Word on the Street    

Florida Mold Bill Accepts IAQA Certification

IAQ in Homes- Why Ventilation is Necessary in Our Residences

MOLD, IAQ FIRE UP STATEHOUSES 

By BJ Spanos

The importance of providing good indoor air quality for public health and business is very apparent around a number of state legislatures this year. Presently, there are some 60 pieces of indoor air quality-related legislation being considered by 27 state legislatures. These bills can be grouped into the following three categories: mold and mold remediation (23 bills), schools (22) and public buildings (15).

Connecticut leads the pack with 10 bills, nine of which target school IAQ. The Texas state legislature is considering seven bills, mostly focused on mold and mold remediation. The following is an overview of this pending legislation. Subsequent updates will highlight specific bills and provide updates on significant actions.

Mold, Mold Remediation
Seventeen states are working on mold-related legislation, covering a wide range of issues, including the licensing of mold investigators and remediators, studies of mold and associated health impacts, insurance and real estate, guidelines and building codes, and the regulatory oversight and funding associated with public education.

Licensing of mold investigators and remediators: Two Texas bills seek to establish a licensing system and requirements for those who investigate and remediate mold problems. Texas Senate Bill 129 exempts certified industrial hygienists from the licensing requirements. Two other states (Florida and Louisiana) also exempt CIHs from their respective bills. A separate Florida bill (SB 2746) would establish a registration process for mold-related activities, set training requirements and charge a registration fee up to $600. This bill also specifies that individuals meeting the Indoor Air Quality Association’s education program or equivalent would be eligible for certification.

Studies of mold and health impacts. Six states (Alabama, Massachusetts, Illinois, Florida, Connecticut and Texas) have proposed legislation that would authorize studies of the mold issue and potential health impacts. Resolutions in four states (Indiana, Mississippi, Virginia and Nevada) target developing permissible exposure limits (PELs) for mold in indoor environments.

Insurance and real estate: Because mold in residences remains such a big issue in Texas, House Bill (HB) 3990 would require insurers to investigate all claims of mold damage under residential property insurance policies. Nevada is proposing to require insurers offering property insurance to obtain a disclosure statement of coverage for the control of mold.

A Louisiana resolution would require realtors to distribute an information pamphlet, prescribed by the state’s real estate commission, and also provides that if realtors deliver the pamphlet to the buyer, they are not required to provide any additional mold information. New York Assembly Bill (AB) 7221 would require the disclosure of indoor mold history upon the sale of residential property. Washington proposes to require landlords to provide tenants, at the time of lease, with information about the potential health hazards associated with exposure to mold and how they can control mold growth in their residences.

Guidelines and building codes. Another Texas bill would establish a building code advisory committee to advise and recommend building specifications and maintenance related to the use of mold, fire and water-resistant materials in residential building and repairs and related insurance issues. In a joint resolution, Tennessee’s Commissioner of Education would be authorized to establish guidelines regarding mold abatement in public schools and to create a task force to aid in developing these guidelines. Connecticut also is interested in developing protocols for assessing and addressing mold infestation in schools. New York (AB 7221) is proposing to authorize the state’s commissioner of health to promulgate rules and standards for the remediation and prevention of indoor mold. Virginia has a similar bill focused on occupational buildings.
Public education, regulatory oversight and funding. Pennsylvania is seeking to provide funding for a public education program about mold. Idaho would like to create the Idaho Heating, Ventilation and Air Conditioning Board to consolidate state resources and oversee the ventilation and air-conditioning industries, including problems associated with mold. Minnesota State Funding Bill 752 would allow the state’s health and safety revenue to be expended on mold abatement and IAQ improvements.

IAQ In Schools
Eleven states are addressing schools IAQ in this year’s legislative sessions. As noted, Connecticut has nine bills under consideration. Most of the proposed legislation is focused on developing standards and guidelines for school IAQ and inspecting schools to ensure good IAQ for students, teachers and staff. The specific issues address include:

• standards and guidelines
• IAQ management plans and inspections
• training, increasing awareness and IAQ Tools for Schools
• funding and reimbursement incentives
• HVAC systems
• property taxes
• sustainability

Standards and guidelines: As noted, the majority of proposed legislation is focused in this area, with Connecticut the most active state. Proposed legislation in Connecticut seeks to establish IAQ standards for schools, provide guidance to school districts for improving school IAQ, and require that school building projects incorporate IAQ standards in building design, including remediation plans to improve IAQ. A bill working its way through the Maryland legislature would mandate the creation and distribution of an IAQ standards guide to the state’s school districts.

