#IAQ Articles

Repairs and Renovations

Planning

Renovation, redecorating, and remodelling activities can create indoor air problems by pro- ducing dust, odours, airborne bacteria, mould spores and chemical emissions. It is difficult to prevent IAQ problems if some building areas are undergoing renovation while adjoining areas continue normal operations. Advance planning, area isolation plans, worker access and other details must be identified and resolved before starting work.

8-2Materials used for repair and renovation should follow the same selection principles as materials selected for new construction. However, with repairs and renovations, emissions from materials and processes occur in enclosed spaces, usually managed by an operating HVAC system, and regular building occupants may be present in areas adjoining renovations.

Renovation is an opportunity to assess the previous selection of products in relation to IAQ and make choices that improve the work environment. As for new construction, materials exposed in a building interior should have surfaces that can be easily cleaned. Ensuring that these surfaces are also durable will reduce maintenance requirements as well as the IAQ impacts associated with replacement or refinishing. Particular attention should be paid to appropriate selection of flooring materials and surfaces used in restrooms.

Space Reorganization

Modern ventilation systems are custom-designed to suit space layout and occupancy. Layout changes may require changes to the HVAC system. For example, if two office spaces designed for 2 or 3 people are converted to a meeting room with a capacity for 10 or so people, the HVAC will need to be modified accordingly.

Please find more information on repairs and renovations, relating to IAQ in Module 3: http://iaqforum.ca/wp-content/uploads/2012/11/Mod3_Custodial.pdf

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IAQ Maintenance

Cleaning HVAC Systems

The HVAC system is a crucial aspect of indoor air quality. For detailed information about HVAC operation, refer to Module 5, Hygienic Operation of Air Handling Systems.

The HVAC system requires adequate preventive maintenance (PM) and timely repairs to operate cor- rectly and provide a comfortable environment with acceptable indoor air quality. HVAC system opera- tors must have an adequate understanding of the overall system design, its intended function, operational requirements, and its limitations. The PM program must be properly budgeted and implemented, not merely planned on paper.

13A well-implemented PM plan will improve the functioning of the mechanical systems and usually save money when evaluated on a life-cycle basis. However, in some buildings, because of budgetary constraints, lack of knowledge, or poor management, maintenance is delayed until breakdowns occur or complaints arise. Such practice often increases operational costs and could result in IAQ problems.

HVAC maintenance practices vary depending on the type of equipment, building types, and existing envelope measures, as well as building location, size, use pattern, and purpose. This makes it difficult to establish a single set of maintenance practices.

A clean mechanical room, free of tracked-in dirt and stored chemicals, is an important element in the prevention of indoor air quality problems. The state of the mechanical room is often an indicator of the care and commitment of the building operator. Airborne contaminants in the mechanical room can be drawn into ductwork through return air openings or unsealed seams in return ducts and be circulated throughout a building.

Ducts

Any duct cleaning should be scheduled during periods when the building is unoccupied to prevent occupant exposure to chemicals and loosened particles. The air handling unit should not be used during the cleaning or as an air movement device for the cleaning process. The National Air Duct Cleaning Association recommends that the system should be run to allow at least eight air changes in the occupied space after duct cleaning has been completed.

Negative air pressure that will draw pollutants to a vacuum collection system should be maintained at all times in the duct cleaning area to prevent migration of dust, dirt, and contaminants into occupied areas. Where possible, use vacuum equipment or fans
during cleaning and sanitizing to make sure that cleaning vapours are exhausted to the outside and do not enter the occupied space.

If it is determined that ductwork should be cleaned, careful attention must be given to protecting it and its interior surfaces (especially insulation and sound attenuating devices).

rsz_17When gaining access to sheet metal ducts for cleaning purposes, it is essential to seal access holes properly in order to maintain the integrity of the HVAC system. Use existing duct system openings where possible because it is difficult to repair the damage caused by cutting new access entries into the ductwork. Access doors are recommended if the system is to be cleaned periodically, and all access locations should be identified on the building’s mechanical plans.

