What is Indoor Air Quality?
Indoor air quality (IAQ) in I-BEAM refers to the quality of the air inside buildings as represented by concentrations of pollutants and thermal (temperature and relative humidity) conditions that affect the health, comfort and performance of occupants. Other factors affecting occupants, such as light and noise, are essential indoor environmental quality considerations but are not treated in I-BEAM as core elements of indoor air quality.
Why is IAQ Important to Building Managers?
Buildings exist to protect people from the elements and to otherwise support human activity. Buildings should not make people sick, cause them discomfort, or otherwise inhibit their ability to perform. How effectively building functions to support its occupants and how efficiently the building operates to keep costs manageable is a measure of the building's performance.
The growing proliferation of chemical pollutants in consumer and commercial products, the tendency toward tighter building envelopes and reduced ventilation to save energy, and pressures to defer maintenance and other building services to reduce costs have fostered indoor air quality problems in many buildings. Occupant complaints of odours, stale and stuffy air and symptoms of illness or discomfort breed undesirable conflicts between occupants or tenants and building managers. Lawsuits sometimes follow.
If indoor air quality is not well managed daily, remediation of ensuing problems and/or resolution in court can be extremely costly. So it helps to understand the causes and consequences of indoor air quality and to manage your building to avoid these problems.
Occupant Symptoms Associated with Poor Indoor Air Quality
Human responses to pollutants, climatic factors and other stressors such as noise and light are generally categorised according to the type and degree of reactions and the time frame in which they occur. Building managers should be usually familiar with these categories, leaving detailed knowledge to health and safety professionals.
Acute Effects: Acute effects are those that occur immediately (e.g., within 24 hours) after exposure. Chemicals released from building materials may cause headaches, or mould spores may result in itchy eyes and runny noses in sensitive individuals shortly after exposure. Generally, these effects are not long-lasting and disappear soon after exposure ends. However, exposure to some bio-contaminants (fungi, bacteria and viruses) resulting from moisture problems, poor maintenance or inadequate ventilation has been known to cause serious, sometimes life-threatening respiratory diseases which themselves can lead to chronic respiratory conditions.
Chronic Effects: Chronic effects are long-lasting responses to long term or frequently repeated exposures. Long term exposures to even low concentrations of some chemicals may induce chronic effects. Cancer is the most commonly associated long term health consequence of exposure to indoor air contaminants. For example, long term exposure to the following increases cancer risk:
- environmental tobacco smoke
- radon
- asbestos
- benzene
Discomfort: Discomfort is typically associated with climatic conditions, but building contaminants may also be implicated. People complain of being too hot or too cold or experience eye, nose or throat irritation because of low humidity. However, reported symptoms can be challenging to interpret. Complaints that the air is "too dry" may result from irritation from particles on the mucous membranes rather than low humidity, or "stuffy air" may mean that the temperature is too warm or there is lack of air movement, or "stale air" may mean that there is a mild but difficult to identify odour. These conditions may be unpleasant and cause discomfort among occupants, but there is usually no serious health implication involved. Absenteeism, work performance and employee morale, however, can be seriously affected when building managers fail to resolve these complaints.
Performance Effects: Significant measurable changes in people's ability to concentrate or perform mental or physical tasks have been shown to result from modest changes in temperature and relative humidity. Besides, recent studies suggest that similar effects are associated with indoor pollution due to lack of ventilation or the presence of pollution sources. Estimates of performance losses from poor indoor air quality for all buildings suggest a 2-4% loss on average. Future research should further document and quantify these effects.
Building Associated Illnesses
The rapid emergence of indoor air quality problems and
associated occupant complaints have led to terms which describe illnesses or
Effects particularly associated buildings. These include:
Sick Building Syndrome
Building-Related Illness
Multiple Chemical Sensitivity
Sick Building Syndrome (SBS): Sick Building Syndrome (SBS)
is a catch-all term that refers to a series of acute complaints for which there
is no apparent cause and where medical tests reveal no particular abnormalities.
The symptoms display when individuals are in the building but disappear when
they leave.
Complaints may include such symptoms as:
irritation of the eyes, nose and throat
headache
stuffy nose
mental fatigue
lethargy
skin irritation
These complaints are often accompanied by non-specific
Complaints such as the air are stuffy or stale. A single causative agent (e.g.,
contaminant) is seldom identified, and charges may be resolved when building
operational problems and/or occupant activities identified by investigators are
Corrected. Experience in resolving SBS complaints has led to many of the
suggestions for "good practice" found in I-BEAM.