Rhode Island SB 440 would require that state’s Department of Health set IAQ standards for the level of radon, bioaerosols, chemical compounds, volatile organic compounds, pesticide usage, the degree of pest infestation, the removal of hazardous substances, ventilation systems, plumbing and building structure for schools. And, a joint resolution in Texas (SB 242 and HB 473) would set in motion the establishment of mandatory guidelines for IAQ in public school building projects.

IAQ management plans and inspections: The Connecticut legislature also is considering proposed legislation to require biennial IAQ inspections for all school buildings. Connecticut HB 6426 specifies that these inspections should include evaluating the level of radon, bioaerosols, chemical compounds, volatile organic compounds, pesticide usages, the degree of pest infestation, and others. The bill would also require that all new school building projects complete IAQ inspections prior to approval.

A proposed Maryland bill would like to require each county board of education to develop a system to monitor school IAQ, as would a joint resolution in Texas (SB 242 and HB 473). Texas’ bills also specify that the inspections include evaluating the adequacy of ventilation and the presence of carbon monoxide, volatile organic compounds, formaldehyde, particulate matter, carbon dioxide and mold. In addition, Rhode Island is looking to require annual school IAQ inspections for all school buildings

The proposed legislation in Missouri would authorize that state’s Department of Health and Senior Services to investigate complaints regarding school IAQ made by public employees, and New Hampshire’s joint resolutions (SB 167 and HB 267) would require monitoring of school IAQ and investigating any complaints.

Training, increasing awareness and IAQ Tools For Schools program: Two Connecticut bills focus on ensuring school employees and teachers are well versed in school IAQ. HB 5636 would require the Commissioner of Public Health to annually conduct environmental health training workshops for certain school employees, based on the state’s Indoor Air Quality Tools for Schools publications. House Bill 6503 creates IAQ committees in each school to increase staff awareness of IAQ issues. A bill in the California state legislature would affirm that poor indoor air quality in schools exacerbates asthma symptoms, and would urge California school districts to implement the Indoor Air Quality Tools for Schools Program.

Funding and reimbursement incentives: Two Connecticut bills seek to provide funding through a public school building project grant program to improve indoor air quality in schools. And, one bill would allow the cost of fixing mold and other IAQ problems to be eligible for reimbursement from the state’s school construction program.

HVAC systems: Three pieces of proposed legislation being considered by New York focus on school buildings’ HVAC systems. One bill would require that all new school building projects or school remodeling be evaluated for quality of the air conditioning system’s design, and a joint resolution would require that all new child care facilities have HVAC systems.

Property taxes: To help pay for correcting safety code violations for indoor air quality, or for mold abatement and prevention, a proposed bill in Nebraska would allow that state’s school districts to levy a property tax for that purpose.

Sustainability: An energy conservation bill in Iowa recommends using IAQ systems that avoid the use of polluting chemicals as a way to promote healthier and environmentally sustainable classrooms.

IAQ In Public Buildings
Seven states have pending legislation focused on improving indoor air quality in public buildings, with Massachusetts having the most bills in the works. The issues these bills address include:

• tax incentives
• building ventilation rates
• building codes
• guidelines and standards
• investigation of IAQ complaints
• funding and state resources

Tax incentives: Massachusetts would like to encourage environmentally friendly buildings by proposing a Green Building Income Tax Credit/Incentive Program. Among the requirements to qualify for a tax credit are smoking restrictions, specific ventilation specifications, fresh air intake requirements and inspections by a licensed professional engineer or industrial hygienist.

Building ventilation rates: Massachusetts HB 452 would require mechanical ventilation systems in public buildings be maintained and operated to provide the appropriate outdoor air supply rate and that these systems will be operated continuously during working hours. New York’s resolution would require that, prior to approval, hospital construction plans must include proper ventilation design to provide “healthful” indoor air quality.

Building codes: As a part of Massachusetts’ overall effort to improve IAQ in public buildings, the state’s legislature proposes to grant the state’s Department of Labor and Industries authority to apply the ventilation codes, or more stringent codes and standards as appropriate, to ensure adequate IAQ during normal working hours in buildings occupied by state employees.

Guidelines and standards: New Mexico and Oregon’s resolutions would establish air quality standards for air contaminants. Oregon’s joint resolutions (SB 412 and HB 2708) focus on specific indoor air pollutants, including particulate matter, aldehydes, radon, carbon monoxide, carbon dioxide, ozone and water vapor. A New York bill proposes that building owners be required to develop and maintain an indoor environmental plan, investigate complaints and provide a written response. The bill also directs the state’s Department of Health to adopt standards of ventilation of new and existing buildings and to develop model courses in the operation and maintenance of HVAC systems.

Inspections of state buildings: Both Indiana and Texas have bills in the works to authorize IAQ inspections of all state buildings or buildings that house state employees.
Funding and state resources: Maryland SB 592 would establish the Office of Indoor Air Quality in the Department of the Environment. The office would be charged with enforcing the state’s IAQ regulations. This bill also creates the IAQ Advisory Council, which would work with the IAQ Office to monitor regulatory compliance in public and private office buildings of more than 2,500 sq. ft. of floor space. (N.B.: This bill was withdrawn on March 17.)

For More Information
State and Local Governments. A Library of Congress Internet Resource Page. http://lcweb.loc.gov/global/state/stategov.html
This article was produced in cooperation with Aerias LLC, a comprehensive online resource dedicated to promoting better human health and better business through indoor air quality awareness. Visit Aerias at www.aerias.org. Information presented in this update was derived from the Indoor Air Quality Association’s online Legislative Matrix. Visit www.iaqa.org for membership information and access.

Word on the Street

• Voices: “This [mold] can get out of control fast for a consumer. I was swimming in a pool filled with sharks and I didn’t know what was being talked about.”
  —Erin Brockovich-Ellis speaking about the mold contamination in her own home
  at last month’s Consumer IAQ Forum in Anaheim, Calif.
      
• Three Grand: The number of mold remediators certified by the Indoor Air Quality Association surpassed 3,000 in late March. The 3,000th CMR was Paul Campbell, of Pittsburgh-based Insurance Restoration Services.
     
  Director of Certification Farzana Shakir noted the growth of the CMR program over the past year, commenting, “When we crossed the threshold of 1,000 just before March 2002, we expected the number to double by the end of the year. Certifying dozens of applicants each week, we were ahead of schedule, and we’ve now tripled that original number only a few months into 2003.”
    
• Waiting to Exhale: An astoundingly high percentage of school-age children living in New York City’s Harlem area were found to have asthma. The 25 percent rate of incidence found in a yet-unpublished Columbia University study may even mark the first time the rate exceeded 20 percent, several asthma researchers commented in an April 19 article in the New York Times.
    
  The article, by Richard Pérez-Peña, goes on to speculate that environmental factors present in poor, urban areas may contribute to the widespread incidence of asthma experienced in those areas. It listed some of the more serious factors thought to contribute to asthma – particles in the exhaust of diesel fuel emitted by buses and trucks, cigarette smoke, fungi, dust mites, the feces of cockroaches – and stated that these are “most prevalent in poor communities” according to studies.
    
• Standards Gripes: Four members of the Association of Specialists in Cleaning and Restoration sent a letter to their fellow members, arguing that the direction the Institute of Inspection, Cleaning and Restoration Certification is taking on its forthcoming mold remediation standard is flawed. Pete Consigli, Cliff Zlotnick, Dennis Jensen and Brian Spiegel urged ASCR members who are IICRC certified to lobby industry officials to adopt a “state of the practice” based standard rather than one that is based on the “state of the art.” 
    
  The four say a state of the practice based standard is needed, “that is reflective of a practical, common sense application in the field.” According to an attorney familiar with the project, a state of the art standard would be based on best practices, not the state of the practice. Confused? We are too.
    
• Heeeeeere’s Money: Entertainer Ed McMahon has settled with all the defendants named in the April 2002 lawsuit he filed over mold that thrived in his 8,000-square-foot mansion. The final settlement, a $230,000 agreement with Controlled Environmental Solutions, was reached in April during the final full week before McMahon’s case was set to go to trial. The former Tonight Show announcer had claimed that the Stachybotrys chartarum had made his wife and himself sick and caused a fatal respiratory illness in their dog.
  
