amudu: Everything you need to know about Indoor Air Quality in Buildings

Wednesday, November 13, 2019

Everything you need to know about Indoor Air Quality in Buildings

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.

Building Factors Affecting Indoor Air Quality

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	Use effective strategies for material selection and installation. Isolate construction activity from occupants.
Painting	Establish a protocol for painting and ensure that the contract is followed by both in-house personnel and by contractors. Use low VOC emission, fast-drying paints where feasible. Paint during unoccupied hours. Keep lids on paint containers when not in use. Ventilate the building with significant quantities of outside air during and after painting. Ensure a complete building flush before occupancy. Use more than normal outside air ventilation for some period after occupancy. Avoid spraying, when possible.
Pest Control Integrated Pest Management	Use or require the use of Integrated Pest Management by pest control contractors to minimise the use of pesticides when managing pests. Control dirt, moisture, clutter, foodstuff, harborage and building penetrations to minimise pests. Use baits and traps rather than pesticide sprays where possible. Avoid periodic pesticide application for “prevention” of pests. Use pesticides only where pests are located. Use pesticide formulated explicitly for the targeted pest. Apply pesticides only during unoccupied hours. Ventilate the building with significant quantities of outside air during and after applications. Ensure a complete building flush before occupancy. Use more than normal outside air ventilation for some period after occupancy. Notify occupants before occupation. If applying outside, keep away from the air intake.
Shipping and Receiving	Establish and enforce a program to prevent vehicle contaminants from entering the building. Do not allow idling of vehicles at the loading dock. Post signs and enforce the ban. Pressurise the receiving area relative to the outside to ensure that contaminants from the loading area do not enter the building. Use pressurised vestibules and airlocks if necessary. Periodically check the pressure relationships and compliance with the protocol. Notify delivery company supervisors of policy.
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: A smoke-free policy which does not allow smoking in any part of the building. A policy that restricts smoking to designated smoking lounges only. (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. The lounge should be fully enclosed. The lounge should be sealed off from the return air plenum. The lounge should have exhaust ventilation directly to the outside at 60cfm per occupant (using maximum occupancy). Transfer air from occupied spaces may be used as makeup air. The lounge should be maintained under negative pressure relative to the surrounding occupied spaces.
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 relative humidity below 60% (50%, if feasible, to control dust mites) Keep all parts of the building dry that is not designed to be wet. Adequately insulate exterior walls or ceilings to avoid condensation on cold surfaces. Insulate cold water pipes to avoid sweating Clean spills immediately. Thoroughly clean and dry liquid spills on porous surfaces such as carpet within 24 hours, or discard the material. Do not allow standing water in any location. Maintain proper water drainage around the perimeter of the building Provide sufficient exhaust in showers or kitchen areas producing steam Thoroughly clean areas that are designed to be wet Wash floors and walls often where water accumulates (e.g., showers) Clean drain often pans and insures a proper slope to keep water draining Ensure proper maintenance and treatment of cooling tower operations Discard all material with signs of mould growth Discard furniture, carpet, or similar porous material having a persistent musty odour. Discard furniture, carpet, or similar porous material that has been wet for more than 24 hours Discard ceiling tiles with visible water stains

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*
Stairwell Elevator shaft Vertical electrical or plumbing chases	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: