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Indoor Environmental Quality: Investigating the Problem

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John W. Martyny, Ph.D., CIH Causes of IAQ problems. Outdoor pollution Indoor pollution Building material off-gassing Inadequate ventilation How are IAQ Investigations ... – PowerPoint PPT presentation

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Title: Indoor Environmental Quality: Investigating the Problem


1
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?

6
IAQ Investigations
  • Building Characterization
  • Symptom Survey
  • Ventilation System Evaluation
  • Source Identification
  • Sampling
  • Remediation

7
Building Characterization
  • Type and age of building
  • Construction materials
  • Primary uses
  • Cleaning practices

8
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?

9
Construction Materials
  • Wood Construction vrs Metal
  • Fire proofing material
  • Crawl spaces
  • Carpeting and wall coverings

10
Primary Uses
  • Is a manufacturing area included?
  • What is the occupant density?
  • Computer usage.
  • Has the primary usage changed?

11
Cleaning Practices
  • Who cleans the building?
  • When is the building cleaned?
  • Cleaning product storage.
  • Cleaning product MSDS information?

12
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.

13
Questionnaire Topics
  • Demographic Questions
  • Comfort Questions
  • Medication Questions
  • Diagnosed Illness Questions
  • Symptom Questions
  • Air Quality Control Questions
  • Job Satisfaction Questions

14
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

33
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.

34
Results of CO2 and ACH Sampling
35
Particle Ratio Results
36
Complaints by System Type
37
Source Identification
  • Look for the following
  • Manufacturing areas
  • Print shops
  • Construction
  • Cleaning agents

38
Sampling
  • Initial Site Assessment
  • Secondary Sampling

39
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

43
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.

44
Tracer Gas Testing Methods
  • Tracer gas characteristics.
  • Tracer gas introduction methods
  • Injection
  • Constant Flow
  • Duct injection
  • Hood Testing
  • Concentration measurement methods
  • GC
  • Infrared

45
Tracer Gas Testing Methods (Cont)
  • Tracer gas introduction
  • Air Change Studies
  • Contamination Studies
  • Hood Studies

46
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.

49
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.

50
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
21
50
Stuffy
7
52
Moldy
14
10
Dusty
11
23
Noisy
0
19
Dry
11
25
Crowded
0
17
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