Indoor Environmental Quality Investigating the
Problem

• John W. Martyny, Ph.D., CIH

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Causes of IAQ problems.

• Outdoor pollution
• Indoor pollution
• Building material off-gassing
• Inadequate ventilation

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How are IAQ Investigations Conducted?

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IAQ Investigations

• Building Characterization
• Symptom Survey
• Ventilation System Evaluation
• Source Identification
• Sampling
• Remediation

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Building Characterization

• Type and age of building
• Construction materials
• Primary uses
• Cleaning practices

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Type and Age of Building

• Previous ventilation systems.
• What remodeling has taken place?
• What were the prior uses?
• Is asbestos a concern?
• Is mold a concern?

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Construction Materials

• Wood Construction vrs Metal
• Fire proofing material
• Crawl spaces
• Carpeting and wall coverings

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Primary Uses

• Is a manufacturing area included?
• What is the occupant density?
• Computer usage.
• Has the primary usage changed?

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Cleaning Practices

• Who cleans the building?
• When is the building cleaned?
• Cleaning product storage.
• Cleaning product MSDS information?

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Symptom Surveys

• Questionnaires vrs. Interviews
• The survey must
• Cover a majority of the staff.
• Be pre-tested.
• Eliminate bias.
• Not suggest answers.
• Not be a group effort.

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Questionnaire Topics

• Demographic Questions
• Comfort Questions
• Medication Questions
• Diagnosed Illness Questions
• Symptom Questions
• Air Quality Control Questions
• Job Satisfaction Questions

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Ventilation System Evaluation

• Visual inspection of System.
• Carbon dioxide (tracer gas) measurements.
• Look for the following
• Water infiltration
• Maintenance history
• General condition
• Use of local exhaust
• Placement of exhausts and intakes

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Ventilation System Characterization

• System Type
• Constant Volume
• Variable Air Volume
• Unit Ventilators
• Zones
• Single Zone
• Multi-Zone
• Reheat or No Reheat
• Ducts - Lined or Unlined

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Unit Ventilators

• Not actually an air handling system.
• Mount on outside wall.
• Provide some filtration, conditioning, and
  movement.

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Constant Volume Systems

• Provides a constant supply airflow rate to zones
  with similar thermal loads.
• Air temperature is controlled at the air handler
  or with reheat coils.
• Outside air is determined by
• Outside air temp.
• Damper settings
• Temperature demand

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Variable Air Volume Systems

• Provides a constant temperature air to the duct
  system.
• Air from the duct system is supplied to the zone
  to manage thermal load by the use of VAV boxes.
• Outside air is determined by
• Thermal demand of zone.
• Outside air temperature.
• VAV box and damper minimum settings.

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Results of CO2 and ACH Sampling
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Particle Ratio Results
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Complaints by System Type
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Source Identification

• Look for the following
• Manufacturing areas
• Print shops
• Construction
• Cleaning agents

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Sampling

• Initial Site Assessment
• Secondary Sampling

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Initial Site Assessment

• HVAC system measurements
• Carbon dioxide, air flow.
• Ambient air measurements
• Carbon monoxide, carbon dioxide, temperature,
  relative humidity.

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Secondary Sampling

• Should only be conducted when
• Specific information is to be collected
• Knowledgeable personnel are present
• HVAC measurements
• Tracer gas, duct velocities
• Ambient Air
• Chemicals - VOCs, aldehydes, MVOCs, odors,
  particulates, etc.
• Bioaerosol Sampling
• Medical monitoring

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Why conduct tracer gas testing?

• To determine air exchange rate for a building or
  area of a building.
• To determine fresh air distribution for a
  building or area of a building.
• To determine ventilation infiltration.
• To determine exhaust system effectiveness.

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Tracer Gas Testing Methods

• Tracer gas characteristics.
• Tracer gas introduction methods
• Injection
• Constant Flow
• Duct injection
• Hood Testing
• Concentration measurement methods
• GC
• Infrared

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Tracer Gas Testing Methods (Cont)

• Tracer gas introduction
• Air Change Studies
• Contamination Studies
• Hood Studies

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Results

• What do results indicate?
• Limitations!
• Comparisons with carbon dioxide methods for
  ventilation.

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Why conduct bioaerosol Sampling?

• Should only be done by experienced personnel and
  under limited conditions.
• To attempt to document the presence of a
  bioaerosol.
• To attempt to determine the type or species of a
  bioaerosol.
• To attempt to determine the cause of specific
  diagnosed diseases.
• To attempt to determine the effectiveness of a
  mitigation program.

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Why not to conduct bioaerosol sampling.

• To determine the presence or absence of a
  bioaerosol.
• To determine if an area is safe.
• To determine the cause of frequent colds, flu,
  rashes, etc..
• To show that mold from the carpet, etc. is
  entering the air.

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Where to conduct bioaerosol sampling.

• Choosing sampling areas.
• Choosing control areas.
• Choosing outside control areas.
• How many samples to collect?

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Types of bioaerosol sampling.

• Bulk Sampling
• Viable Sampling
• Non-viable sampling
• Dust sampling
• By-product sampling

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Particulate Sampling

• Methodology
• Mass collection
• Particle counters
• Condensation nuclei counters
• Results - What do they mean????
• Mass
• Mass/particle size
• Particle numbers
• Ratios

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Sampling complications

• Interpretation of results is difficult.
• Generally low probability of identifying a
  problem.
• High cost
• Grab samples may give non-typical results.
• Source identification may not be possible
• Source reduction will still need to be done.

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Remediation

• Increase outside air
• Decrease outside air
• Control sources
• Local exhaust ventilation
• Elimination
• Control devices
• Contain construction or remodeling
• Isolate manufacturing areas

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Factors confounding IAQ investigations

• Ergonomic problems
• Smoking policies
• Comfort Complaints

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Comfort Factors
Complaint
Low School
High School
Cold
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73
Hot
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Stuffy
7
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Moldy
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10
Dusty
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23
Noisy
0
19
Dry
11
25
Crowded
0
17