Indoor Air Quality

The U.S. Environmental Protection Agency (EPA) has rated indoor air pollution as one of the five most urgent environmental issues, accounting for over $1 billion in direct health care costs annually. The culprit is improper ventilation and poor building practices. Shouldn’t your home be a safe haven for your family?

During the 1990s, the EPA rated indoor air pollution as one of the five most urgent environmental issues, accounting for over $1 billion in direct health care costs annually. The culprit is improper ventilation and poor building practices.

With the focus on improving building standards, each step in the process is being scrutinized and improved, especially the insulation process. SEALECTION 500 is well ahead on the technology curve when it comes to improving indoor air quality.

SEALECTION 500 is an environmentally safe and non-toxic product that completely air seals a building. Combined with proper mechanical ventilation, SEALECTION 500 is the answer to improving indoor air quality and creating a healthy, clean environment.

According to the American Lung Association, in excess of 40% of American households have at least one person suffering from asthma or allergies making the quality of indoor air crucial to their good health. Properly insulating a home can have a positive impact on the quality of the indoor air.

By sealing out dust, allergens, odors and pollutants SEALECTION 500 allows the air management system to be designed so that the indoor air quality is healthier than outside air.

Shouldn’t your home be a safe haven for your family?

Indoor Air Quality and Air Duct Cleaning

Whether or not you have the ductwork cleaned, preventing water and dirt from entering the system is the most effective way to prevent contamination.

Most people are now aware that indoor air pollution is an issue of growing concern and increased visibility. There are many things to consider before you decide if the air ducts of your building should be cleaned.

Sizing the HVAC: Bigger Is Not Better

It is generally accepted that “the right way” to specify an air conditioning system is to calculate the loads and select a piece of equipment that will provide comfort to the customer in a wide variety of conditions. Unfortunately this is rarely practiced.

Bigger is Not Better Summary

Since optimum efficiency is achieved at continuous running, it is important that the air conditioner be sized to achieve the longest run times possible. Standard sizing calculations are based on a design temperature that is exceeded only 73 hours in a normal cooling season. An air conditioner sized to run continuously at design conditions will cost less initially and will have a lower operating cost due to its longer run times.

Primary Recommendations

Air Conditioning Contractors of America (ACCA) has produced a number of design manuals (Manuals J, S, D, and T) that produce far better results than the rough and tumble rules of thumb that are used by the vast majority of HVAC contractors. A contractor will achieve (and their customer will enjoy) a much higher quality job if these manuals are followed in the design and installation of central air conditioning systems.

A recent investigation of new houses has shown that an air conditioner delivering a capacity equal to Manual J would be adequate even during extrodinarily hot summers.

The primary problems in the field include improperly sized air conditioners, improperly designed duct systems poor grille selection, and poor installation of all three components. These problems are most easily avoided in new construction; but retrofit situations will also benefit from following the recomendations in this article whenever they can be applied.

The Disadvantages of Improperly Sized Equipment

In recent years Proctor Engineering Group has investigated air conditioner comfort, efficiency, and economy in a wide range of locations. One interview with a home owner in Palm Springs, California, summarizes a number of issues that we have found repeatedly. This house was a moderate sized older home with beautiful overhangs shading the east and west windows.

I was invited to sit at the kitchen table to talk with the owner, a man in his early 60s. He complained that his cooling bills were high and he was never comfortable during the cooling season (which extends over most of the year in Palm Springs). As we talked the air conditioner came on and a strong stream of cold air moved by my shoulder. The owner got up, went over to the supply register and closed the damper. He came back to the table explaining that with the register open he was blasted with cold air that made him uncomfortable. The noise coming from the closed register made it hard to have a conversation at the table. I asked him about that problem and he responded that the system was always noisy. When I suggested that we move to another room for our conversation, he said, “That wouldn’t make any difference, there are only hot places and cold places, no place is right in this house. We are looking for a new house.”

The situation we found in this house exists, in various degrees, in millions of homes across the United States. The heating and cooling distribution system was not matched to the cooling loads of the individual rooms nor to the needs of the occupants. On top of that, the air conditioner was not matched to the distribution system. Discomfort and expense are the inevitable results of these mismatches.

Bigger is not Better. Comfort is Better.

In 1923, in effort to pinpoint the indoor environment conditions that make people comfortable, F.C. Houghten and C.P. Yaglou, conducted studies to determine how people feel under varying temperature and humidity conditions. The result of this research was the identification of a “comfort zone” based on temperature and humidity. As you know, your tolerance to heat is affected by the amount of humidity in the air. At higher temperatures the humidity level must be held lower to ensure comfort.