• Oregon’s Healthy Schools: A task force representing school administrators, school boards, teachers, health professionals and others released a report last month highlighting opportunities to better protect students’ from environmental health hazards in Oregon schools. The Healthy Schools for Healthy Kids report recommends more than 50 strategies to reduce exposures to environmental health threats in and around Oregon schools.
     
  “This report will increase public attention to these issues in Oregon, and provide Oregonians with a road map to create healthier learning environments for all Oregon students,” said Barbara Neely, RN, director of School Health Services for the Multnomah Education Service District and member of the task force.
     
  The recommendations to reduce environmental health threats include:
  
  * To reduce students’ exposure to pesticides, schools should control pests without pesticides whenever possible and completely avoid using pesticides when students are in school.
  * To reduce students’ exposure to diesel exhaust, school buses and other diesel vehicles should not idle for more than 2 or 3 minutes.
  * Schools should strive to purchase “green” cleaning chemicals to reduce students and employees exposure to toxic chemicals.
    
• Correction: A sentence in a recent piece by Michael Bowdoin (“Legally Speaking, Just Who Is An IAQ Expert?”, March 2003) appeared incorrectly. On page 28, the fourth sentence in the third full paragraph should have read, “For example, the program evaluates proficiency only in the testing of viable samples.”

Among the many bills circulating through state governments this spring is Florida Senate Bill 2746, the “Mold Remediation Registration Act.” Like similar bills introduced in Texas and other states, Fla. SB 2746 would regulate individuals and companies performing mold-related activities, including assessment, remediation and training.

SB 2746 would establish a state registry, and an individual or a company would be required to hold a registration issued by the Florida Department of Business and Professional Regulation to perform mold-related services.

Within SB 2746, several qualifications for registration are specified. These include that the registrants must be at least 18 years of age, be of good moral character, and have successfully met the requirements for registration established under the act. Among those registration requirements is a provision that the individual must meet the eligibility requirements set by the American [Industrial] Hygiene Association, the Indoor Air Quality Association, or an equivalent educational program as determined by state authorities.

While AIHA has been cited in legislation introduced in several other states, often in the context of exemptions from licensing for certified industrial hygienists, SB 2746 is the first instance where eligibility for IAQA programs would be among the state mandates for registration.

Many in the IAQ industry have hypothesized that AIHA lobbyists were responsible for the CIH exemptions seen in similar bills introduced this year in Texas, Nevada and Florida. AIHA officials deny any active lobbying in this area, and claim that the appearance of exemptions for CIHs occurred because of recognition that those holding the credential are qualified to perform mold work.

IAQA officials likewise deny having lobbied for inclusion of their programs in Fla. SB 2746. “We are pleased to see IAQA included in the bill, but we didn’t ask for it,” said Bob Baker, chairman of IAQA’s Government Affairs Committee.

According to IAQA officials, the association has a long-standing relationship with the Florida Construction Industry Licensing Board, which since the mid-1990s has awarded continuing education credits to HVAC contractors seeking state license renewal for attending IAQA courses. Earlier this year, the Florida board also approved IAQA courses for continuing education credit toward the renewal of professional engineers’ state licenses.

“We speculate that some of the people at the Florida Construction Industry Licensing Board were involved when SB 2746 was drafted,” Baker said. “Knowing the quality of IAQA programs and having worked with IAQA for so many years, they must have recognized that IAQA requirements would certainly meet or exceed any similar requirements created by the state.”

Ventilation is important to your health and the health of your home. Good ventilation is important to your comfort and safety, as is a reliable heating system, smoke alarm and a dry basement. It will help to protect the occupants from irritating pollutants and potentially dangerous gases like carbon monoxide or other combustion fumes.

Well-planned ventilation also helps to manage moisture during both the heating and cooling season, reducing the likelihood of either excess dryness or fungal growth.

Air Pollution Dynamics
The concentration of a particular air contaminant in the air we breathe inside a home is primarily dependent upon the rate at which the material is released in the home and how fast it leaves via local exhaust, dilution or air cleaning. How fast it is being released in a home depends upon what the source is. The contaminant could be something as simple as moisture from showering or more complicated like a damp basement floor or wall. Other typical sources include identifiable odors from burning something in the oven, scented glass enclosed candles, or tobacco. Another whole class of materials includes solvents slowly evaporating from furniture, building components, textile finishes, and hard surface finishes. The rate at which any of the above materials is removed or stale air is diluted from the home is determined by a combination of local exhaust fans, general dilution with a planned outdoor air inlet, or via air leakage or an opened window. Additionally, some type of air cleaning device may be utilized.

Are building tightness and ventilation a myth? Older homes, or newer homes with poorly constructed ductwork in attics or crawlspaces, often have three to five times more ventilation than they need for good health. Excess ventilation can lead to high heating or cooling energy costs, excess winter dryness and possible mold growth. For a specific home, the lower the general dilution rate from building leakage (the natural ventilation rate) the higher you might expect contaminant concentrations to become if the contaminant source is located within the home or in the earth under the home. However, it is important to note that over the past 20 years, large-scale measurement of contaminant levels in homes has not turned up a statistical connection of pollutant exposures to building tightness or natural leakage.

This observation confirms that how fast any material is being released inside the home is usually at least as important as the ventilation rate from air leakage or typical small residential fan powered ventilation devices. If a specific home were designed to leak just the right amount of ventilation air (natural leakage) at temperatures below 0, the leakage area would not provide enough fresh air when the temperatures are at or above freezing.

That is, the rate of building leakage is strongly inversely proportional to temperature difference: The colder it is, the more air leakage you get through a given hole. In heating climates, too much air leakage means greater heating bills and very dry indoor conditions. In a cooling climate, too much air leakage means greater cooling bills and likely excess humidity problems. These are the reasons that “build tight and ventilate right” is the way most homes have been constructed for much of the past 25 years.

Tight Homes And IAQ
Airtight, well-insulated homes with proper foundation moisture-management features for the climate zone they are built in, as a class, are no more likely to have an air quality problem than old poorly insulated homes with high uncontrolled air leakage rates or poor moisture management. This is why it is recommended today to construct homes to be energy efficient, well insulated and airtight and to provide the correct amount of planned ventilation air with mechanical means (fans), instead of relying on uncontrolled natural ventilation (building air leakage). Therefore, basement designs for hot and dry climates must be different than temperate and wet climates like most of the eastern United States.

For some mild climates, an alternative to the approach of using fans to move ventilation air is to have multiple manually controlled air leakage sites that are opened or closed as the weather and occupants’ needs change. Additionally, in some areas of the country, regardless of home tightness, very special exhaust systems are needed for dealing with pollutants under homes such as radon from soil gases. Radon removal systems use a small long-life fan installed to slightly depressurize the soil under the home to capture radon gas from the soil before it enters a home or crawlspace and move it to the outdoors. These same long-life, low power-consumption radon fans are now also used to provide quiet reliable low-level whole house ventilation.

Keeping Hazards Out
Even with adequate ventilation, it is important to recognize that keeping unusually strong pollutant sources such as strong cleaning compounds or liquid fuels out of a home is a vital part of good home management. Any hazardous liquid material that evaporates from a container should be stored outside of the home, or if it must be inside a home or a garage in a fire safe spaces where the air is continuously exhausted. Ventilation ducts that move air to or form a home should not be located in attached garages or buried in the earth. Garages should be isolated from the home as much as possible.

How Much VentilationIs Enough?
There are two basic approaches to ventilation: exhaust ventilation for localized pollutant sources (because it’s the most cost effective way to deal with the pollutant) and general dilution ventilation for the whole home.

In most home ventilation system designs today, wall switch-controlled mechanical ventilation units (small exhaust fans) remove locally generated contaminants at their source. Typical sources include moisture from showers and tubs and odors from bathrooms, kitchens or hobbies. These exhaust systems are designed to provide air movement rates that meet building codes and standards. They are also designed to be capable of providing reliable intermittent exhaust flow that move pollutants out of the home and at the same time pull outdoor air (fresh air) in for the occupants. Some states now require suitable designated entry sites for the exhaust make up air that these fans pull out. Some of the exhaust fans can be left on for long time periods to provide general ventilation if they are specified to be long life and quiet; i.e., there are a variety of bath and kitchen exhaust fans available and not all are designed for continuous low level use. It is in general always most cost effective to remove pollutants at their source using local exhaust.