Duct cleaning performed with high velocity airflow should include gentle, well-controlled brushing of duct surfaces or other methods to dislodge dust and other particles. Duct cleaning that relies only on a high velocity airflow through the ducts is not likely to achieve satisfactory results because the flow rate at the duct surface remains too low to remove many particles. Vacuum equipment should be used with care because high negative pressure can collapse ducts.

Since duct cleaning requires high volumes of air, seasonal timing is crucial. In cold or hot weather when high amounts of space conditioning are required, HEPA filtration and interior discharge of dust cleaning air will reduce make-up air requirements and energy costs.

Only HEPA filtered vacuuming equipment should be used if the vacuum collection unit is inside the occupied space or discharges to the space. Conventional vacuuming equipment may discharge extremely fine particulate matter back into the atmosphere, rather than collecting it. Duct cleaning equipment that draws dust and dirt into a collection unit outside the building is also available. People should not be allowed to remain in the immediate vicinity of these collection units.

If biocides are to be used, a written rationale and application plan should be prepared in advance. Select only approved products, use the products according to the manufacturer’s directions, and pay careful attention to the method of application.

Air duct after cleaning

5-3Careful cleaning and sanitizing of any parts of coils and drip pans can reduce microbiological pollutants. Prior to using sanitizers, deodorizers, or any cleansing agents, carefully read the directions on the pro- duct label. Once cleaned, these components should be thoroughly rinsed and dried to prevent exposure of building occupants to the cleaning chemicals.

Water-damaged or contaminated porous materials in the ductwork or other air handling system components should be removed and replaced. Even when such materials are thoroughly dried, there is no way to guarantee that all microbial growth has been eliminated.

After the duct system has been cleaned and restored to use, a preventive maintenance program will prevent the recurrence of problems. Such a program should include particular attention to the use and maintenance of adequate filters, control of moisture in the HVAC system, and periodic inspection and cleaning of HVAC system components.

The National Research Council (NRC) has conducted an evaluation of the effectiveness of duct cleaning. A report entitled “Testing Effectiveness of Duct Cleaning and Its Impact on Airborne Particles, Mold and Biocide Levels in Commercial Office Buildings” is available at by clicking here.

Filters
Filters that are not changed when required (based on their design loading and maximum allowable pressure drop) can become a bed for fungal growth, sometimes allowing particles or microorganisms to be distributed within the building. As filters are increasingly loaded, the fans use more energy to operate and move less air.

Clean air filters increase airflow through the system, resulting in improved system efficiency, indoor air- quality, and better occupant satisfaction. One of the simplest and most effective methods of increasing an HVAC system’s airflow and efficiency is to inspect and replace system air filters according to manufacturers’ recommendations.

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Cleaning Products and IAQ

Selection of Cleaning Products
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Cleaning is an essential activity. By its nature, cleaning involves removing physical contaminants and disinfecting, and therefore the use of chemicals for which we currently have limited knowledge about their effects on IAQ and on health. Given our incomplete knowledge, the goal is then to strive for a balance between effectiveness, effect on indoor air quality, labour and cost. There is no definitive list of cleaning products that maximize cleaning effectiveness while minimizing substances that can adversely affect indoor air quality. Table 3-2 (page 8) provides general information about attributes and ingredients. It is recopied from the U.S. Environmental Protection Agency (EPA) and is only an example of the type of information that is available. It should be used with discretion, as the terms “Preferred attributes” and “Preferred ingredients” are relative. Where custodial services are done under contract, the terms should specify the desired attributes of cleaning products.

Measuring/Diluting Concentrated Cleaning Products
Highly-concentrated cleaning products must be handled, stored and mixed (diluted) according to manufacturers’ directions. This can be achieved through a variety of methods including measuring cups, simple dispensing pumps and more complicated automatic dilution equipment. Follow these recommendations:

• Clearly post mixing instructions in janitors’ rooms;
• Use appropriate protective equipment when mixing concentrated cleaning products;
• Follow manufacturer’s dilution directions – do not under- or over-dilute concentrated cleaning products;
• Make sure secondary containers have appropriate label; and
• Never mix different cleaning products together.