The comfort zone was found to be acceptable to 90% of test subjects drawn from a range of age groups and genders with work and life styles involving varying levels of activity and clothing. An air conditioning system that establishes and maintains indoor conditions that are within this zone will provide thermal comfort. It will produce a neutral sensation; occupants will feel neither too hot nor too cold.

An air conditioner can easily bring the temperature inside a house into the comfort range. In fact, bigger air conditioners virtually ensure that the temperature at the thermostat can be as cold as you set it. Unfortunately, cold alone is not comfortable. In fact it is distinctly uncomfortable. To maintain a general level of comfort the moisture level must also be controlled and moisture control is best achieved by smaller, not larger, air conditioners.

Smaller Units Remove More Moisture

An air conditioner’s ability to remove moisture increases when the equipment runs for longer periods of time. At the beginning of every cycle in hot moist climates, the air conditioner puts moisture into the house as water is evaporated off the inside coil. Since a smaller air conditioner runs longer to keep the house at the temperature set point, it removes more moisture than a larger unit would be able to achieve.

A 5-ton unit X, running for five minutes would remove 1.4 pounds of water. A 2.5-ton air conditioner, in the same house, running for ten minutes would remove 1.7 pounds of moisture. This is an increase in moisture removal of 21%.

The amount of moisture removed is not only a function of how long the air conditioner runs, but also its Sensible Heat Ratio (SHR – the percentage of the total capacity delivered as lower house temperature.)

A low Sensible Heat Ratio will result in more moisture removal. For hot wet climates where moisture removal is important , air flow across the coil should be reduced slightly to increase the SHR and the air conditioner condensing unit and indoor coil combination should be chosen to have a low SHR. Please note, if you don’t use the outdoor unit manufacturer’s indoor coil, you cannot use their published SHR.

Typical matched units from major manufacturers have Sensible Heat Ratios in the 68% to 80% range when it is 95F outside and 75F with 50% relative humidity inside.

Even Temperatures are Necessary for Comfort.

Our homeowner in Palm Springs didn’t have a problem with moisture, but he did have a problem with uneven temperatures. When the air conditioner was on, portions of his home and even different parts of individual rooms were at significantly different temperatures. Stagnation of air in one part of a room (one corner, at head level, etc.) makes people uncomfortable. Proper mixing of the air and proper distribution to individual rooms avoids this problem.

The following describes two methods designers can use when attempting to get proper distribution and mixing of the air.

An old method is to use a large air handler fan to circulate air all or most of the time. This is sometimes effective in mixing the air but at a high price. There is an old rule of thumb that between four and six house volumes of air must pass through the air handler in an hour. At six air changes this means a 1400 sf. home would have to have a continuously running fan that delivers 1120 CFM (equivalent to almost 3 tons) regardless of the cooling load of the house. The common practice is to install an air conditioner (inside and outside unit) with the capacity to meet those flow requirements.

There are many disadvantages to this scenario:

  • the need for a larger and more expensive duct system to handle the increased flow
  • increased duct conduction due to constant circulation and the larger surface area of duct system
  • reduced latent capacity due to constant circulation and short compressor cycles (caused by the oversized outdoor unit)
  • increased cooling load due to duct leakage effects and fan energy delivered as heat

A better solution is, to design and install a delivery system that properly distributes the cooling to each room, then to select and place supply grilles that promote mixing by “throwing” the delivered air into the right places in the room. Air Conditioning Contractors of America has produced manuals to guide contractors in this process (Manual D-Duct Design and Manual T-Terminal Design).These Manuals lead the installing contractor through the process of selecting the proper size duct and type of register based on the location of the register, size of the room, restriction the duct run, and the dimensions and heat gain of the room. Unfortunately, only the best contractors and builders ever pay attention to these critical details.

The problems of stagnation and overheating can be reduced by proper implementation of ACCA procedures. These problems can be further reduced by ensuring that the assumptions built into these manuals are not violated. For example, it is assumed that there is no duct leakage in the system. Any long time reader of Home Energy will immediately note that this assumption is violated in nearly all homes (including new ones). Proper installation of the duct system and leakage testing are essential to obtain comfort.

Another assumption is that the conduction losses are the same percentage of the delivered cooling regardless of the length of the duct run. This would be an insignificant assumption in a heavily insulated system (and R-4 is not heavily insulated). Long duct runs through the attic loose over 15% of their cooling capacity before the conditioned air reaches its destination. Long duct runs need additional insulation to deliver the proper amount of cooling to the distant rooms.

