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 Recommended Indoor Temperature Relative Humidity Temperature Outdoors Indoor Relative Humidity +20o F. 35% +10o F. 30% 0o F. 25% -10o F. 20% -20o F. 15% Source: Anne Field, Extension Specialist, Emeritus, with reference from the Association for Home Appliance Manufacturers (aham.org). How to Identify the Cause of a Mold and Mildew Problem Mold and mildew are commonly found on the exterior wall surfaces of corner rooms in heating climate locations. An exposed corner room is likely to be significantly colder than adjoining rooms, so that it has a higher relative humidity (RH) than other rooms at the same water vapor pressure. If mold and mildew growth are found in a corner room, then relative humidity next to the room surfaces is above 70%. However, is the RH above 70% at the surfaces because the room is too cold or because there is too much moisture present (high water vapor pressure)? The amount of moisture in the room can be estimated by measuring both temperature and RH at the same location and at the same time. Suppose there are two cases. In the first case, assume that the RH is 30% and the temperature is 70oF in the middle of the room. The low RH at that temperature indicates that the water vapor pressure (or absolute humidity) is low. The high surface RH is probably due to room surfaces that are too cold. Temperature is the dominating factor, and control strategies should involve increasing the temperature at cold room surfaces. In the second case, assume that the RH is 50% and the temperature is 70oF in the middle of the room. The higher RH at that temperature indicates that the water vapor pressure is high and there is a relatively large amount of moisture in the air. The high surface RH is probably due to air that is too moist. Humidity is the dominating factor, and control strategies should involve decreasing the moisture content of the indoor air. Should You Have the Air Ducts in Your Home Cleaned? - excerpt on duct cleaning and mold follows, please review the entire document for additional information on duct cleaning and mold. You should consider having the air ducts in your home cleaned if: There is substantial visible mold growth inside hard surface (e.g., sheet metal) ducts or on other components of your heating and cooling system. There are several important points to understand concerning mold detection in heating and cooling systems: •Many sections of your heating and cooling system may not be accessible for a visible inspection, so ask the service provider to show you any mold they say exists. •You should be aware that although a substance may look like mold, a positive determination of whether it is mold or not can be made only by an expert and may require laboratory analysis for final confirmation. For about $50, some microbiology laboratories can tell you whether a sample sent to them on a clear strip of sticky household tape is mold or simply a substance that resembles it. •If you have insulated air ducts and the insulation gets wet or moldy it cannot be effectively cleaned and should be removed and replaced. •If the conditions causing the mold growth in the first place are not corrected, mold growth will recur. Additional Resource •U.S. Dept. of Agriculture, Food Safety and Inspection Service fact sheet - Safe Food Handling- Molds on Foods: Are They Dangerous? September 2005 •A Brief Guide to Mold in the Workplace, U.S. Dept. of Labor, Occupational, Safety and Health Administration, Safety and Health Bulletin 03-10-10 Top of page Indoor Air Regulations and Mold Standards or Threshold Limit Values (TLVs) for airborne concentrations of mold, or mold spores, have not been set. Currently, there are no EPA regulations or standards for airborne mold contaminants. Top of page Large Buildings and Mold EPA has a number of resources available, you can start with the Indoor Air Quality Building Evaluation and Assessment Model (I-BEAM). I-BEAM updates and expands EPAs existing Building Air Quality guidance and is designed to be comprehensive state-of-the-art guidance for managing IAQ in commercial buildings. This guidance was designed to be used by building professionals and others interested in indoor air quality in commercial buildings. I-BEAM contains text, animation/visual, and interactive/calculation components that can be used to perform a number of diverse tasks. See epa.gov/iaq/largebldgs/i-beam/index.html. See also Building Air Quality: A Guide for Building Owners and Facility Managers. Excerpt from the Building Air Quality: A Guide for Building Owners and Facility Managers, Appendix C - Moisture, Mold and Mildew: How to Identify the Cause of a Mold and Mildew Problem. Mold and mildew are commonly found on the exterior wall surfaces of corner rooms in heating climate locations. An exposed corner room is likely to be significantly colder than adjoining rooms, so that it has a higher relative humidity (RH) than other rooms at the same water vapor pressure. If mold and mildew growth are found in a corner room, then relative humidity next to the room surfaces is above 70%. However, is the RH above 70% at the surfaces because the room is too cold or because there is too much moisture present (high water vapor pressure)? The amount of moisture in the room can be estimated by measuring both temperature and RH at the same location and at the same time. Suppose there are two cases. In the first case, assume that the RH is 30% and the temperature is 70oF in the middle of the room. The low RH at that temperature indicates that the water vapor pressure (or absolute humidity) is low. The high surface RH is probably due to room surfaces that are too cold. Temperature is the dominating factor, and control strategies should involve increasing the temperature