INDOOR AIR QUALITY ASSESSMENT
Massachusetts Department of Public Health
Bureau of Environmental Health
Indoor Air Quality Program
Outline
•	IAQ background
•	General IAQ assessment 
–	Dates Visited
•	July 14, 2008
•	December 11, 2008 
•	January 21, 2009
•	April 22, 2009
•	Health Effects Discussion
•	Recommendations
•	Questions

Conditions that Influence Indoor Air Quality

•	Poor Design
•	Poor Maintenance
•	Occupant Induced

Conditions that Influence Indoor Air Quality
Poor Design
Examples: 
•	Inadequate or Nonexistent HVAC Systems
•	Poor Construction/Design
•	Right Design/Wrong Climate
•	Over-Designed/Multiple Moving Parts

1990s Repairs

•	Replacement of duct boards-taped ducts
•	Replacement of air handling units
•	Replacement of HVAC system chiller
•	Roof replaced
–	No slope
–	No additional roof drains

Environmental Measurements
Indoor Air Quality 
Ventilation
Parameter typically measured to ascertain ventilation equipment function:
•	 Carbon Dioxide Levels: 
≥ 800 ppm indicates inadequate ventilation
600-800 ppm acceptable air exchange
< 600 ppm is preferable in elementary schools 

Indoor Air Quality 
Ventilation

Carbon Dioxide Measurements

•	Above 800 ppm in 6 of 71* areas surveyed, indicating adequate ventilation in majority of the areas surveyed (December 11, 2008)

*    It is important to note that several classrooms had open windows and/or were empty/sparsely populated 

Indoor Air Quality 
Ventilation

Additional Parameter Typically Measured To Ascertain Ventilation Equipment Function:

•	  Temperature: 
Comfort Range: 70 o F to 78 o F 
•	  Relative Humidity:
Comfort Range: 40% to 60% 

Indoor Air Quality 
Ventilation
December 11, 2008

Temperature Measurements: 68o F to 74o F

Relative Humidity Measurements:  12% to 25%

Low Relative Humidity
Relative Humidity < 20 % 
•	is found frequently during the winter indoors in New England during cloudless, below- freezing weather conditions
•	dry eyes, mucous membranes, throat irritation
•	exacerbate preexisting skin rashes
•	leads to increased 
–	aerosolization of dusts
–	evaporation of VOCs
HVAC Equipment

Indoor Air Quality
Point Source Irritants
Point source pollution parameters:
•	Carbon monoxide
levels of fresh air introduced to a building should not exceed the NAAQS* level of 9 ppm in an eight-hour average. 

•	Airborne particles 
Levels for particulate matter with a diameter of 2.5 μm or less (PM2.5) should be maintained below the NAAQS* level of 35 μg/m3 over a 24-hour average 

*The NAAQS were adopted by reference in the BOCA National Mechanical Code of 1993, which is now an HVAC standard included in the Massachusetts State Building Code.

Carbon monoxide:
•	ND in all areas surveyed

Particulate Matter (PM2.5):
•	Outdoors/Background: 17 μg/m3 
•	7 - 15 μg/m3

Wall/Window Frame Temperature Analysis
•	Building occupants report temperature extremes

–	Building is unable to cool in the summer

–	Building in the winter is:
•	Too cold in classrooms on the exterior walls
•	Too warm in rooms in the core of the building
Surface Temperature Survey
 January 21, 2009 
•	Using a laser thermometer, the temperature of the following building components were measured inside the building:

–	Window frames
–	Exterior door frames (where present)
–	Exterior walls
–	Walls dividing classrooms
–	Hallway walls

Surface Temperature Survey
 January 21, 2009 
•	Assumption:  If properly insulated, temperatures of building components inside classrooms should be near the room air temperature.

•	Set point for the thermostat at the ACS is 68o F 

•	Therefore  the temperature of window frames, exterior door frames, exterior walls, walls dividing classrooms and hallway walls should be in a range of 63o F to 73o F (+/- 5o F)

Surface Temperature Survey Results
 January 21, 2009 
–	Window frames			 0oF to 103oF 

–	Exterior door frames		 0o F to 26o F 

–	Exterior walls			20o F to 63o F 		
–	Walls dividing classrooms	 35o F to 67o F 

–	Hallway walls			 37o F to 69o F 

Thermal Bridge
•	Thermal bridge is created when materials that are poor insulators come in contact, allowing heat to flow through the path created. 

•	Repeating thermal bridges - where bridges occur following a regular pattern, such that made by wall ties penetrating a cavity wall. 
Insulation
•	R Rating-A measure of the capacity of a material, such as insulation, to impede heat flow, with increasing values indicating a greater capacity 

•	The higher the R-value, the greater the insulating effectiveness. 
Thermal Bridge
•	If an object transverses the insulation (e.g., a steel bar), heat loss will occur, lowering temperature 

•	It is as if the insulation is not in place 

Repeating Thermal Bridges
Note Wire and Space in Wall
Windows are Single Pane with Non-insulated Window Frames

Understanding Dew Point
•	When warm, moist air passes over a cooler surface, condensation can form.  Condensation is the collection of moisture on a surface at or below the dew point.  

•	The dew point is the temperature that air must reach for saturation to occur.  If a building material/component has a temperature below the dew point, condensation will accumulate on that material.