Uneven temperatures have become more common due to the “modern” practice of severely reducing overhangs above the windows. Without overhangs, rooms with west facing windows will overheat in the afternoon since their need for cooling can easily double.

Drafts Destroy Comfort.

A draft exists when unwanted air movement causes cooling on one part of your body. The colder the air and the faster it is blowing, the more offensive drafts are. Air conditioning drafts are characterized by cold, high velocity air striking your body. Studies show that these drafts are even more offensive if they are intermittent.

An oversized air conditioners is a major contributor to drafts. An oversized air conditioner is almost always married to a duct system that is unable to deliver the amount of air necessary for proper air conditioner performance (more on this later). The result is a poor compromise air flow that is too low for the air conditioner and too high for the duct system. The low air flow across the oversize coil produces colder delivery temperatures and the high air flow through the ducts and grilles produce high pressures, noise, and high velocities at the grilles. When low delivery temperatures are coupled with high velocity discharge through inappropriately selected (small and without proper throw or spread – often the cheapest) and poorly placed grilles, occupants experience drafts.

Bigger is not Better. Quiet is Better.

We all know how noisy forced air cooling systems can be. These noises can come from the grilles, the ducts, and from the fan. Our perception of noise is affected by both the frequency and the level of the sound. Higher frequency sounds (the sounds generated by high discharge velocities at grilles) are more offensive than lower frequency sounds (the sounds generated by the fan). For grilles there is a Noise Criteria (NC) rating that mimics the human perception of sound. The NC for a particular grille increases as more air is forced through it.

When an air conditioner and duct system are properly sized to meet the cooling load, it is easier to distribute the cool air without being noisy. When a duct system is being designed, the NC level and face velocity of every supply grille should be considered and held below NC-25 and 700 fpm for a quiet system.

Grilles with dampers are invariably noisier than equivalent grilles without dampers. When the dampers are partially closed, the pressures and leaks in the ducts increase and the air flow across the coil is reduced. Occupants generally close dampers to redirect air to another room that they believe needs more delivery. If the system is designed correctly dampers, either at the register or in line balancing, dampers should not be needed.

Bigger is not Better. Efficient is Better.

There is a lot of emphasis on the rated efficiency of air conditioners. Unfortunately, this necessary emphasis on equipment design has overshadowed efforts to improve the selection and installation of the entire air conditioning system. It is incorrectly assumed by builders, contractors, and the buying public, that if you spend the money on a high efficiency air conditioner you have gotten all the efficiency you can. But common problems such as oversizing, improper installation, low air flow, and leaky duct systems mean that customers don’t get the efficiency they paid a premium for.

A System with Correct Air Flow Helps Make an Efficient System.

Most air conditioners are designed to have 400 CFM per ton of air flow across the inside coil. When the air conditioner is coupled with a duct system that meets Manual D criteria, the proper flow is achieved. However, since air conditioners are commonly oversized for the heat gain of the home and the duct systems are not designed to Manual D even new systems are usually deficient in air flow. This situation only gets worse as the inside coil picks up dirt. In a recent laboratory test of a high efficiency air conditioner, Proctor Engineering Group found a 7 % drop in efficiency when the air flow was reduced by 30%. In order to ensure that the design air flow is being achieved, the installing contractor must measure the air flow across the inside coil. An Air Conditioner with Proper Charge Helps Make an Efficient System. A new split system air conditioner comes from the factory with the proper amount of factory installed charge for a standard length set of refrigerant lines. When the unit is installed, the contractor needs to evacuate the lines and indoor coil and weigh in any additional charge needed for the line set length increase over the standard length. Most of the time this is not done. This results in, leaks not being detected, air and moisture being captured in the line set and coil, and the unit ends up undercharged. In many cases the amount of undercharge is severe.