Cleaning personnel should understand that adding extra concentrated cleaning product does not make it work better or faster. It wastes products and can also result in longer times to do a job (i.e., removing residues), slippery floors and surfaces, accumulations of chemical residues and other complications. The residue of most cleaning products attracts and retains dirt and may cause skin irritation and respiratory distress in some people.

Storage of Cleaning Products
The storage of cleaning products in well-designed and ventilated janitorial closets is an important aspect of an overall strategy to minimize IAQ impacts resulting from cleaning and maintenance. Provision of hot water taps and adequate mop sinks, proper dispensing systems for stock cleaning agents, moisture- resistant flooring materials, posted instructions for the preparation of cleaning agents, and protocols in well-located closets will assist in the delivery of improved cleaning services.
See references in section 9 for additional sources of information.

Janitorial Equipment
Vacuum cleaners should be equipped with a high-efficiency particulate air (HEPA) filtration system capable of trapping 99.97% (>0.3 μm) of all airborne particles collected by the vacuum.

Smoking Areas
Smoking areas should be located away from building entrances and away from ventilation intakes. It is important to provide clear signage for both designated smoking areas and areas where smoking is not permitted. Consult local bylaws for required distances. Information about smoking areas is available from:
Canadian Centre for Occupational Health and Safety (http://www.ccohs.ca/oshanswers/psychosocial/ ets_resolutions.html)

More information on cleaning products and IAQ can be found in Module 3.

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Carpet Care and IAQ

Carpet Care

3-5The strategy for minimizing the effect of carpet care on air quality begins with maintaining a high level of cleanliness at building entrances. Vacuum cleaning should:

  • Use equipment in good working order fitted with appropriate bags and/or filters (consider the use of HEPA filters).
  • Vacuum bags should be emptied or replaced as required to maintain adequate suction.
    Carpets can store undesirable dirt and microbials that can be activated when moisture is added, such aswhen extraction-cleaning is used. Effective cleaning and minimization of emissions can be achieved by:
  • Notifying occupants prior to large-scale extraction-cleaning activities and scheduling them for periods when a building is to be unoccupied such as before weekends and holidays. As more and more tenants are working during off-office hours, communication is important to determine times that are mutually acceptable.
  • Selecting appropriate cleaning solutions (see Section 5, Cleaning Products).
  • Minimizing the amount of cleaning solution used.
  • Using appropriate functioning equipment that will maximize the amount of water being extrac- ted from the carpet to minimize moisture and potential for mould, mildew and bacterial growth. Only in special situations should disinfectant be used after extraction-cleaning to prevent mould, mildew, and bacteria growth.
  • Increasing ventilation, opening windows if weather allows and using fans or dehumidifiers to dry carpets quickly so that carpets are completely dry within 24 hours.
  • Disposing of cleaning solutions properly.In general, extraction-cleaning should not be used for carpets that have an underlay due to the difficulty of removing water.

For more on custodial activities for indoor air quality go to: http://www.iaqforum.ca/wp-content/uploads/2012/11/Mod3_Custodial.pdf

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Cleaning Products for Ensuring Healthy IAQ

Cleaning Products

5.1. Selection of Cleaning Products6789942482_c9817d7d95

Cleaning is an essential activity. By its nature, cleaning involves removing physical contaminants and disinfecting, and therefore the use of chemicals for which we currently have limited knowledge about their effects on IAQ and on health. Given our incomplete knowledge, the goal is then to strive for a balance between effectiveness, effect on indoor air quality, labour and cost. There is no definitive list of cleaning products that maximize cleaning effectiveness while minimizing substances that can adversely affect indoor air quality. Table 3-2 (page 8) provides general information about attributes and ingredients. It is recopied from the U.S. Environmental Protection Agency (EPA) and is only an example of the type of information that is available. It should be used with discretion, as the terms “Preferred attributes” and “Preferred ingredients” are relative. Where custodial services are done under contract, the terms should specify the desired attributes of cleaning products.

