Michelle M. Schaper, Ph.D. 
I. Introduction and Examples
It is estimated that the average American spends 80-90% of each day indoors. Consider that this figure is likely to be even higher among some parts of the US population (e.g., infants, senior citizens, the infirm). Clearly, there is a large potential for inhalation exposures to occur in indoor environments. Thus, it is not surprising that the quality of the air that we breathe while indoors is a serious public health concern.
Example #1
A
government office building was renovated; the original carpet was removed and new
carpeting was installed. Shortly after the completion of the project, the
occupants returned to the building and immediately began to complain of eye
irritation, headache, and fatigue. The carpet had to be removed and replaced for
a second time.
Example #2
A small, family-operated insurance
office hired a nationally advertised company to clean their carpets. After the
cleaning was completed, the family began to experience eye irritation and skin
rashes (e.g., itching, reddening, swelling) for which they sought medical
treatment. The carpet and other office furnishings had to be removed and
replaced.
Example #3
A local high school had a wood shop that
was in need of renovation. The ceiling was cracked and insulation material was
falling from the ceiling to the floor. Students began to complain of eye
irritation and skin rashes (e.g., itching, reddening, swelling). Absenteeism rose
sharply and parents demanded action from the school principal. The ceiling was
sealed with a plastic covering until the end of the school year, after which a
new ceiling and ventilation system were installed.
II. Terminology and Acronyms
AIHA: American
Industrial Hygiene Association
ASHRAE: American Society for Heating and Air
Conditioning Engineers
BRI: Building Related Illness
EAQ: Environmental
Air Quality
EPA: Environmental Protection
Agency
ETS: Environmental Tobacco
Smoke
HEPA: High-Efficiency Particulate (filter)
HVAC: Heating, Ventilation, and
Air Conditioning
IAQ: Indoor Air Quality
IEAQ: Indoor Environmental Air
Quality
MCS: Multiple Chemical Sensitivity PM2.5: Particulate Matter (whose
size is 2.5mm, aeroequivalent diameter)
SBS: Sick Building Syndrome
VOC: Volatile Organic Compounds
III. Relevance of Indoor Air: Health Issues
A. Common complaints/symptoms (acute reactions): nonspecific
1. Chest tightness
2. Cough
3. Dryness of the eyes, nose, and/or throat
4. Fatigue (lethargy)
5. Headache
6. Irritation (burning) of the eyes, nose, and/or throat, "Office Eye Syndrome"
7. Light headedness
8. Loss of concentration
9. Nasal congestion
10. Nausea
11. Odor
12. Shortness of breath
13. Skin dryness and/or rashes
14. Wheezing
B. Sick Building Syndrome (SBS) and Building Related Illness (BRI)
Question: What
differentiates SBS from BRI?
Answer:
Primarily, identification of specific illness and its cause
Salient Features of SBS (adapted
from Tucker et al., 1992)
SBS
*Majority of occupants report symptoms
*Symptoms appear frequently in one building or one part
of it
*Five categories of symptoms cover major
complaints in building
-Sensory irritation
-Neurologic or general
health symptoms
-Skin
irritation
-Unspecific
hypersensitivity reactions
-Odor and taste problems
*Sensory irritation among most frequent symptoms
*No evident causality (e.g., exposure or susceptibility)
C. More serious health effects
1. Hypersensitivity Pneumonitis (HP) or
other allergic reactions
Examples: Bird
Fanciers Lung, Farmers Lung, Pigeon Breeders Disease
2. Legionnaires Disease
3. Aggravation/exacerbation of asthma or other respiratory disease
4. Aggravation/exacerbation of coronary heart disease (CHD)
5. Multiple Chemical Sensitivity (???)
IV. Components of Indoor Air Problems: Interaction Between
Buildings and People
A. HVAC
1. Temperature
ASHRAE temperature guidance:
seasonal dependence
Winter 68.5-75.5
°F
Summer 73.5-79.5 °F
a. Differential
between indoor and outdoor air
b. Within an
indoor area (e.g., room changes)
c. Use of
furnaces and space heaters
d. Use of air
conditioners and fans
e. Temporal patterns (e.g., day versus night)
2. Humidity
ASHRAE humidity guidance: ~40%
a. Moisture
levels
-Indoor
versus outdoor air
-Seasonal
differences
-Within
an indoor area (e.g., room changes)
b. Use of
humidifiers
3. Ventilation system
ASHRAE ventilation guide: 20 ft
3 /minute/person (non-smokers)
a. Air intake
and exhaust sites
b. Airflow in an indoor area -Air changes/hour
c. Duct and
fan condition (e.g., aging, cleanliness)
d. Filter
and/or scrubber efficiency (e.g., HEPA)
e. Building
design (e.g., positive versus negative pressure)
f. Temporal
patterns (e.g., day versus night)
B. Toxicants
1. Sources of contaminants in an indoor
area
a.