In the summer of 1995, Proctor Engineering Group and Arizona Public Service Company monitored a group of twenty two newly constructed homes. Nearly all of those homes had undercharged air conditioners. One of the worst units had 62% of correct charge (and 79% of proper flow). The homeowner complained to the builder that the air conditioner was not working right. She was told that the wrong amount of insulation had been installed in her attic and an insulation contractor was called in to apply additional insulation. Eliminating Duct Leaks Helps Make an Efficient System. Shortly thereafter the true problem showed itself when the air conditioner compressor failed. The evidence against leaky and underinsulated ducts continues to mount. Leaky ducts are a large contributor to system inefficiency and the negative effect increases with outdoor temperature. The Arizona Public Service Company test found that sealing a 13% supply leak saved 22% of the cooling energy consumption in the 100F to 105F temperature range. To ensure a tight duct system the installing contractor will have to do a test of duct integrity using specialized tools. (See the Sept/Oct 93 issue of Home Energy for more information on duct testing.) A Smaller Air Conditioner Helps Make an Efficient System. Air conditioners are very inefficient when they first start operation. It is far better for the air conditioner to run longer cycles than shorter ones. The efficiency of the typical air conditioner increases the longer it runs. For example, increasing the run time from 5 minutes to 9 minutes resulted in a savings of 10% for the unit described in “Bigger is not Better” HE May/June 1995. Because of the inefficiencies associated with the start up of the air conditioner, under most conditions, a smaller air conditioner will produce the same amount of cooling with lower energy consumption. Bigger is not Better.

But How Big is Big Enough? An air conditioner sized to ACCA Manuals J and S is big enough. Industry specialists who design and sell air conditioners have long used Manual J as a standard method for determining the amount of cooling needed to deliver thermal comfort to single family residences. The procedure is used to calculate room-by-room loads for duct design purposes and whole house loads for equipment selection. It was jointly developed by the Air Conditioning Contractors of America (ACCA) and the Air-Conditioning and Refrigeration Institute (ARI), and it is based on a number of sources including the ASHRAE Handbook of Fundamentals. Despite the widespread use of this procedure, many contractors have been reluctant to accept the ability of Manual J to deliver adequate cooling under design conditions. One reason for this reluctance has been the lack of information about how actual cooling loads compare to Manual J estimates. While many who have used Manual J extensively have long suspected it has an oversizing margin; field studies had not been performed to verify this anecdotal evidence. New data show that Manual J overestimates the sensible cooling load in hot dry climates. It is likely that the same is true of the sensible load in hot moist climates. Proctor Engineering Group, Electric Power Research Institute, Nevada Power, and Arizona Public Service monitored air conditioning systems installed in new homes in Phoenix, Arizona and Las Vegas, Nevada. By testing the actual cooling capacity required to maintain comfort under severe conditions, these tests have yielded the first measurements that confirm and quantify the overestimation present in Manual J. The studies showed that even when faced with an extraordinarily hot summer when almost 200 hours exceeded design conditions (design conditions are exceeded only 73 hours in a typical summer), the actual sensible cooling loads of the houses were less than Manual J estimates.

At the most intensively monitored sites in the studies, the data aquisition equipment recorded air flow, temperature drop and moisture removed from the conditioned air . The research team calculated the actual capacity delivered by the air conditioner for every air conditioner cycle. The systems were monitored from July 30 through September 25, 1995. Occupants were free to adjust their thermostat settings to any value, but most kept a constant thermostat setting. Most of the systems monitored were typical installations (including leaky ducts that increase the cooling load that the equipment needed to deliver). One typical house illustrates the overestimation contained in Manual J. System 26 had an 11.6% return leak and a 6% supply leak Figure 2 displays the hourly sensible cooling load against the outdoor temperature. Outdoor temperatures at this house ranged as high as 116F (according to ASHRAE Fundamentals the mean extreme temperature for Phoenix is 112.8F.) Even though this time period was extra ordinarily hot, the sensible load requirements for all but 3 hours (0.2%) of the 1316 monitored hours the load was less than Manual J estimated cooling load. Manual J overpredicted the design load for this house by almost 50%. These data illustrate that there was no need to oversize the air conditioner beyond the Manual J cooling load because Manual J already overestimates that load. In fact, the air conditioner installed in this house had a design sensible capacity 24% larger than Manual J and that excess capacity was not useful. Because of the oversizing however, the homeowners paid approximately $330 in additional first costs and they will pay additional unnecessary operating costs every summer month for the life of the system. Using Your Foot for Target Practice We know designers who determine the system air flow based on floor area (this oversizes the air conditioner in energy efficient homes), then try to squeeze down the size of the duct system so that it can be installed in the house. They explain that they can’t use a higher insulation level on the ducts because there is no room, and when faced with poor performance, increase the size of the air conditioner.

