MATERIALS SELECTION

FOR IMPROVING INDOOR AIR QUALITY IN SCHOOLS

September 1, 1997

William Maclay, AIA

William Maclay Architects and Planners

Warren, Vermont

MATERIALS SELECTION

FOR IMPROVING INDOOR AIR QUALITY IN SCHOOLS

William Maclay. AIA

William Maclay Architects & Planners

Warren, VT

· OVERVIEW

New construction products, materials, furnishings and equipment emit large quantities and varieties of chemicals into the air inside buildings, including schools. Research has indicated a connection between emissions from these materials and complaints from building occupants. Impacts on occupant health vary from mild irritation and discomfort to severe illness. While some building materials are suspected as irritants and human carcinogens, precise health effects are not known and fully quantified at this time. This places building users, designers, and owner’s in a risky situation where liability is not clearly defined. In addition to the uncertainty and lack of information in quantifying precise risks, interest groups, individuals, organizations and the media, have both under-emphasized and exaggerated potential indoor air quality (IAQ) risks and liability making it even more difficult to make prudent and responsible decisions.

What is needed is a common sense approach that can be used to minimize risks and to make responsible decisions in the design of schools. While answers are not obvious, it is possible to identify materials and products with a higher risk to indoor air quality. A policy of “prudent avoidance” of riskier products can be followed to limit the liability of building owners and designers. Potential risk and liability can be lessened if building owners, designers and managers incorporate the best available technology to reduce IAQ problems within reasonable cost parameters and document their efforts to address IAQ in building design, construction and maintenance.

Below is information intended to inform building designers, managers and owners of information about indoor air quality and procedures to reduce risk and liability. To offset risks of indoor air pollution caused by building materials in buildings, the toxicity of materials can be evaluated, less toxic materials can specified, toxic materials can be isolated or modified to lessen toxic impacts, and finally ventilation can be provided to dilute airborne pollutants. To be effective someone needs to an advocate to accomplish improve indoor air quality in schools. The following guidelines are intended to help a layperson or building professional to accomplish this goal. While some commitment to improving indoor air quality is necessary, construction or indoor air quality expertise is not required.

· CONTAMINATION SOURCES IN BUILDING MATERIALS

To evaluate the potential risk to indoor air quality of different building materials and products, the rate of emission of contaminants from the product or material needs to be determined. While detailed research is obviously preferable and can be provided by construction professionals, common sense and asking simple questions can help to avoid the worst potential problems. While our sense of smell is not a perfect scientific indicator, it does give some general relative indication of emissions from materials. The following product or material characteristics will affect the rate of emission of pollutants:

· The relative toxicity of the contaminant in the material or product: The more toxic the material is per amount of the material, the greater the potential hazard is.

· The quantity of the toxic material: The greater the quantity of the toxic material the greater the potential pollution is.

· The surface area of the material exposed to indoor air: The same quantity of material spread over a larger area is a greater concern than the same quantity with a smaller surface area.

· The adsorption rates of pollutants: Some materials such as carpet and acoustic ceiling tile adsorb pollutants over time.

· The temperature that will be maintained in the space: Typically hotter temperatures will increase emission levels from materials.

· The humidity levels in the space: Emission rates of materials may be affected by different levels of humidity. In addition, growth of harmful biological organisms may be encouraged with higher humidity levels. Different materials will support more or less biological growth. For instance, “soft surfaces” such as acoustic ceiling tile or fiberglass duct liners will support more biological growth than “hard surfaces” like tile or metal.

· Aging characteristics of materials: Pollutants will “outgas” over time. Some materials like paint outgas relatively quickly, while others like carpet or formaldehyde in particle board are much slower.

· Ventilation effects on materials: If ventilation is near to toxic emissions it will speed up emissions from materials. If emissions are removed from the building, ventilation can be a benefit. If a material tends to adsorb pollutants and is next to contaminated ventilation, increased ventilation can increase the adsorption of pollutants and be a liability.