5.2. Measuring/Diluting Concentrated Cleaning Products

Highly-concentrated cleaning products must be handled, stored and mixed (diluted) according to manufacturers’ directions. This can be achieved through a variety of methods including measuring cups, simple dispensing pumps and more complicated automatic dilution equipment. Follow these recommendations:

  • Clearly post mixing instructions in janitors’ rooms;
  • Use appropriate protective equipment when mixing concentrated cleaning products;
  • Follow manufacturer’s dilution directions – do not under- or over-dilute concentrated cleaning products;
  • Make sure secondary containers have appropriate label; and
  • Never mix different cleaning products together.Cleaning personnel should understand that adding extra concentrated cleaning product does not make it work better or faster. It wastes products and can also result in longer times to do a job (i.e., removing residues), slippery floors and surfaces, accumulations of chemical residues and other complications. The residue of most cleaning products attracts and retains dirt and may cause skin irritation and respiratory distress in some people.

5.3. Storage of Cleaning Products

The storage of cleaning products in well-designed and ventilated janitorial closets is an important aspect of an overall strategy to minimize IAQ impacts resulting from cleaning and maintenance. Provision of hot water taps and adequate mop sinks, proper dispensing systems for stock cleaning agents, moisture- resistant flooring materials, posted instructions for the preparation of cleaning agents, and protocols in well-located closets will assist in the delivery of improved cleaning services.

See references in section 9 for additional sources of information.

5.4. Janitorial Equipment

Vacuum cleaners should be equipped with a high-efficiency particulate air (HEPA) filtration system capable of trapping 99.97% (>0.3 μm) of all airborne particles collected by the vacuum.

For more information on cleaning products for ensuring healthy IAQ click here: http://www.iaqforum.ca/wp-content/uploads/2012/11/Mod3_Custodial.pdf

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Sources of Indoor Air Contaminants – IAQ

3-5Indoor air contaminants can originate within a building or be imported from outdoors. If contaminant sources are not controlled, IAQ problems can arise, even if the heating, ventilating and air-conditioning (HVAC) system is properly designed and well-maintained.

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has developed strategies and objectives for overall indoor air quality. The ASHRAE objectives that can be influenced by custodial activities, maintenance and renovation are:

  • Control moisture in building assemblies;
  • Limit entry of outdoor contaminants;
  • Control moisture and contaminants related to mechanical systems;
  • Limit contaminants from indoor sources;
  • Capture and exhaust contaminants from building equipment and activities; and
  • Reduce contaminant concentrations through ventilation, filtration, and air cleaning.

To learn more about Custodial Activities, Maintenance, Repair and Renovation in relation to indoor air quality (IAQ) visit:

 http://www.iaqforum.ca/wp-content/uploads/2012/11/Mod3_Custodial.pdf

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Best Management Practices for IAQ in Buildings

Industrial Air Conditioning Repair

Best management practices (BMPs) for indoor air quality are procedures implemented during the planning, construction and operation of buildings to reduce exposure and emission of pollutants. For example, many building operators have established BMPs for maintenance (e.g., air-handling unit filter changes) intended to ensure good IAQ.

BMPs may require VOC sampling in order to determine suitable occupancy or re-occupancy timeframes (e.g., during renovations when VOC levels may be elevated due to the introduction of new materials or prior to occupancy). The appropriate VOC sampling method depends on the source-pathway-receptor scenario for each case. The methods would generally include screening or semi-quantitative methods when quick results and monitoring of control measures are required; and quantitative results when occu- pancy criteria or certification is required.

BMPs have been issued by various authorities, primarily by federal, provincial and municipal agencies. Examples are listed in Table 2-1.

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What is acceptable air quality?