If the goal is comfort or efficiency, they are shooting themselves in the foot. Summary It is not uncommon for poor cooling performance to be attributed to insufficient equipment size when in fact there is more than enough cooling capacity. Usually, in a residential system, this situation is caused by poor design and installation that: reduce the capacity of the system by incorrect charge, low air flow, and duct leakage, cause noise, drafts, and uneven cooling by using an oversized air conditioner relative to the cooling load and undersized ducts relative to the oversized unit. Most household air conditioning problems will be eliminated when the capacity of the air conditioner is reduced to ACCA Manual J and Manual S standards, an appropriately designed, insulated, and leak-proof distribution system is used, and the system is installed to meet the manufacturer’s standards. These systems will have higher efficiencies because they will run longer cycles and will circulate air as needed a larger percentage of time. Properly designed and installed air conditioners are reliable and will deliver comfort to each room of the house for less cost. Recommendations Summary List * Wherever possible reduce the cooling load of the house. Overhangs above east and west windows are particularly effective in reducing cooling load. * Perform Manual J for all installations and select equipment using Manual S. * Ensure that the system installed never exceeds the capacity of the equipment suggested by Manual S. * Size duct systems based on Manual D. If in doubt size upwards. * Determine the grille location and characteristics using Manual T. * Confirm proper evacuation of the line set and indoor coil with a micron guage. * Confirm proper charge using the manufacturer’s suggested method. * Confirm proper airflow by test. The flow can be determined from the coil pressure drop when pressure/flow data is available from the coil manufacturer or can be determined with a duct test rig or flow hood. * Increase the duct insulation above R-4 (at least on long runs in the attic.) * Confirm that the duct leakage is less than 3% of coil air flow for a new system and less than 6% of coil air flow for an existing system. The report discussed in this article is available from Proctor Engineering Group, 818 Fifth Ave., Suite 208, San Rafael, CA 94901. This article is reprinted from a series on energy-efficient remodeling, which is being funded by the Environmental Protection Agency and the Department of Energy.

Molds in Homes

Molds produce tiny spores to reproduce. Mold spores waft through the indoor and outdoor air continually. When mold spores land on a damp spot indoors, they may begin growing and digesting whatever they are growing on in order to survive. The key to mold control is moisture control. More.. Introduction to Molds Molds produce tiny spores to reproduce. Mold spores waft through the indoor and outdoor air continually. When mold spores land on a damp spot indoors, they may begin growing and digesting whatever they are growing on in order to survive. Molds can grow on wood, paper, carpet, and foods. When excessive moisture or water accumulates indoors, mold growth will often occur, particularly if the moisture problem remains undiscovered or un-addressed. There is no practical way to eliminate all mold and mold spores in the indoor environment; the most appropriate way to control mold growth is to control moisture.

Basic Mold Cleanup

The key to mold control is moisture control. It is important to dry water damaged areas and items within 24-48 hours to prevent mold growth. If mold is a problem in your home, clean up the mold and get rid of the excess water or moisture. Fix leaky plumbing or other sources of water. Wash mold off hard surfaces with detergent and water, and dry completely. Absorbent materials (such as ceiling tiles & carpet) that become moldy may have to be replaced.

Ten Things You Should Know About Mold

  1. Potential health effects and symptoms associated with mold exposures include allergic reactions, asthma, and other respiratory complaints.
  2. There is no practical way to eliminate all mold and mold spores in the indoor environment; the way to control indoor mold growth is to control moisture.
  3. If mold is a problem in your home or school, you must clean up the mold and eliminate sources of moisture.
  4. Fix the source of the water problem or leak to prevent mold growth.
  5. Reduce indoor humidity (to 30-60% ) to decrease mold growth by: venting bathrooms, dryers, and other moisture-generating sources to the outside; using air conditioners and de-humidifiers; increasing ventilation; and using exhaust fans whenever cooking, dishwashing, and cleaning.
  6. Clean and dry any damp or wet building materials and furnishings within 24-48 hours to prevent mold growth.
  7. Clean mold off hard surfaces with water and detergent, and dry completely.
  8. Absorbent materials such as ceiling tiles, that are moldy, may need to be replaced.
  9. Prevent condensation: Reduce the potential for condensation on cold surfaces (i.e., windows, piping, exterior walls, roof, or floors) by adding insulation.
  10. Use low air permeable insulation such as SEALECTION 500 to insulate walls and ceilings.

Stop hot, moist air to enter or leave the building uncontrollably through the walls. In areas where there is a perpetual moisture problem, do not install carpeting near drinking fountains, classroom sinks, or on concrete floors with leaks or frequent condensation. Molds can be found almost anywhere; they can grow on virtually any substance, providing moisture is present. There are molds that can grow on wood, paper, carpet, and foods. If you have IAQ and mold issues in your school, you should get a copy of the IAQ Tools for Schools Kit. Mold is covered in the IAQ Coordinator’s Guide under Appendix H – Mold and Moisture.