To assess the risk to human health, the use of the space where materials are located should be considered. The following are additional factors to be considered evaluating materials:

· The location of materials in relation to occupants use: If the toxic material is located in a storage space that is removed from use by many people, then it is less of a potential health concern. Within a room, if the material is located closer to occupants, it is more of a concern than if it is farther away.

· The number of occupants exposed: If more people are potentially exposed then the material poses a greater threat to health.

· The duration of exposure: If people are near the toxic material for a short period of time then it is less of a concern then if they are near it for a longer time. For instance the materials in a classroom are more important to consider than materials in a corridor or gym, because of the differing lengths of time that there is potential exposure for building occupants.

· The age and size of the occupants: Children are smaller and weigh less than adults. The same level of pollutants in the air will have a significantly larger health impact the smaller the person is. Government standards for indoor air quality have been based on adults, and there are no standards based on the smaller size and body weight of younger children. Thus the potential for negative impacts from carpet is much greater for small children than adults, because they are shorter, they sit on the floor more frequently and they weigh much less.

· Interconnection with ventilation system: The ventilation system has interconnected impacts with the selection of materials. Generally, greater ventilation will remove pollutants and allow for improved IAQ. However, the use of “fleecy” materials next to ventilation, and particularly if combined with moisture problems, can cause the most serious health problems. Thus duct liners or spaces above dropped ceilings can make a dangerous breading ground and distribution system for biological organisms, particularly if moisture is added through leaks or other sources.

· MATERIALS SPECIFICATION FOR IMPROVING INDOOR AIR QUALITY

To minimize potential pollution from toxic materials, polluting materials should be eliminated where possible. Where this cannot be done for cost or other reasons, then contaminants should be isolated where feasible. Where contaminants are not eliminated or isolated, the final alternative is to ventilate remaining pollutants.

· Eliminate products and materials with contaminants

· Substitute with less toxic material: In many instances there are direct substitutes for polluting materials

· Substitute with different type of material: In other instances a different type of material with different characteristic and possible in a different construction assembly, may be a more appropriate solution.

· Isolate contaminants

· Remove outside building: Sometimes contaminant sources can be removed from the interior of the building.

· Remove from occupied space: In other instances contaminated materials can be avoided in occupied spaces, but be used in unoccupied spaces. If this strategy is used, it is important that the ventilation system of the building be designed to minimize migration of poorer quality air to occupied portions of the building. For instance, the ventilation system should exhaust air from an art room.

· Enclose in occupied space: Contaminates can be enclosed in closets or cabinetry.

· Enclose material to seal contaminant: Cabinets with particle board can be sealed to prevent outgassing.

· Provide additional ventilation for toxic materials: Ventilation system design is not covered in these recommendations, but materials and ventilation are interconnected.

· Directly exhaust contaminants: Where contaminants can not be eliminate, ventilation should be used to exhaust contaminants.

· Increase overall ventilation: Overall ventilation can be increased, although removal is preferable.

· Increase the outside air exchange rate: Most ventilation systems mix outside air and recirculated inside air. Increasing the percentage of outside air will improve the building air quality.

· Improve the distribution of air: Often there are parts of buildings with inadequate air provided. This is particularly problematic in older buildings where numerous renovations have converted storage rooms to office space or added new partitions.

· Maintain or improve filters: Often filters in mechanical systems are improperly specified and/or changed too infrequently.

The following are questions to ask in selecting materials:

· How much of the material or product will be used?

· What is the total surface area?

· How toxic is the material?

· Will the material/product adsorb pollutants?

· Will the material be located near where there is air movement and could this cause problems?

· Are the chemicals emitted from the product/material known as irritants, toxins, carcinogens or harmful to humans?

· What are the emissions rate for the product/material?

· Do emissions rates decline rapidly or slowly over time?

· Is the material/product located where it is likely to be in frequent occupant contact?

· Can the product/material be isolated from users?

· Can the product/material be sealed to isolate contaminants?

· Does the product/material require special ventilation?