The guide modules we offer are based on the goal of providing acceptable air quality in buildings. The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) defines acceptable air quality as: “air in which there are no known contaminants at harmful concentrations as determined by cognizant authorities and with which a substantial majority (80% or more) of the people exposed do not express dissatisfaction.” However, air quality is a complicated topic and it is recognized that other definitions for acceptable indoor air quality may be desired or required.

A healthy indoor environment is one that contributes to productivity, comfort, and a sense of health and well-being. It is free from unacceptable levels of odours, dust and contaminants. Air circulation meets air change requirements without creating drafts. Temperature and humidity are appropriate for the activities in the building. Sanitation is maintained and water-related problems are quickly recognized and corrected. Failure to maintain acceptable indoor air quality can have consequences such as:

  • 8-2Increased health problems (e.g., coughing, eye irritation, headache, allergic reactions) and, in rare cases, more serious health problems (e.g., Legionnaire’s disease, carbon monoxide poiso- ning);
  • Absenteeism and loss of productivity;
  • Strained relations between landlords and tenants, and employers and employees;
  • Negative publicity that could threaten leasing opportunities or bring liability problems; and
  • Accelerated deterioration of furnishings and equipment.

Provision of good air quality requires conscientious effort by both building staff and occupants. The commitment to address IAQ problems starts with the building owner or facility manager – the person who has an overview of the organization, sets policy, and assigns staff responsibilities.

Although energy conservation is an important goal, it should not be achieved by actions that compromise air quality, such as reducing the amount of outdoor ventilation air without taking action to maintain the quality of the recirculated air. The modules of this guide indicate that acceptable air quality begins with good design and is continually supported by general maintenance, HVAC maintenance and ope- ration, attention to detail during repairs and renovations, and communication with, and education of, building occupants.

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Real Time Monitoring of VOCs

9Historical real-time screening techniques include several portable VOC sampling instruments that can give instant results for TVOCs as well as individual VOCs. Although their precision and detection limits are generally not as good as equivalent analytical laboratory instruments, portable instruments provide the advantage of real time measurements for projects requiring on-site decisions, rapid capture of tempo- ral variations, or involving large survey areas.

Colorimetric indicator tubes (e.g. Drager, Gastec)(portable)

Screening or semi-quantitative analysis may be obtained for a variety of VOCs by drawing a known volume of air through a colorimetric indicator tube. Samples are usually collected by use of a simple hand pump supplied by the manufacturer of the indicator tubes. The presence of analyte is indicated by a color change to reagent within a glass indicator tube. Indicator tubes are available for a variety of VOCs, often covering detection ranges of several orders of magnitude (ppm to %).

Colorimetric tubes are generally suitable for use in environmental conditions associated with indoor air, with restrictions on use identified by the manufacturer. Tubes are often only semi-specific with cross-interference common, manufacturer data identifying potential types and degree of cross- interference may be available.

Flame ionization detection (FID) (portable / stationary)

FID involves the detection of VOCs resulting from the combustion of hydrocarbons. As “stand- alone” equipment, FID is unable to differentiate between VOCs. Operating as a “carbon counter”, FID can function under most indoor environmental conditions and is not subject to significant cross- interference provided oxygen content is stable. FID may be combined with separation techniques (e.g., gas chromatography) and allows qualification of specific hydrocarbons based on retention time.

SONY DSCPhoto ionization detection (PID) (portable)

A PID uses an ultraviolet light to ionize a chemical. It can accurately measure gases at low ppmv or even ppb levels, however it cannot differentiate between chemicals. The electrically charged gas produces a current that is amplified and displayed as a concentration.

PID can be operated under most indoor environmental conditions, cross-interference is limited however different analytes provide different responses precluding accurate interpretation of results obtained from gases containing mixed analytes. Portable GC systems with PID detectors provide some separation of VOC for improved identification and quantification.