The likely outcomes
of SBS problems which are not quickly resolved to include:
increased absenteeism
reduced work efficiency
deteriorating employee morale
Building-Related Illness (BRI): Building related illness
refers to a defined disease with a known causative agent resulting from
Exposure to the building air. While the causative agent can be chemical (e.g.,
Formaldehyde), it is often biological. Typical sources of organic
contaminants are:
humidification systems
cooling towers
drain pans or filters
other wet surfaces
water damaged building material
Symptoms may be specific or mimic symptoms commonly
Associated with the flu, including fever, chills and cough. Serious lung and
Respiratory conditions can occur. Common examples of building-related illness
include:
Legionnaires' disease
hypersensitivity pneumonitis
humidifier fever
Multiple Chemical Sensitivity (MCS): It is generally
recognised that some persons can be sensitive to particular agents at levels
Which do not have a noticeable effect in the general population? Besides,
it is recognized that certain chemicals can be sensitisers in that exposure to
the compound at high levels can result in sensitivity to that chemical at much
lower levels.
Some evidence suggests that a subset of the population may
be especially sensitive to low levels of a broad range of chemicals at levels
typical in today's home and working environments. This apparent condition has
come to be known as multiple chemical sensitivity (MCS).
Persons reported having MCS apparently have difficulty
being in most buildings. There is significant professional disagreement
concerning whether MCS actually exists and what the underlying mechanism might
be. Building managers may encounter occupants who have been diagnosed with MCS.
Resolution of complaints in such circumstances may or may not be possible with
the guidance provided in I-BEAM. Responsibility to accommodate such individuals
is subject to negotiation and may involve arrangements to work at home or in a
different location.
Factors Affecting Indoor Climate
The thermal environment (temperature, relative humidity and
airflow) are essential dimensions of indoor air quality for several reasons.
Many complaints of poor indoor air may be resolved by simply
altering the temperature or relative humidity
Thermally uncomfortable people will have a lower
tolerance to other building discomforts.
The rate at which chemicals are released from building
materials are usually higher at higher building temperatures.
Thus, if occupants are too warm, it is also likely that they
are being exposed to higher pollutant levels.
Indoor thermal conditions are controlled by the heating,
Ventilating, and air conditioning (HVAC) system. How well the thermal
the environment is managed depends on the design and operating parameters of The system, and on the heat gains and losses in the space being controlled. These
gains and losses are principally determined by:
indoor sources of heat
the heat gains from sunlight
the heat exchange through the thermal envelope
the outdoor conditions and outdoor air ventilation rate
Factors Affecting Indoor Air Pollution
Much of the building fabric, its furnishings and equipment,
Its occupants and their activities produce pollution. In a well functioning
the building, some of these pollutants will be directly exhausted to the outdoors
and some will be removed as outdoor air enters the building and replaces the
Air inside. The air outside may also contain contaminants which will be brought
Inside in this process. This air exchange is brought about by the mechanical
introduction of outdoor air (outdoor air ventilation rate), the automatic
the exhaust of indoor air and the air exchanged through the building envelope
(infiltration and exfiltration).
Pollutants inside can travel through the building as air
flows from areas of higher atmospheric pressure to regions of lower atmospheric
pressure. Some of these pathways are planned and deliberate to draw
pollutants away from occupants, but problems arise when unintended flows bring
contaminants into occupied areas. Besides, some pollutants may be removed
from the air through natural processes, as with the adsorption of chemicals by
surfaces or the settling of particles onto surfaces. Removal processes may also
be deliberately incorporated into the building systems. Air filtration devices,
for example, are commonly incorporated into building ventilation systems.
Thus, the factors most important to understanding indoor
pollution are:
indoor sources of pollution,
outdoor sources of pollution,
ventilation parameters,
airflow patterns and pressure relationships, and
air filtration systems.
Types of Pollutants
Common pollutants or pollutant classes of concern in commercial buildings along with conventional sources of these pollutants are provided below.
Table 1.1 Indoor Pollutants and Potential Sources
Pollutant or Pollutant Class | Potential Sources |
---|---|
Environmental Tobacco Smoke | Lighted cigarettes, cigars and pipes |
Combustion Contaminants | Furnaces, generators, gas or kerosene space heaters, tobacco products, outdoor air and vehicles |
Biological Contaminants | Wet or damp materials, cooling towers, humidifiers, cooling coils or drain pans, damp duct insulation or filters, condensation, re-entrained sanitary exhausts, bird droppings, cockroaches or rodents, dust mites on upholstered furniture or carpeting, or body odours. |
Volatile Organic Compounds (VOCs) | Paints, stains, varnishes, solvents, pesticides, adhesives, wood preservatives, waxes, polishes, cleansers, lubricants, sealants, dyes, air fresheners, fuels, plastics, copy machines, printers, tobacco products, perfumes, and dry cleaned clothing |
Formaldehyde | Particleboard, plywood, cabinetry, furniture and fabrics |
Soil gases (radon, sewer gas, VOCs, methane) | Soil and rock (radon), sewer drain leak, dry drain traps, leaking underground storage tanks, and landfills |
Pesticides | Termiticides, insecticides, rodenticides, fungicides, disinfectants and herbicides |
Particles and Fibers | Printing, paper handling, smoking and other combustion, outdoor sources, deterioration of materials, construction/renovation, vacuuming, and insulation |
Contaminant Sources
Indoor Sources
Identified below are some sources of contaminants commonly found in office buildings and offers some measures for maintaining control of these contaminants. Follow these measures to help maintain a healthy indoor environment.
Category/Common Sources
- Housekeeping and Maintenance (Includes) -
- cleansers
- waxes and polishes
- disinfectants
- air fresheners
- adhesives
- janitor's/storage closets
- wet mops
- drain cleaners
- vacuuming
- paints and coatings
- solvents
- pesticides
- lubricants
Tips for Mitigation and Control- Use low-emitting products
- Avoid aerosols and sprays.
- Dilute to proper strength (manufacturer's instructions)
- Do not overuse; use during unoccupied hours.
- Use proper protocol when diluting and mixing.
- Store properly with containers closed and lid tight
- Use exhaust ventilation for storage spaces (eliminate return air)
- Clean mops: store mop top-up to dry
- Avoid “air fresheners”—clean and exhaust instead.
- Use high-efficiency vacuum bags/filters
- Use Integrated Pest Management
- Occupant-Related Sources (Includes)
- Tobacco products
- Office equipment (e.g., Printers and copiers)
- cooking/microwave
- art supplies
- marking pens
- paper products
- personal products (e.g., perfume)
- tracked in dirt/pollen
Tips for Mitigation and Control- Smoking policy
- Use exhaust ventilation with pressure control for primary local sources.
- Low emitting art supplies/marking pens
- Avoid paper clutter
- Education material for occupants and staff
- Building Uses as Major Sources (Includes)
- print/photocopy shop
- dry cleaning
- science laboratory
- medical office
- hair/nail salon
- cafeteria
- pet store
Tips for Mitigation and Control- Use exhaust ventilation and pressure control
- Use exhaust hoods where appropriate; check hood airflows.
- Building-Related Sources (Includes)
- plywood/compressed wood
- construction adhesives
- asbestos products
- insulation
- wall/ floor coverings (vinyl/plastic)
- carpets/carpet adhesives
- wet building products
- transformers
- upholstered furniture
- renovation/remodeling
Tips for Mitigation and Control- Use low emitting products.
- Air out in the open/ventilated area before installing
- Increase ventilation rates during and after installing
- Keep material dry before enclosing.
- Use renovation guidelines
- HVAC system (Includes)
- contaminated filters
- contaminated duct lining
- dirty drain pans
- humidifiers
- lubricants
- refrigerants
- mechanical room
- maintenance activities
- combustion appliances (e.g., boilers/furnaces, DHW, generators and stoves)
Tips for Mitigation and Control- Perform HVAC preventive maintenance
- Use filter change protocol.
- Clean drain pans; proper slope and drainage
- Use potable water for steam humidification.
- Keep duct lining dry; move to line outside of duct if possible.
- Fix leaks/clean spills (see filter change protocol)
- Maintain spotless mechanical room (not a storage area)
- Avoid back drafting
- Check/maintain flues from the boiler to outside
- Keep combustion appliances properly tuned.