Asthma and Mold Molds can trigger asthma episodes in sensitive individuals with asthma. People with asthma should avoid contact with or exposure to molds. EPA’s Asthma Web site EPA’s Asthma Publications and Resources EPA’s Mold page from Asthma Web site * Allergy & Asthma Network/Mothers of Asthmatics (AAN/MA): (800) 878-4403; * American Academy of Allergy, Asthma & Immunology (AAAAI): * American Lung Association: 1-800-LUNG-USA (1-800-586-4872); * Asthma & Allergy Foundation of America: (800) 7ASTHMA; * Canada Mortgage & Housing Corporation fact sheets on mold – * National Institute of Allergy and Infectious Diseases: * National Jewish Medical and Research Center: (800) 222-LUNG (5864);


Mold growth may be a problem after flooding. EPA’s Fact Sheet: Flood Cleanup: Avoiding Indoor Air Quality Problems – discusses steps to take when cleaning and repairing a home after flooding. Excess moisture in the home is cause for concern about indoor air quality primarily because it provides breeding conditions for microorganisms. This fact sheet provides tips to avoid creating indoor air quality problems during cleanup. Federal Emergency Management Agency (FEMA): (800) 480-2520; mitigation website: publications on floods, flood proofing, etc. University of Minnesota, Department of Environmental Health & Safety – “Managing Water Infiltration Into Buildings.” A Systematized Approach for Remediating Water Problems in Buildings due to Floods, Roof Leaks, Potable Water Leaks, Sewage Backup, Steam Leaks and Groundwater Infiltration. Questions and comments may be directed to: Neil Carlson, M.S., CIH, Department of Environmental Health & Safety, University of Minnesota, or Arif Quraishi, M.E., Vice President, Special Projects, Indoor Environments Division, Institute for Environmental Assessment, Inc. Health and Mold Molds can trigger asthma episodes in sensitive individuals with asthma (see Asthma Section above); molds can also trigger allergies in sensitive individuals. EPA’s publication, Indoor Air Pollution: An Introduction for Health Professionals, assists health professionals (especially the primary care physician) in diagnosis of patient symptoms that could be related to an indoor air pollution problem. It addresses the health problems that may be caused by contaminants encountered daily in the home and office. Organized according to pollutant or pollutant groups such as environmental tobacco smoke, VOCs, biological pollutants, and sick building syndrome, this booklet lists key signs and symptoms from exposure to these pollutants, provides a diagnostic checklist and quick reference summary, and includes suggestions for remedial action. Also includes references for information contained in each section. This booklet was developed by the American Lung Association, the American Medical Association, the U.S. Consumer Product Safety Commission, and the EPA. EPA Document Reference Number 402-R-94-007, 1994. Allergic Reactions – excerpted from Indoor Air Pollution: An Introduction for Health Professionals section on: Animal Dander, Molds, Dust Mites, Other Biologicals. “A major concern associated with exposure to biological pollutants is allergic reactions, which range from rhinitis, nasal congestion, conjunctival inflammation, and urticaria to asthma. Notable triggers for these diseases are allergens derived from house dust mites; other arthropods, including cockroaches; pets (cats, dogs, birds, rodents); molds; and protein-containing furnishings, including feathers, kapok, etc. In occupational settings, more unusual allergens (e.g., bacterial enzymes, algae) have caused asthma epidemics. Probably most proteins of non-human origin can cause asthma in a subset of any appropriately exposed population.” Consult the Centers for Disease Control (CDC) website. CDC’s National Center for Environmental Health (NCEH) has a toll-free telephone number for information and FAXs, including a list of publications: NCEH Health Line 1-888-232-6789. CDC’s “Molds in the Environment” Factsheet Stachybotrys or Stachybotrys atra (chartarum) and health effects CDC’s “Questions and Answers on Stachybotrys chartarum and other molds” Homes and Molds The EPA publication, “A Brief Guide to Mold, Moisture, and Your Home”, is available here in HTML and PDF formats. This Guide provides information and guidance for homeowners and renters on how to clean up residential mold problems and how to prevent mold growth. A printed version will be available soon. Biological Pollutants in Your Home – This document explains indoor biological pollution, health effects of biological pollutants, and how to control their growth and buildup. One third to one half of all structures have damp conditions that may encourage development of pollutants such as molds and bacteria, which can cause allergic reactions — including asthma — and spread infectious diseases. Describes corrective measures for achieving moisture control and cleanliness. This brochure was prepared by the American Lung Association and the U.S. Consumer Product Safety Commission. EPA Document Reference Number 402-F-90-102, January 1990.