When the windows and doors of a home are closed, the entry points for the outdoor air moved by exhaust fans can either be planned openings or uncontrolled air leakage sites. There are varieties of general ventilation systems available to move ventilation air. They can be as simple as installing a long life quiet fan attached to multiple bathrooms and a kitchen that runs nearly continuously, or they can be more complicated, incorporating an energy recovery device or dehumidifying device. Fresh air supply can be a stand alone designated opening, or it can be an opening incorporated into a central furnace or air conditioning unit. A designated opening is required by some state codes.

In a few climates in the United States, the outdoor air is often both comfortable and clean. In these areas, open windows may reduce the need for mechanical fans and air filters to move clean air into a home and dirty air out of a home.

In climates where the home is either heated or air conditioned for long periods of time, a general ventilation system that provides both supply and local exhaust air that also recovers total energy likely makes sense. These energy recovery devices also can incorporate medium efficiency particle air filters that will remove most pollen and mold spores. These devices can also be set up to move contaminated air out of rooms that have sources of contaminants and to provide clean filtered and pre-condition outdoor air into rooms where people spend a lot of their time. See www.renewaire.com.

In many coastal climates, or during certain swing seasons, where excess outdoor humidity is a concern, a dehumidifier that also brings in and dehumidifies outdoor air may be a very wise choice. This type of a device may be of particular use in basement areas or in older homes were cool damp basements may be prone to mold growth during certain times of the year. These devices can also incorporate particle air filters for removing most pollen and mold spores. These dehumidifying air cleaners are very efficient and economical to operate and can remove up to 100 pints a day of excess humidity from the air in a home. See www.thermastor.com.

Ventilation Guidelines
How much air? Most residential building codes now reference standards for ventilation in residential facilities. Standards by ASHRAE specify the option of intermittent ventilation in multiple areas, or continuous low-level ventilation for the whole home, or both. Ventilation systems that will meet this standard consist of either a central fan or fans, or multiple fans that are used to create pressure differences to move air out of a specific room and out of the home. Ventilation systems can also include openings for passive or fan powered makeup air, to move makeup air for the exhaust into the home directly or into a furnace of A/C unit.

Ventilation fans have some type of electrical control. The control can be as simple as a fan tied into a bathroom light switch or a bathroom or basement humidity thermostat (humidistat) or more sophisticated such as a programmable intermittent controller offered by several manufacturers. See www.aircycler.com. If a basement dehumidistat is used, one must remember to turn it off in the summer.

The ventilation system may have planned air intakes, air exhausts, or both. If it has both, they would normally be kept a specified distance apart. Some state require planned air intakes.

Often, a coarse, disposable fiberglass filter, reusable metal or plastic filter – that is easy to see through – is incorporated into ventilation systems to keep insects out and the fan or a cooling coil from clogging. These course filters will do little to clean the air and they should be replaced with at least a moderate efficiency pleated filter that is effective for removing pollen and mold spores. In general, an extended surface pleated filter will provide superior air filtration, long life and not restrict airflow. A good rule of thumb is the more difficult it is to see through the filter and the deeper and more multiple the pleats, the better it will work and the longer it will last. HEPA or near-HEPA filters are available from several manufactures for retrofit into a heating, cooling, dehumidifying or ventilation system. Manufacturers’ installation guidelines should always be followed. Most central-type electronic air cleaners work well when new, but they must be cleaned frequently to keep them working as designed. Air cleaners that release materials into the air of the home to purify the air and remove pollutants during their operation are not likely a wise investment. If it sounds too good, it likely is. Check for consumer or government guidelines on the use of certain devices.

Viable and non-viable organisms – mold and other materials with an organic origin – are often found in the indoor air. include dust mites, viruses, bacteria, fungi, animal dander and fur. Many people can have severe allergic reactions to these organisms. Exposures to some organisms are associated with fatal disease, e.g., Legionnaires’ disease, hantavirus, drug-resistant tuberculosis. As noted above, good particle air filters will capture much of the materials after they are released in a home. Keeping the relative humidity in a home up to 30 percent in the winter and down to 50 percent in the cooling season will minimize the growth of many of the living organisms and improve occupant comfort.

However, homes in heating climates should seldom be humidified above 30 percent in the winter, or excess mold growth may occur in or on building components. If humidity is added, it is generally safe to add in small amounts with clean steam, or some other type of very vigorously maintained device. Air conditioned homes should be kept at 60 percent RH or lower during the cooling season, or excess mold growth is likely to occur on any cold surface in the home. It is important to not oversize A/C systems or the home will become cool and clammy during part load operation.