Sensor technology (portable)

Different sensor systems have been used to provide continuous on-site monitoring of VOCs. Most field sensors rely either on electrochemical, mass sensitive, or optical transducers. Typical sensiti- vities are in the ppm range but ranges may be extended by coupling sensors with a analyte enrich- ment method. Acceptable environmental conditions and susceptibility to cross-interference is sensor specific.

Metal oxide sensors (portable / stationary)

Metal oxide sensors measure the change in conductivity in the presence of oxidizing and reducing gases and are capable of providing real-time measurements.

Proton transfer reaction – mass spectrometer (PTR-MS) (stationary)

The detection principle of the PTR-MS is based on reactions to most of the common VOCs but
not with the components of clean air. PTR-MS has potential for on-site detection of VOCs with the advantages of rapid response and high sensitivity without sample pretreatment. PTR-MS can be ope- rated in most indoor environmental conditions.

Ion mobility spectrometry (IMS) (portable / stationary)

IMS is an analytical technique used to separate and identify ionized molecules in the gas phase based on their mobility in a carrier buffer gas. Related ionization MS techniques include desorption electrospray ionization (DESI) electrospray laser desorption ionization (ELDI), direct analysis in real time (DART) and atmospheric pressure solids analysis probe.

SIFT-MS – (stationary)

SIFT-MS is an analytical technique that uses chemical ionisation to analyse for VOCs in a whole air sample and can be used for real-time quantification. SIFT-MS is suitable for moist / humid sam- ples and is routinely utilized for analysis of human breath without need for sample conditioning.

Photo-acoustic spectroscopy (PAS) – (stationary)

A PAS system includes: a chamber to contain the gas sample, a light source, some means of modu- lating the light, a detector to measure the sound, and a method of processing the signal. The inten- sity of sound emitted by a sample depends on the nature and concentration of the substance and the intensity of the incident light (the photo-acoustic effect). Combining with FTIR allows identification of unknowns and their concentrations.

Advantages include infrequent calibration of the microphone; and linear response to gas concen- tration over a wide dynamic range (1 ppm to 103 ppm). The major disadvantage is the potential for interference between two gases of similar structure due to overlap of absorption bands. PAS is operable under typical indoor environmental conditions.

2005_sources_of_vocsInfra-red spectroscopy (IR) (portable / stationary)

The majority of hydrocarbons absorb energy when contacted by IR light, giving rise to a spectrum that can act as a ‘fingerprint’ that can be used to identify and quantify a contaminant. While IR analysis can provide instantaneous measurements, both contaminant identification and quantification may be subject to interference should air contain a mixture of contaminants.

An advantage of IR is the system stability allowing consistent results to be obtained over exten- ded periods with minimal quality assurance checks. Water vapour can impact IR analysers; sample conditioning is therefore required for analysis of high humidity samples.

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When to sample for VOCs

Sampling for VOCs should only be done after source elimination has been considered as a first step. If this is not possible, or too expensive, sampling could then be considered. The source-pathway-receptor relationship will have characteristics that will influence the sampling method and duration. Table 2-5 shows how VOC sampling can be tailored to suit various complaint patterns.

If the timing of a source is well known it may be used to define the source-pathway-receptor relationship and possibly eliminate or reduce the amount of VOC sampling required. For example, if odour or health complaints can be correlated with building conditions, occupant/neighboring activities, weather, or ventilation system status, then it may be possible to determine the source or pathway, and mitigate the problem without sampling or to adjust the sampling program.

The duration of sampling should provide data that it is representative and meaningful. How the data will be interpreted should be considered. Timing factors may also be defined by legislation such as determining short-term exposure or time weighted average exposure for workers. Where timing is not defined by legislation, occupants should be interviewed or asked to complete a questionnaire to gain an understanding of when exposure may be occurring. It is important to note that complainants may not always be objective when providing information.

When to sample for VOCs

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To learn more about VOC sampling methods go to our downloadable module: http://iaqforum.ca/wp-content/uploads/2012/11/Mod2_VOC.pdf

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