Moisture control is the key to mold control; the Moisture Control Section from Biological Pollutants in Your Home follows: Moisture Control Water in your home can come from many sources. Water can enter your home by leaking or by seeping through basement floors. Showers or even cooking can add moisture to the air in your home. The amount of moisture that the air in your home can hold depends on the temperature of the air. As the temperature goes down, the air is able to hold less moisture. This is why, in cold weather, moisture condenses on cold surfaces (for example, drops of water form on the inside of a window). This moisture can encourage biological pollutants to grow. There are many ways to control moisture in your home:

  1. Fix leaks and seepage. If water is entering the house from the outside, your options range from simple landscaping to extensive excavation and waterproofing. (The ground should slope away from the house.) Water in the basement can result from the lack of gutters or a water flow toward the house. Water leaks in pipes or around tubs and sinks can provide a place for biological pollutants to grow.
  2. Put a plastic cover over dirt in crawlspaces to prevent moisture from coming in from the ground. Be sure crawlspaces are well-ventilated.
  3. Use exhaust fans in bathrooms and kitchens to remove moisture to the outside (not into the attic). Vent your clothes dryer to the outside.
  4. Turn off certain appliances (such as humidifiers or kerosene heaters) if you notice moisture on windows and other surfaces.
  5. Use dehumidifiers and air conditioners, especially in hot, humid climates, to reduce moisture in the air; but be sure that the appliances themselves don’t become sources of biological pollutants.
  6. Raise the temperature of cold surfaces where moisture condenses. Use insulation or storm windows. (A storm window installed on the inside works better than one installed on the outside.)
  7. Open doors between rooms (especially doors to closets which may be colder than the rooms) to increase circulation. Circulation carries heat to the cold surfaces. Increase air circulation by using fans and by moving furniture from wall corners to promote air and heat circulation. Be sure that your house has a source of fresh air and can expel excessive moisture from the home.
  8. Pay special attention to carpet on concrete floors. Carpet can absorb moisture and serve as a place for biological pollutants to grow. Use area rugs which can be taken up and washed often. In certain climates, if carpet is to be installed over a concrete floor, it may be necessary to use a vapor barrier (plastic sheeting) over the concrete and cover that with sub-flooring (insulation covered with plywood) to prevent a moisture problem.
  9. Moisture problems and their solutions differ from one climate to another. The Northeast is cold and wet; the Southwest is hot and dry; the South is hot and wet; and the Western Mountain states are cold and dry. All of these regions can have moisture problems. For example, evaporative coolers used in the Southwest can encourage the growth of biological pollutants. In other hot regions, the use of air conditioners which cool the air too quickly may prevent the air conditioners from running long enough to remove excess moisture from the air. The types of construction and weatherization for the different climates can lead to different problems and solutions.

Moisture On Windows

Your humidistat is set too high if excessive moisture collects on windows and other cold surfaces. Excess humidity for a prolonged time can damage walls especially when outdoor air temperatures are very low. Excess moisture condenses on window glass because the glass is cold. Other sources of excess moisture besides overuse of a humidifier may be long showers, running water for other uses, boiling or steaming in cooking, plants, and drying clothes indoors. A tight, energy efficient house holds more moisture inside; you may need to run a kitchen or bath ventilating fan sometimes, or open a window briefly. Storm windows and caulking around windows keep the interior glass warmer and reduce condensation of moisture there. Humidifiers are not recommended for use in buildings without proper vapor barriers because of potential damage from moisture buildup. Consult a building contractor to determine the adequacy of the vapor barrier in your house. Use a humidity indicator to measure the relative humidity in your house. The American Society of Heating and Air Conditioning Engineers (ASHRAE) recommends these maximum indoor humidity levels: Outdoor Temperature ; Recommended Indoor Relative Humidity +20 F 35% +10 F 30% 0 F 25% -10 F 20% -20 F 15% Anne Field, Extension Specialist, Emeritus, with reference from the Association for Home Appliance Manufacturers ( ). Should You Have the Air Ducts in Your Home Cleaned? The EPA can guide you on Air Duct Cleaning. Indoor Air Regulations and Mold Threshold Limit Values (TLV’s) are guidelines (not standards) prepared by the American Conference of Governmental industrial Hygienists, Inc (ACGIH) to assist industrial hygienists in making decisions regarding safe levels of exposure to various hazards found in the workplace. A TLV reflects the level of exposure that the typical worker can experience without an unreasonable risk of disease or injury. TLVs are not quantitative estimates of risk at different exposure levels or by different routes of exposure.

What is SBS and what causes it?