It is generally recommended tightly constructed houses have outside combustion air supplied directly to all combustion devices in the building in accordance with the manufacturers recommendations. A back-drafting check made by a qualified technician is recommended to make sure any naturally vented combustion appliances do not release combustion fumes into the home when exhaust fans are operated. This is especially true if there is a large downdraft kitchen exhaust as part of a cooking surface, as they move large quantities of air to attempt to stop hot gasses and odors from rising.

Temporary Ventilation And Hazardous Materials In A Building
When utilizing odiferous or hazardous aerosols, or materials that are applied in liquid form, it is imperative that the manufacturers’ directions be carefully followed. “Well ventilated area” may frequently mean that one window is opened on one side or a room, and that on the other side of a room, a 20-inch window fan is sealed onto a sheet of plywood to suck fumes out of the room. This level of ventilation is often needed during home remodeling, even if it means leaving the heat set up at 72 degrees with a window open. If it can be arranged, outdoors is probably the safest place to use very odiferous or hazardous products. Less noxious or hazardous materials that accomplish the same task are increasingly available.

If recognized potentially hazardous or irritating materials such as mold, lead paint, asbestos or fibrous insulation are to be disturbed inside a home, it should only be done following recommended procedures of containment and isolation in accordance with local laws and good practice to avoid spreading the materials to other locations or exposures to the occupants.

With some types of contaminants, it is very easy to identify a pollutant source problem that needs to be addressed. Anything that has a noticeable odor when you enter a home can be obvious, for example, sewer gas from a leaky fitting, propane or natural gas from a leaking gas fixture or pilot light, or mold smells from microbial growth sites located indoors. If formaldehyde or other VOCs are present in high enough concentrations to be smelled, then it may be strong enough to pose problems to sensitive people.

Moisture in a heating climate can sometimes be seen condensing on windows, and if this situation last for any length of time, mold will likely soon show up on cold Sheetrock surfaces behind furniture. Mildew smells in closets or other low ventilation places need to be mitigated; they indicate too much moisture or too little wall insulation or too little air movement, or all of the above. An inexpensive hygrometer can tell you what the RH inside the home or crawlspace is. The digital units frequently cost less than $40 and are typically accurate from 20—80 percent RH.

The likely presence of other pollutants can be guessed by the presence of sources. An operating unvented heater is likely giving off combustion byproducts at potentially unhealthy or irritating levels unless it is located in a very well ventilated area. An entire room of new unfinished pressed wood shelving is likely outgassing some formaldehyde. Unvented gas ranges or gas ovens, inappropriately being used for heating instead of cooking, and cigarette smoking, or large sooty candles can be obvious to the eye.

If a homeowner has a basic ventilation system and is concerned with pollutants levels, there are some passive monitoring devices available for radon, mold, nitrogen dioxide, carbon monoxide and formaldehyde. Active monitors are readily available for carbon monoxide and combustible gases. Beware of misinterpreting results and making a large or economic decision based on an inexpensive measurement.

In Closing
Homes as a system are not rocket science; they are in fact often more complicated, as the builder often has little control of how the occupant will actually use the home even when a detailed owner’s manual is provided. The ventilation system is an important part of the other systems as a whole; it is intended to keep moisture (from precipitation and the ground) out of the indoor environment and to keep the occupants inside comfortable.

In general, ventilation guidelines and codes are not intended to address misuse of the appliance or very high occupant densities. Ventilation systems in homes often work quite well until some combination of uses and misuses, changes of use, and a lack of maintenance render the systems as installed inadequate. On the other hand, systems that are installed in accordance with current guidelines, utilized as intended, and maintained, have a high probability of not contributing to IAQ problems and should help prevent them.

William A. Turner, MS, PE is president of Turner Building Science LLC, a subsidiary of the H.L. Turner Group Inc. in Concord, N.H. He has more than 25 years of experience in IAQ/HVAC evaluation and development of solutions for building system problems. Turner supervises a group of mechanical engineers, industrial hygienists and building scientists who focus on developing solutions for existing facilities and the design of high-performance buildings. You can be reach him by calling (207) 583-4571 ext. 11 or by e-mail at bturner@ hlturner.com.