Outdoor versus indoor source
b. Building
and/or occupants
2. Aerosols
Figure 3. Identification of fungal species
in air samples collected during hospital renovation. (from Overberger et al.,
1995)
a. Particulates: asbestos, housedust, pesticides, PM2.5, vehicular
emissions
b. Bioaerosols: actinomycetes, bacteria, fungi Examples of fungi (as
seen in Figure 3): Penicillium, Aspergillus fumigatus, Aspergillus niger,
Cladosporium
3. Gases and vapors
a. Gases:
carbon dioxide, carbon monoxide, nitrogen dioxide, radon
b. Vapors:
acrolein, formaldehyde
"Off-gassing": often low molecular weight sensory irritants
i. Office/home furnishings
-Carpets and other
floor coverings
-Paints and other
wall coverings
-Furniture and
upholstery
-Glues and other
adhesives
ii. Office/home equipment -Photocopying
machines -Computer printers
iii. Automobiles/vehicles
4. Complex mixtures: ETS
5. Dose (concentration)-response
relationship
a. Individual variation and susceptibility: age, health status
b.
Immunosuppression
C. Personal activities
1. Housekeeping products and equipment
2. Tobacco use policy
3. Designated eating areas
4. Maintenance work
5. Hobbies/crafts
6. Personal care products and personal
hygiene
D. Neuropsychological issues
1. Compensation cases
2. Emotional problems/situations
3. Bandwagon appeal
4. Job stressors
V. Strategy for Assessing Indoor Air Problems
A.
Recognition
1. Visual inspection (e.g.,
notes, schematics)
2. Discussion with
occupants
3. Develop one or more
hypotheses
B. Evaluation
1. Questionnaire for occupants
2. Industrial hygiene
sampling/measurements
a. HVAC system
b. Source(s)
of toxicants
c. Pathway(s) for toxicants
d. Occupant
3. Modeling (e.g., EXPOSURE from EPA)
4. Comparison with published exposure
limits or guidelines
a. Threshold Limit Values-Time Weighted Averages (from the American
Conference of Governmental Industrial Hygienists, ACGIH)
Threshold Limit Values-Time Weighted Averages (TLVs-TWAs) refer to time-weighted average concentrations for a conventional 8-hour workday and a 40-hour workweek, to which it is believed that nearly all workers may be repeatedly exposed, day after day, without adverse health effects. Because of wide variation in individual susceptibility, however, a small percentage of workers may experience discomfort from some substances at concentrations at or below the threshold limit; a smaller percentage may be affected more seriously by aggravation of a preexisting condition or by development of an occupational illness..."
b. Sensory
Irritation (RD50s)
"
The RD50 is that concentration of a sensory
irritant that would produce intolerable burning of the eyes, nose, and
throat. Other common reactions include
lacrimation and coughing. It has been suggested that the RD50 be divided by 1,333
to obtain a exposure limit that is acceptable for indoor environments.
This has been called the Recommended Indoor Level or RIL (Nielsen et al., 1995).
Table 3.
Thus, there is some guidance available for individual chemicals that have been identified in room air. As an example, let us assume that your family is experiencing eye, nose, and throat irritation, particularly in several rooms. A contractor conducts air sampling and finds 0.1 ppm formaldehyde (> RIL, Table 3). These results may help to explain the complaints of irritation.
BUT, what should
be done if the concentration of formaldehyde is 0.0008 ppm (i.e., < RIL)?
Before deciding that this level does not represent an indoor air problem, be
sure to consider other possible sensory irritants in the room air. First, another
irritant may be responsible for observed eye, nose, and throat irritation. Second,
there may be a mixture of sensory irritants in the room air, where the concentration
of each chemical is below its respective RIL. The effects of the mixture may
be additive.
For mixtures having components that exert the same toxicological effect, Equation 1 has been given (ACGIH, 1998). It has been applied for nonreactive volatile organic compounds (NRVOC) by substituting the respective RIL for each Ti (Alarie et al., 1996).
This approach may be fine if
a) you have identified
each nonreactive sensory irritant in the room,
b) have determined its
concentration, and
c) have its RIL to use in
the denominator of Equation 1!
In some cases, you
will not have all of this information. Also, total volatile organic compounds
(TVOC), using toluene as a reference
chemical, may be reported in the analysis. The article by Alarie et al. (1996)
provides some suggestions for these situations.
C.
Control
1. Simple modifications (e.g.,
administrative): less costly
2. Complex
modifications (e.g., engineering): more costly
VI. Sampling
Equipment/Devices for Assessing Indoor Air Problems
(see Industrial Hygiene News)
A. HVAC
1.
Pitot tube (DP)
2. Anemometer or
velometer (air velocity)
3. Smoke tubes
or SF6 (direction of airflow)
4. Sling
psychrometer (temperature/humidity)
B. Toxicants
1. Direct-reading (portable) instruments
2. Gas/vapor adsorption techniques
3. Filters
4. Gas collecting bottles or bags
5. Indicator tubes
6. Viable samplers
C. Other
1.