at cold room surfaces. In the second case, assume that the RH is 50% and the temperature is 70oF in the middle of the room. The higher RH at that temperature indicates that the water vapor pressure is high and there is a relatively large amount of moisture in the air. The high surface RH is probably due to air that is too moist. Humidity is the dominating factor, and control strategies should involve decreasing the moisture content of the indoor air. Top of page Schools and Mold and Indoor Air Quality The Agencys premier resource on this issue is the Indoor Air Quality Tools for Schools kit. Our schools-related resources on the web start at: epa.gov/iaq/schools. The asthma companion piece for the IAQ Tools for Schools Action kit, is Managing Asthma in the School Environment - epa.gov/iaq/schools/managingasthma.html. This publication has a section entitled Clean Up Mold and Moisture Control: An excerpt follows: Common Moisture Sources Found in Schools Moisture problems in school buildings can be caused by a variety of conditions, including roof and plumbing leaks, condensation, and excess humidity. Some moisture problems in schools have been linked to changes in building construction practices during the past twenty to thirty years. These changes have resulted in more tightly sealed buildings that may not allow moisture to escape easily. Moisture problems in schools are also associated with delayed maintenance or insufficient maintenance, due to budget and other constraints. Temporary structures in schools, such as trailers and portable classrooms, have frequently been associated with moisture and mold problems. Suggestions for Reducing Mold Growth in Schools Reduce Indoor Humidity •Vent showers and other moisture-generating sources to the outside. •Control humidity levels and dampness by using air conditioners and de-humidifiers. •Provide adequate ventilation to maintain indoor humidity levels between 30-60%. •Use exhaust fans whenever cooking, dishwashing, and cleaning in food service areas. Inspect the building for signs of mold, moisture, leaks, or spills •Check for moldy odors. •Look for water stains or discoloration on the ceiling, walls, floors, and window sills. •Look around and under sinks for standing water, water stains, or mold. •Inspect bathrooms for standing water, water stains, or mold. •Do not let water stand in air conditioning or refrigerator drip pans. Respond promptly when you see signs of moisture and/or mold, or when leaks or spills occur •Clean and dry any damp or wet building materials and furnishings within 24-48 hours of occurrence to prevent mold growth. •Fix the source of the water problem or leak to prevent mold growth. •Clean mold off hard surfaces with water and detergent, and dry completely. •Absorbent materials such as ceiling tiles, that are moldy, may need to be replaced. •Check the mechanical room and roof for unsanitary conditions, leaks, or spills. Prevent moisture condensation •Reduce the potential for condensation on cold surfaces (i.e., windows, piping, exterior walls, roof, or floors) by adding insulation. Floor and carpet cleaning •Remove spots and stains immediately, using the flooring manufacturer’s recommended techniques. •Use care to prevent excess moisture or cleaning residue accumulation and ensure that cleaned areas are dried quickly. •In areas where there is a perpetual moisture problem, do not install carpeting (i.e., by drinking fountains, by classroom sinks, or on concrete floors with leaks or frequent condensation). Top of page Mold Publications The publication, A Brief Guide to Mold, Moisture, and Your Home, is available in HTML and PDF (PDF, 20 pp., 278 K, about PDF) •[EPA 402-K-02-003] reprinted September 2010 Una Breve Guía para el Moho, la Humedad y su Hogar está disponible en el formato PDF (PDF, 20 pp., 796 K). •[Documento de la agencia EPA número 402-K-03-008] The publication, Mold Remediation in Schools and Commercial Buildings, is available in HTML and PDF (PDF, 56 pp., 1.6 M) •[EPA 402-K-01-001] reprinted September 2008 Top of page Other Resources WHO Guidelines for Indoor Air Quality: Dampness and Mould (PDF) (248 pp., 2.65 M) World Health Organization, 2009 EPAs Office of Research and Development, National Exposure Research Lab, Microbiological and Chemical Exposure Assessment Division, Microbial Exposure Research Branch: Geographic Distribution of Environmental Relative Moldiness Index (ERMI) in U.S. Homes Top of page How to Order Publications You can order Indoor Air Quality publications from EPAs National Service Center for Environmental Publications (NSCEP): U.S. Environmental Protection Agency National Service Center for Environmental Publications (NSCEP) Website: epa.gov/nscep Phone: 1-800-490-9198 Fax: (301) 604-3408 Email: nscep@bps-lmit NSCEP operates a Toll-free phone service for EPA Publication Assistance with live customer service representative assistance Monday through Friday from 9:00am-5:30pm eastern time. Voice Mail is available after operating hours. You can fax or e-mail your publication requests. For technical assistance with NSCEP web pages, write to: [email protected]. Please use the EPA Document Number when ordering from NSCEP. Top of page Mold Basics Mold Cleanup Cleanup Guidelines Hidden Mold Mold Image Library Introduction to Mold Mold Course Prevention and Control Tips What to Wear When Cleaning Mold Flood Cleanup Español Indoor Air Quality Area NavigationMold & Moisture Home -------------------------------------------------------------------------------- Basic InformationWhere You LiveFrequent QuestionsPublicationsMold CourseGlossary of TermsRelated LinksFlood CleanupNatural EmergenciesEl medio ambiente y su salud: Moho
Posted on: Tue, 12 Nov 2013 12:51:46 +0000
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