· Is the material/product listed as hazardous or require special disposal?

· Can ventilation prior to occupancy reduce the pollution levels to safe levels?

· Are other materials available that are less toxic? At what cost?

· Is the product/material likely to encourage biological growth?

· Does the product/material require the use of toxic materials for proper maintenance?

· REVIEW OF COMMON BUILDING MATERIALS

The following is a review of some common building materials. This review neither claims to be exhaustive, nor to be an endorsement or non-endorsement of any product or material. The selection of materials is a process that should balance potential risks, user requirements, cost and other construction criteria. Review of manufacturer data and MSDS (Material Safety Data Sheets) sheets can provide useful information in comparing different materials. It would be nearly impossible to eliminate all toxic materials from schools and other buildings. However, it is possible to reduce the amount of toxic materials very significantly.

· Exterior materials: Generally exterior materials are less of a concern with regards to IAQ than indoor materials, with some exceptions. The typical exceptions include materials located near operable windows or ventilation system intakes, where pollutants from the outside can be carried inside by air movement. The pressurization of the building due to the mechanical system and/or wind will affect the potential for problems to occur.

· Roofing materials:

· Petroleum based waterproofing: The most significant potential for problems from the roof occur when reroofing occurs using petroleum based products when the building is occupied. These problems can usually be avoided easily by proper scheduling of roofing work.

· Foundation materials/products

· Insecticides: Insecticides are typically not a problem for building occupants, but can be either if they become airborne during building occupancy or if in the ground through groundwater pollution.

· Petroleum based waterproofing: This is typically not a problem for building occupants, unless being done while the building is occupied.

· Walls

· Wood preservatives: Preservatives are typically not a problem, but could be if the building is occupied.

· Paints: Exterior paints are typically only a problem when dealing with renovation projects where lead paint may be encountered and can cause problems through removal or through windows and door operation

· Sealants/caulking: Typically exterior sealants are not an IAQ problem.

· Insulation

· Biological growth: Insulation can become a significant health concern if combined with moisture causing growth of biological organisms.

· Interiors

· Subfloors and underlayments: Typically subfloor and underlayments made from plywood or particle board are relatively well sealed from interior spaces and use exterior grade phenol formaldehyde glues which generally are not considered a health risk rather than interior grade urea formaldehyde glues which are considered a greater risk.

· Sealants and caulks: Most sealants are petroleum based and contain volatile organic compounds (VOC’s). Most do outgas relatively quickly. Silicon is generally considered less toxic than most other sealants and caulks.

· Flooring and carpet adhesives: Waterbased adhesives are now available with much lower VOC’s.

· Flooring materials: “Hard” flooring materials such as stone, tile and sheet flooring are less of an indoor air quality concern than “soft” materials such as carpet. Vinyl flooring materials do outgas some at initial installation, but are a relatively minor concern. All carpet adsorbs pollutants and most carpet outgasses pollutants. The chemical 4PC (4-phenylcyclohexene) which is present in latex backed carpet has been identified as the most likely source of indoor air pollution from carpet. Even if carpet with fewer chemicals are installed, that does not eliminate adsorption of contaminants throughout the life of the carpet. Adsorption of contaminants in carpet is of equal or greater concern than toxic materials contained in new carpet. Carpet can be unrolled off site prior to installation to allow outgassing to occur outside the occupied space.

· Floor finishes: Water based floor finishes are now available with much lower VOC’s than oil based floor finishes. Once dry both finishes are relatively inert and are not significant pollutants.

· Ceiling materials: As with flooring materials “hard” materials are better than “soft” materials from an IAQ perspective. Ceiling tiles contain few pollutants, but do adsorb pollutants, but in less significant quantities than carpet. Metal and gyp board materials are not considered an IAQ concern.

· Wall coverings: Wall coverings are typically not an IAQ concern, but “softer” materials such as fabric could adsorb pollutants.

· Cabinetry and paneling: Cabinetry and paneling is typically made out of interior grade plywood or particle boards which contain urea formaldehyde which has been identified as a potential health risk. Interior grade particle boards are now manufactured without formaldehyde. Plywood with exterior grade glues can be used in some applications. Formaldehyde can also be sealed in with paint, urethane or plastic laminates.

· Paints and stains: Water based paint contain less VOC’s than oil based paints. Several major paint manufactures offer no VOC paints, although only in lighter colors. Other specialty manufacturers offer paints for chemically sensitive people. California has more stringent VOC regulations that can be used in specifying paints.

· Furnishings: Furnishings, including office partitioning systems, contain formaldehyde and other toxic materials. Major manufacturers can provide data on VOC’s and formaldehyde so that less toxic alternatives are selected. Furnishings and partitioning systems can be unwrapped and ventilated either on or off site prior to occupancy to allow as much out gassing to occur to minimize impacts on building users.

· Duct insulation: Fiberglass duct insulation, with fiberglass exposed to the air inside ducts, is a health risk and should be avoided.

· CONSTRAINTS IN SPECIFYING MATERIALS WITH IMPROVED INDOOR AIR QUALITY

Specification of products with improved indoor air quality characteristics, requires additional effort, over conventional specification. The following are some of the variables which should be addressed when specifying products with improved IAQ performance:

· Product performance: It cannot be assumed that simple substitutions can be made. Very often in specifying products with enhanced IAQ performance, characteristics of the more toxic materials are different from the less toxic substitute. These differences must be thoroughly researched to ensure that the building users requirements are met. Research should include review of MSDS sheets, detailed questioning of product engineers to find out how improved IAQ products may perform differently from typical products. For example, the use of less toxic water based adhesives for resilient flooring when used on slabs on grade may not perform properly if moisture migrates through the slab.

· Owner and user concerns: After the building designer has completed a thorough analysis of the product specifications, the designer should discuss the product performance with the building users and owner to make sure that owner and user requirements and concerns will be met.

· Contractor concerns: Contractors need to be clearly informed of any differences from standard construction practices. Unless notified specifically, they may assume they can substitute conventional products for products with improved IAQ performance. Or they may make assumptions about significantly increased difficulty in using products they are not familiar with and increase costs beyond what is reasonable to cover their concerns. The contractor also may discover valid concerns that limit the practicality of using products with enhanced IAQ. The owner and architect should assume their will be some additional time required to use products with improved IAQ.

· Availability: Availability may be an issue in incorporating products with improved IAQ. Again this is a reason why the designer should be careful in notifying the contractor about unusual products so that the contractor can properly schedule delivery.

· Cost: Providing improved IAQ typically will add to construction costs when compared with buildings with poorer IAQ. If costs are considered over the life of the building (lifecycle costing) then additional costs can be justified. This is particularly true when reduced risks of litigation and improved health and productivity of staff and students are included. To evaluate what IAQ measures to incorporate in the building design, it is useful to develop a list of potential IAQ improvements. During design estimated costs can be attached to each option. During bidding IAQ alternatives can also be broken out as alternates to accommodate the budget. While individual IAQ options may increase the construction cost by a significant percentage for use of an individual product or material, when evaluated within the overall budget the increases typically are insignificant. For instance non 4PC carpet will cost a $1-3 per yard more than comparable quality 4PC carpet. Formaldehyde free particle board may cost around 25% more than particle board with formaldehyde, but it is typically a very small portion of the overall budget. Sealing particle board adds minimal cost. No VOC paint adds little or no cost to comparable quality paint.

The recommendations indicated above may seem complicated and difficult. However with some common sense and commitment, it is possible for anyone to improve the IAQ of schools and other buildings through using the suggestions indicated above. What is necessary is the commitment of someone on the team responsible for getting a school built. This can be a school board member, a parent, a teacher, a staffperson, or someone on the architects or builders team. It can be as simple as hiring consultants who can provide the expertise necessary.

William Maclay is the principal of William Maclay Architects and Planners, which specializes in healthy building design, and is located in Warren, VT.