- Disallow unvented combustion appliances
- Perform polluting activities during unoccupied hours
- Moisture (Includes)
- mould
Tips for Mitigation and Control- Keep building dry
- Mould and Moisture Control Protocol
- Vehicles (Includes)
- Underground/attached garage
Tips for Mitigation and Control- Use exhaust ventilation
- Maintain garage under negative pressure relative to the building
- Check airflow patterns frequently
- Monitor CO
Outdoor Sources
Identified below are familiar sources of contaminants that are introduced from outside buildings. These contaminants frequently find their way inside through the building shell, openings, or other pathways to the inside.
- Ambient Outdoor Air (Includes)
- air quality in the general area
Tips for Mitigation and Control- Filtration or air cleaning of the intake air
- Vehicular Sources (Includes)
- local vehicular traffic
- vehicle idling areas
- loading dock
Tips for Mitigation and Control- Locate air intake away from the source
- Require engines shut off at loading dock
- Pressurise building/zone
- Add vestibules/sealed doors near the source.
- Commercial/Manufacturing Sources (Includes)
- laundry or dry cleaning
- restaurant
- photo-processing
- automotive shop/gas station
- paint shop
- electronics manufacturer/assembly
- various industrial operations
Tips for Mitigation and Control- Locate air intake away from the source
- Pressurise building relative to outdoors
- Consider air cleaning options for outdoor air intake.
- Use landscaping to block or redirect the flow of contaminants, but not too close to air intakes.
- Utilities/Public Works (Includes)
- utility power plant
- incinerator
- water treatment plant
Tips for Mitigation and Control- Locate air intake away from the source
- Pressurise building relative to outdoors
- Consider air cleaning options for outdoor air intake.
- Use landscaping to block or redirect the flow of contaminants, but not too close to air intakes.
- Agricultural (Includes)
- pesticide spraying
- processing or packing plants
- ponds
Tips for Mitigation and Control- Locate air intake away from the source
- Pressurise building relative to outdoors
- Consider air cleaning options for outdoor air intake.
- Use landscaping to block or redirect the flow of contaminants, but not too close to air intakes.
- Construction/Demolition
Tips for Mitigation and Control- Pressurise building
- Use walk-off mats
- Building Exhaust (Includes)
- bathrooms exhaust
- restaurant exhaust
- air handler relief vent
- exhaust from the major tenant (e.g., dry cleaner)
Tips for Mitigation and Control- Separate exhaust or relief from the air intake
- Pressurise building
- Water Sources (Includes)
- pools of water on the roof and cooling tower mist
Tips for Mitigation and Control- Proper roof drainage
- Separate air intake from the source of water
- Treat and maintain cooling tower water.
- Birds and Rodents (Includes)
- faecal contaminants and bird nesting
Tips for Mitigation and Control- Bird proof intake grills
- Consider vertical grills
- Use Integrated Pest Management
- Building Operations and Maintenance (Includes)
- trash and refuse area
- chemical/fertilisers/grounds keeping storage
- painting/roofing/sanding
Tips for Mitigation and Control- Separate source from the air intake
- Keep source area clean/lids on tight.
- Isolate storage area from occupied areas
- Ground Sources (Includes)
- soil gas
- sewer gas
- underground fuel storage tanks
Tips for Mitigation and Control- Depressurise soil
- Seal foundation and penetrations to foundation
- Keep air ducts away from ground sources.
Protocols for Managing Major Sources of Pollution in Buildings
Type of Protocol | Solution |
---|---|
Remodelling and Renovation |
|
Painting |
|
Pest Control Integrated Pest Management |
|
Shipping and Receiving |
|
Establish and Enforce a Smoking Policy | Environmental tobacco smoke (ETS) is a major indoor air contaminant. A smoking policy may take one of two forms:
(Partial policies such as allowing smoking only in private offices are not effective.)
|
Smoking Lounge Requirements | A designated smoking lounge must have the following features to be effective in containing ETS.
|
Managing Moisture and Mold (See also EPA's Mold Remediation Guidelines) | Mold thrives in the presence of water. The secret to controlling mould is to control moisture and relative humidity.
Keep all parts of the building dry that is not designed to be wet.
Thoroughly clean areas that are designed to be wet
Discard all material with signs of mould growth
|
Pollution Transport
Air Movement and Pressure: Contaminants reach occupant breathing-zones by travelling from the source to the occupant by various pathways. Usually, contaminants go with the flow of air.