Sick Building Syndrome (SBS) is a situation in which occupants of a building experience acute health effects that seem to be linked to time spent in a building. While specific causes of SBS remain unknown, the following have been cited as contributing factors to sick building syndrome: Chemical contaminants from outdoor sources Chemical contaminants from indoor sources What Is Sick Building Syndrome? Sick Building Syndrome (SBS) is a situation in which occupants of a building experience acute health effects that seem to be linked to time spent in a building, but no specific illness or cause can be identified. The complaints may be localized in a particular room or zone, or may be widespread throughout the building.

Frequently, problems result when a building is operated or maintained in a manner that is inconsistent with its original design or prescribed operating procedures. Sometimes indoor air problems are a result of poor building design or occupant activities. What Are the Symptoms of SBS? Building occupants complain of symptoms associated with acute discomfort. These symptoms include headaches; eye, nose, and throat irritation; a dry cough; dry or itchy skin; dizziness and nausea; difficulty in concentrating; fatigue; and sensitivity to odors. With SBS, no clinically defined disease or specific chemical or biological contaminant can be determined as the cause of the symptoms. Most of the complainants feel relief soon after leaving the building. SBS reduces worker productivity and may also increase absenteeism.

What Causes SBS? While specific causes of SBS remain unknown, the following have been cited as contributing factors to sick building syndrome. These elements may act in combination or may supplement other complaints such as inadequate temperature, humidity, or lighting.

  • Chemical contaminants from outdoor sources: Outdoor air that enters a building can also be a source of indoor pollution. Pollutants from motor vehicle exhausts, plumbing vents, and building exhausts (bathrooms and kitchens) can enter the building through poorly located air intake vents, windows, and other openings. Combustion byproducts can also enter a building from a nearby garage.
  • Chemical contaminants from indoor sources: Most indoor air pollution comes from sources inside the building. For example, adhesives, upholstery, carpeting, copy machines, manufactured wood products, cleaning agents and pesticides may emit volatile organic compounds (VOCs) including formaldehyde. Research shows that some VOCs can cause chronic and acute health effects at high concentrations, and some are known carcinogens. Low to moderate levels of multiple VOCs may also produce acute reactions in some individuals. Environmental tobacco smoke and combustion products from stoves, fireplaces, and unvented space heaters all can put chemical contaminants into the air. It can also come from synthetic fragrances in personal care products or in cleaning and maintenance products.
  • Biological contaminants: Biological contaminants include pollen, bacteria, viruses, and molds. These contaminants can breed in stagnant water that has accumulated in humidifiers, drain pans, and ducts, or where water has collected on ceiling tiles, insulation, or carpet. Biological contaminants can cause fever, chills, cough, chest tightness, muscle aches, and allergic reactions. One indoor air bacterium, Legionella, has caused both Pontiac Fever and Legionnaire’s Disease.
  • Inadequate ventilation: In the 1970s the oil embargo led building designers to make buildings more airtight, with less outdoor air ventilation, in order to improve energy efficiency. These reduced ventilation rates have been found to be, in many cases, inadequate to maintain the health and comfort of building occupants. What Are the Solutions to Sick Building Syndrome? Solutions to SBS problems usually include combinations of the following measures:
  • Increasing the ventilation rates and air distribution is often a cost-effective means of reducing indoor pollutant levels. At a minimum, heating, ventilating, and air conditioning (HVAC) systems should be designed to meet ventilation standards in local building codes. Make sure that the system is operated and maintained to ensure that the design ventilation rates are attained. If possible, the HVAC system should be operated to the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 62-1989. If there are strong pollutant sources, air may need to be vented directly to the outside. This method is especially recommended to remove pollutants that accumulate in specific areas such as restrooms, copy rooms, and printing facilities.
  • Removal or modification of the pollutant source is the most effective approach to solving a known source of an indoor air quality problem when this solution is practicable. Ways to do this include routine maintenance of HVAC systems; replacing water-stained ceiling tiles and carpets; banning smoking or providing a separately ventilated room; venting contaminant source emissions to the outdoors; using and storing paints, solvents, pesticides, and adhesives in closed containers in well-ventilated areas; using those pollutant sources in periods of low or no occupancy; and allowing time for building materials in new or remodeled areas to off-gas pollutants before occupancy.
  • Air cleaning has some limitations, but it can be a useful addition to source control and ventilation. Air filters are only effective at removing some, not all, of the pollution.
  • Education and communication are important parts of any air quality management program. When everyone associated with the building, from occupants to maintenance, fully understands the issues and communicates with each other they can work more effectively together to prevent and solve problems.