Dosimeters, sound level meters
2. Radon
kits
3. Light meters
4. Vibration sensors
5. Workstation evaluations (e.g., chair
height, keypad location)
VII. Where to Get Help on Indoor Air
Problems
A. Internet (e.g., EPA)
http://www.aiha.org
http://www.iaqpubs.com
http://www.ashrae.org
http://www.epa.gov
http://www.osha.gov
B. Professional organizations (e.g., AIHA, ASHRAE)
C. Library (e.g., Journal of Air and Waste Management Association)
VII. References
Alarie, Y., Schaper, M., Nielsen, G.D., and Abraham, M.H. (1996). Estimating the sensory irritating potency of airborne nonreactive volatile organic chemicals and their mixtures. SAR and QSAR in Environ. Res. 5: 151-165.
American Conference of Governmental Industrial Hygienists (ACGIH) (1998). 1998 TLVs and BEIs: Threshold Limit Values for Chemical Substances and Physical Agents. Cincinnati, OH. pp.1-185.
Burge, H.A. and Hoyer, M.E. (1997). Chapter 19, Indoor Air Quality. In: The Occupational Environment -- Its Evaluation and Control. American Industrial Hygiene Association Press: Fairfax, VA. pp.390-421.
Jones, A.P. (1998). Asthma and domestic air quality. Soc. Sci. Med. 47(6): 755-764.
Kaufman, D.G. and Franz, C.M. (1993).Chapter 14, Air Resources. In: Biosphere 2000. Harper Collins College Publishers: NY. pp.268-274.
National Research Council (1991). Human Exposure Assessment for Airborne Pollutants: Advances and Opportunities. National Academy Press: Washington, DC. pp. 240-246.
Oliver, L.C. and Shackleton, B.W. (1998). The indoor air we breathe: a public health problem of the 90s. Public Health reports 113: 398-409.
Overberger, P.A., Wadowsky, R.M., and Schaper, M.M. (1995). Evaluation of airborne particulates and fungi during hospital renovation. Am. Ind. Hyg. Assoc. J. 56: 706-712.
Schaper, M. (1993). Development of a database for sensory irritants and its use in estblishing occupational exposure limits. Am. Ind. Hyg. Assoc. J. 54: 488-544.
Tucker, W.G., Leaderer, B.P., Molhave, L., Cain, W.S. (editors) (1992).Sources of Indoor Air Contaminants: Characterizing Emissions and Health Impacts. The New York Academy of Sciences: NY.
Wallace, L. (1996). Indoor particles: a review. J. Air Waste Manag. Assoc. 46: 98-126.
ESM 552 Environmental Chemistry Group Discussions for class. Michelle M. Schaper, Ph.D.
The first portion of our class will be spent in group discussions (covering parts of Chapters 9, 10, 11, and 12).
You may select one of the following three groups on which you will participate. Each group will discuss the assigned topics and will pick one student to serve as the spokesperson. At the close of the discussion, the spokesperson will summarize the key points to the entire class.
Several overheads may be prepared/used to assist in your summary. A period for questions will then follow which will be answered by the other, non-presenting members of the group.
Good luck!
Group I: Introduction to Air Pollution (use parts of Chapter 9)
A. What is the composition of
the air we normally breathe? Does it vary?
B. For air contaminants, what is
the difference between % vs. ppm vs. mg/m3?
How do the concentrations of air
pollutants compare with that of oxygen?
C. How do sun and water affect
the atmosphere?
D. What is
meant by the terms, greenhouse effect and global warming?
Why do we hear so
much about this issue in the news media? Is this a social issue?
E. What is meant by the term,
inversion? Where do inversions often occur (e.g., topography, city)?
Are there
health-related consequences of inversions?
F. What are some examples of
free radicals and how are they formed in the atmosphere?
Group II: Particles in the Atmosphere (use parts of Chapter 10)
A. What is the definition of ...an aerosol? ...a dust? ...a mist? ...particle?
Can you provide some
examples?
B. How are
aerosols generated?
C. What
is the size range for aerosols? At what size range are there often health
effects?
D. How do particles
behave/interact in the atmosphere?
E. What devices are used for
sampling particles?
F. Is it possible to control the
concentration of particles in the air?
Group III: Gas and Vapor Contaminants in the Air (use parts of Chapter 11,12)
A. How are the following
pollutants formed (i.e., sources): CO, NO2, SO2, formaldehyde and acrolein?
B. Are these air pollutants
reactive (e.g., water)?
C.
What is the definition of smog? Where and why does it occur?
D. What is acid rain? Why has
this issue been addressed by the news media?
E. What devices are used for
sampling such gases and vapors?
F. Is it possible to control the
concentration of gases and vapors released into the air?
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