Air moves from areas of high pressure to areas of low pressure. That is why controlling building air pressure is an integral part of controlling pollution and enhancing building IAQ performance.
Air movement should be from occupants, toward a source and out of the building rather than from the source to the occupants and out the building. Pressure differences will control the direction of air motion and the extent of occupant exposure.
Driving Forces: Driving forces change pressure relationships and create airflow. Conventional driving forces are identified in the table below.
Major Driving Force | Effect |
---|---|
Wind | Positive pressure is created on the windward side, causing infiltration, and negative influence on the leeward side, causing exfiltration, though wind direction can be varied due to surrounding structures. |
Stack Effect | When the air inside is warmer than outside, it rises, sometimes creating a column of rising air -- up stairwells, elevator shafts, vertical pipe chases etc. This buoyant force of the wind results in positive pressure on the higher floors and a negative influence on the lower levels and a neutral pressure plane somewhere between. |
HVAC/Fans | Fans are designed to push air in a directional flow and create positive pressure in front, and negative pressure behind the fan. |
Flues and Exhaust | Exhausting air from a building will reduce the building air pressure relative to the outdoors. Air exhausted will be replaced either through infiltration or through planned outdoor air intake vent. |
Elevators | The pumping action of a moving elevator can push air out of or draw air into the elevator shaft as it moves. |
Common Airflow Pathways
Contaminants travel along pathways - sometimes over great distances. Trails may lead from an indoor source to an indoor location or from an outside source to an indoor area.
The location experiencing a pollution problem may be close by, in the same or an adjacent area. Still, it may be a considerable distance from, and/or on a different floor from a contaminant source.
Knowledge of common pathways helps to track down the source and/or prevent contaminants from reaching building occupants.
Common Airflow Pathways for Pollutants
Common Pathway | Comment |
---|---|
Indoors | |
|
The stack effect brings about airflow by drawing air toward these chases on the lower floors and away from these chases on the higher levels, affecting the flow of contaminants. |
Receptacles, outlets, openings | Contaminants can quickly enter and exit building cavities and thereby move from space to space. |
Duct or plenum | Contaminants are commonly carried by the HVAC system throughout the occupied spaces. |
Duct or plenum leakage | Duct leakage accounts for significant unplanned airflow and energy loss in buildings. |
The flue or exhaust leakage | Leaks from sanitary exhausts or combustion flues can cause serious health problems. |
Room spaces | Air and contaminants move within a room or through doors and corridors to adjoining spaces. |
Outdoors to Indoors | |
Indoor air intake | Polluted outdoor air or the exhaust air can enter the building through the air intake |
Windows/doors, Cracks and crevices | A negatively pressurised building will draw air and outside pollutants into the building through any available opening. |
Substructures and slab penetrations | Radon and other soil gases and moisture-laden air or microbial contaminated air often travel through crawlspaces and other substructures into the building. |
Ventilation
Ventilation can be used to either exhaust pollutants from a fixed source, or dilute contaminants from all sources within a space.
Exhaust Ventilation: Ideally, exhaust airflow should be sufficient to draw pollutants from the source into the exhaust and away from occupants. The source should be located between the exhaust and the occupants. Rooms with significant sources should be under negative pressure relative to the surrounding spaces. Some sources, such as cooking stoves and laboratory benches, may require exhaust hoods. Also, see Exhaust Systems.
Dilution Ventilation: Contaminants from area sources such as people, building materials, office equipment, are diluted with outdoor air from natural or mechanical ventilation. Ventilation systems should be operated to provide sufficient outdoor air ventilation. Reducing outdoor air ventilation rates below required levels saves little energy and is not advisable. If capacity is available, outdoor air ventilation rates should meet applicable standards under all operating conditions. Problems with reduced outdoor air during part-load in specific VAV systems should be addressed.
Ventilation Measurements: Measurement instruments and techniques, which are generally available to building personnel, can be extremely useful in assessing the performance of the right ventilation system for both exhausting and diluting pollutants. Useful measuring tools include:
- Smoke tube to measure airflow
- Flow hood to measure air volume
- Velocity meter to measure air velocity
- Measuring carbon dioxide to estimate the percentage of outdoor air or to generally evaluate outdoor air ventilation
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