•	Over time, condensation can collect and form water droplets.  
Understanding Dew Point
•	American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), if relative humidity exceeds 70%, mold growth may occur due to wetting of building materials

•	It is recommended that porous material be dried with fans and heating within 24 to 48 hours of becoming wet (US EPA, 2001, ACGIH, 1989)

•	If porous materials are not dried within this time frame, mold growth may occur

•	Water damaged porous materials cannot be adequately cleaned to remove mold growth
Calculation for Dew Point 
January 21, 2009
•	Temperature indoors 	68o F
•	Relative Humidity		46% outdoors
•	Dew Point			46o F

•	On this day, 41 windows were below the dew point 

•	Therefore, a major contribution to wood rot on sills is likely due to condensation, with periodic moistening by rainwater penetration
Microbial Growth
Conditions Needed to Grow Mold 

•	spores
•	nutrients
•	temperature >45o F
•	water (moisture)
–	Material should be dried within 24 - 48 hours of becoming moistened

Components of a Mold Colony That Can Be Allergenic

•	Mold*
•	Spores*
•	Mycotoxins
•	Mycelia Fragments
•	Mold Volatile Organic Compounds

* killed by fungicides/sporicides

Why Does Mold Growth Occur Indoors?
•	Water is either entering or failing to exit the building interior.
•	Materials that can support mold growth are stored/placed in an area that can become moistened for an extended period (> 24 hours). 
–	Example: storing books in a basement prone to condensation generation in the summer
•	condensation
 Materials Unlikely To Grow Mold With 
an Adequate Moisture Source
•	Cement
•	Cinderblock
•	Brick
•	Steel and other metal
•	Floor tiles
•	Hard Plastic

•	If mold appears, the mold growth medium is settled onto the surface of the material
•	Remediation recommendation = Cleaning of surface
Materials Likely to Grow Mold with 
an Adequate Moisture Source
•	carpet
•	ceiling tiles
•	drapery
•	gypsum wallboard
•	paper
•	books
•	particle board/plywood
•	cardboard
•	potting soil
•	fiberglass insulation
•	soft plastic
•	soft wood
•	Each material contains carbon, which serves as the food source for mold

•	Remediation recommendation = 
	Removal of the material if moistened for an extended period of time

Other Concerns

Rodent infestation
•	Rodents can be a source of disease and infestation can result in indoor air quality related symptoms due to materials in their wastes.  
•	Mouse urine and feces contain a protein that is a known sensitizer (US EPA, 1992).  

•	A sensitizer is a material that can produce symptoms (e.g. rhinitis and skin rashes) in sensitive individuals. 
Rodent infestation
•	A three-step approach is necessary to eliminate rodent infestation:

•	removal of the rodents

•	cleaning of waste products from the interior of the building
 
•	reduction/elimination of pathways/food sources that are attracting rodents such as toasters/toaster ovens in classrooms 

Rodent attractor
Paper mâché
•	Paper mâché paste is a liquid adhesive usually made using flour and water.

•	 It closely resembles wallpaper paste. It can be used as a paste for paper mâché projects and also decoupage, collage, and book binding. 

•	One classroom floor had substantial paper mâché residue on its floor

Rodent attractor
Bait Trap Inappropriately Placed
Noise in gymnasium
•	Reports concerning the noise in the gymnasium that is created by the HVAC system. 

•	Factors increasing noise in gymnasium
–	The AHU is hung from the ceiling of the gymnasium.
–	The AHU and its ductwork are not externally insulated.  
–	Ductwork does not appear to be internally insulated. 

•	In this configuration, the HVAC system ductwork amplifies noise from the AHU fan and motors.  Insulation on the ductwork would dampen the vibrations and reduce noise.
Health Concerns
Health Effects
Interview Results
•	All school personnel were offered opportunity to be interview by DPH staff.  15 agreed to be interviewed.
•	The predominant symptoms in this category were sinus congestion/infection and colds.  

Health Effects
Interview Results 
General Indoor Air Quality
•	variation in temperature (some individuals reported the building being too hot while others reported it being too cold)
•	variation in humidity (some individuals reported that the air is too dry while others reported that it is too moist)
•	water damage
•	poor ventilation
•	mold
•	pests
•	dust
•	general building deterioration

Health Effects 
Medical Record Reviews
•	Of the 15 employees interviewed, 5 consented to have their medical records reviewed and returned signed medical record release consent forms. 

•	Despite repeated requests, MDPH staff were not able to obtain one set of medical records for one individual.  

•	According to BEH’s physician, several of the IAQ conditions observed may contribute to eye or respiratory irritation; these include 
–	low levels of humidity,
–	presence of particulates and dusts
–	VOCs 
–	conditions conducive to attracting rodents
–	mold/moisture in areas prone to water damage

Health Effects 
Medical Record Reviews

•	The five cases reviewed show one commonality, rhinosinusitis (a condition involving inflammation in one or more of the paranasal sinuses) symptoms.

•	Typically, rhinosinusitis is the result of irritation, allergic reaction, or infection. 
Health Effects 
Discussion
•	The symptoms reported among participants of this health investigation are generally those most commonly experienced in buildings with less than optimal indoor air quality.  

•	The symptoms most frequently reported by individuals at the ACS were respiratory/irritant effects including allergies, headaches, sinus congestion or sore, hoarse or dry throat as well as headaches.  

•	The diagnosis of rhinosinusitis among the 5 individuals whose medical records were reviewed may be impacted by some conditions observed in the building

Recommendations
Short and Long-Term

Short-Term Recommendations
•	Remove/replace original, water-damaged wood sills from the base of all windows if wood is water stained or materially degrading.
•	Operate both supply and exhaust ventilation continuously during periods of school occupancy to maximize air exchange.  
•	Clean accumulated debris from FCU drip pans on a regular schedule.
•	Install filter racks on FCUs to hold filters in place.

MDPH IAQ Assessment Staff
Michael A. Feeney, R.Ph., J.D., C.H.O.
 Director, Indoor Air Quality Program
Bureau of Environmental Health
Massachusetts Department of Public Health
Tel. No. (617) 624-5757
Website: http://mass.gov/dph/indoor_air