Indoor Environmental Quality: Investigating the Problem

John W. Martyny, Ph.D., CIH

Causes of IAQ problems.

Outdoor pollution Indoor pollution Building material off-gassing Inadequate ventilation

How are IAQ Investigations Conducted?

IAQ Investigations

Building Characterization Symptom Survey Ventilation System Evaluation Source Identification Sampling Remediation

Building Characterization

Type and age of building Construction materials Primary uses Cleaning practices

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?

Construction Materials

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

Primary Uses

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

Cleaning Practices

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

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.

Questionnaire Topics

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

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

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

Unit Ventilators

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

and movement.

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

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.

Results of CO2 and ACH Sampling

CV VAV UV

GM of CO 2 715 ppm 666 ppm 573 ppm

CO 2 Range ( ppm) 390 - 957 318 – 1,763 295 – 1,450

% of Time > 1000 ppm 0% 11% 9%

Mean ACH 4.6 2.8 2.7

Range ACH 1.9 – 7.5 0.8 – 4.6 0.4 – 4.6

Particle Ratio Results

CV VAV UV

GM Ratio < 1 m 0.68 0.57 0.38

GM Ratio 1 – 3 m 1.39 3.08 5.47

GM Ratio > 3 m 3.20 4.80 14.76

Complaints by System Type

Type of Complaint More thanExpected

Less thanExpected

Too cold VAV CVIndividuals w/ complaints VAVEye Symptoms CV VAVHeadache Symptoms UV VAVNasal Symptoms UV VAV, CVThroat Symptoms UVDustiness Complaints UV CV

Source Identification

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

Sampling

Initial Site Assessment Secondary Sampling

Initial Site Assessment

HVAC system measurements: Carbon dioxide, air flow.

Ambient air measurements Carbon monoxide, carbon dioxide,

temperature, relative humidity.

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 - VOC’s, aldehydes, MVOC’s,

odors, particulates, etc. Bioaerosol Sampling Medical monitoring

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.

Tracer Gas Testing Methods Tracer gas characteristics. Tracer gas introduction methods:

Injection Constant Flow Duct injection Hood Testing

Concentration measurement methods GC Infrared

Tracer Gas Testing Methods (Cont)

Tracer gas introduction: Air Change Studies Contamination Studies Hood Studies

Results

What do results indicate? Limitations! Comparisons with carbon dioxide

methods for ventilation.

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.

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.

Where to conduct bioaerosol sampling.

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

Types of bioaerosol sampling.

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

Particulate Sampling

Methodology Mass collection Particle counters Condensation nuclei counters

Results - What do they mean???? Mass Mass/particle size Particle numbers Ratios

Particle Mass Conc., Cagewash, 2-29-2000

0.00E+00

1.00E-03

2.00E-03

3.00E-03

4.00E-03

5.00E-03

6.00E-03

7.00E-03

8.00E-03

9.00E-03

1.00E-02

9:17

:32

9:27

:32

9:37

:32

9:47

:32

9:57

:32

10:0

7:32

10:1

7:32

10:2

7:32

10:3

7:32

10:4

7:32

10:5

7:32

11:0

7:32

11:1

7:32

11:2

7:32

11:3

7:32

11:4

7:32

Time

Pa

rtic

le M

ass

Co

nc.

(m

g.m

3)

<0.523

0.523-2.5

2.5-10

10-20

Total Mass Conc, Powder-free Gloves, 8-30-2000

0.00E+00

1.00E-02

2.00E-02

3.00E-02

4.00E-02

5.00E-02

6.00E-02

7.00E-02

8.00E-02

9.00E-02

13:5

4:27

13:5

9:27

14:0

4:27

14:0

9:27

14:1

4:27

14:1

9:27

14:2

4:27

14:2

9:27

14:3

4:27

14:3

9:27

14:4

4:27

14:4

9:27

14:5

4:27

14:5

9:27

15:0

4:27

15:0

9:27

15:1

4:27

15:1

9:27

15:2

4:27

15:2

9:27

15:3

4:27

15:3

9:27

15:4

4:27

15:4

9:27

15:5

4:27

15:5

9:27

16:0

4:27

16:0

9:27

16:1

4:27

16:1

9:27

Time

Mas

s C

on

c. (

mg

/m3)

Total Conc

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.

Remediation Increase outside air Decrease outside air Control sources

Local exhaust ventilation Elimination Control devices

Contain construction or remodeling Isolate manufacturing areas

Factors confounding IAQ investigations

Ergonomic problems Smoking policies Comfort Complaints

Comfort Factors

Complaint Low School High SchoolCold 32% 73%Hot 21% 50%Stuffy 7% 52%Moldy 14% 10%Dusty 11% 23%Noisy 0% 19%Dry 11% 25%Crowded 0% 17%