Asthma

Dust

Health Impacts

Exposure to dust inside homes can have adverse health outcomes, such as respiratory problems, asthma, allergic reactions, and lead poisoning (if the dust contains lead). Dust comes from two sources. First, dirt and dust can be carried in from outside on shoes or blown in through windows and doors. Second, there are indoor sources of dust, particularly dust mites.

Reducing Exposure

While it is impossible to have a dust-free home, it is possible to live in a home that minimizes dust that is carried in from the outside and to avoid conditions that can promote allergens in dust.

  • Keep dust out. Because nearly two-thirds of the dust in our homes is tracked in from outdoors, one key strategy is to build and maintain homes that help occupants track off dust before it is carried inside. Simple steps such as using a mat at the entryway of a home, building steps or using grates to scrape dirt off shoes, and encouraging residents to remove shoes inside will all make a difference.
  • Using effective filters in the heating system will also reduce the allergens and contaminants entering the building or home.
  • Use materials that are easy to clean. Dust is easily removed from smooth and cleanable surfaces (smooth flooring such as wood, tile, linoleum, and vinyl) through vacuuming and mopping.
  • Use a vacuum cleaner with high filtration features (high efficiency or HEPA filter).
  • Carpets are generally more difficult to vacuum effectively than hard surfaces. But among carpets, short- and closed-loop-pile carpets (such as commercial grade carpet) are typically easier to clean than loose-pile carpets, which allow dust and dirt to fall through to the underlying material.
  • Keep dust mites under control. Dust mites contribute to dust problems, so taking precautions against them can also help reduce exposure.

More Information

http://www.getasthmahelp.org/ has many great resources to help manage asthma.

Asthma No Attacks Hotline:

1-866-NO-ATTACKS (1-866-662-8822)
Su Familia (Your Family) Helpline: 1-866-SU FAMILIA or 1-866-783-2645
The National Alliance for Hispanic Health sponsors this helpline to offer Hispanic consumers free, reliable, and confidential health information in Spanish and English and help navigate callers through the health system.

Dust Mites

Dust mites are microscopic creatures that belong to the same class (Arachnida) as spiders and ticks (they have eight legs, not six like insects). They feed primarily on dead skin cells regularly shed by humans and animals. Dust mites are found where their main food source accumulates, such as in beds and carpets.

Unlike insects such as cockroaches, mites are not capable of ingesting water; in order to obtain water, they must absorb it from the air. For this reason, they thrive in humid environments, ranging from 55% to 75% relative humidity. Ideal temperatures for dust mites are between 68º and 77º F. The growth of dust mites can vary on a seasonal basis, or from room to room within a house, depending largely on variations in relative humidity, availability of food sources, and temperature. Mites take about one month to develop from an egg into an adult and have an adult life span of about two to four months. A single adult female may lay up to 100 eggs.


Health Impacts

Mite waste products contain an allergen (a substance that causes an allergic immune reaction) that, according to the Asthma and Allergy Foundation of America, adversely affects about 20 million Americans. Sensitive individuals become exposed to this allergen when they inhale household dust, which contains dust mites and their waste products. Exposure to dust mites can trigger an attack in an asthmatic who is sensitive to the dust mite allergen. (Other asthmatics may not be affected by dust mites.) For persons allergic to dust mite allergen, exposure can cause allergic rhinitis (hay fever), which is characterized by nasal congestion, itching, and sneezing. In addition, exposure to dust mites may cause children who are predisposed to develop asthma to do so. (This predisposition is not fully understood, but appears to depend upon a combination of hereditary and environmental factors.) For more information on asthma and allergies, see Asthma, Allergies, and Respiratory Illnesses.


Common Locations

Dust mites thrive in places where dead skin cells are most likely to be found: on mattresses, pillows, bedcovers, carpets, upholstered furniture, stuffed toys, clothes, or other fabric items in the home.


Reducing Exposure

While it is impossible to have a dust-free home, it is possible to live in a home that minimizes dust that is carried in from the outside and to avoid conditions that can promote allergens in dust.

Use materials that are easy to clean. This will make it more difficult for dust mites and mold spores to thrive.

  • Dust is easily removed from smooth and cleanable surfaces (smooth flooring such as wood, tile, linoleum, and vinyl) through vacuuming and mopping.
  • Use a vacuum cleaner with high filtration features (high efficiency or HEPA filter).
  • Carpets pose several problems. They are generally more difficult to vacuum effectively than hard surfaces. Also, carpets and the sponge-like pads often installed under carpet can trap moisture once they become wet (due to a plumbing or water leak, flood, or condensation), providing a fertile setting for mold and dust mites.
  • Short- and closed-loop-pile carpets (such as commercial grade carpet) are typically easier to clean than loose-pile carpets where dust and dirt falls through to the underlying material.

Clean fabrics and other dust mite havens. The following measures will kill dust mites and reduce allergen levels.

  • Wash sheets in soapy water at 130°F every one or two weeks to kill dust mites. Take blankets to the dry cleaner, hang them outdoors once a year, or wash them frequently.
  • Cover conventional mattresses and pillows with allergen-impermeable covers or dust mite covers (micro-porous material to prevent infestation).
  • Wash soft toys and stuffed animals regularly in hot water, followed by thorough drying. The heat will kill off the mites.
  • Shampoo, steam clean, or beat non-washable rugs and carpets once a year. This removes large particles missed by the vacuum cleaner.

Reduce moisture and maintain a low relative humidity in the home. Since dust mites cannot drink water, they need to absorb it from the air, which is why they thrive in humid conditions. Reducing the humidity in your home will make it less hospitable to dust mites, which do not thrive below 60% relative humidity. It may not be feasible to completely eliminate dust mites from homes in moderately humid climates.

One way to help reduce moisture in the home is to run a bathroom and kitchen fan that exhausts to the outside after showering/bathing or cooking.

 

Ventilation and Indoor Air Quality

Proper ventilation helps improve indoor air quality. Ventilation can control indoor humidity and airborne contaminants, both of which either contribute to or act as health hazards.

Ventilation and Indoor Humidity

High indoor humidity can spur mold growth. High humidity may result from poor construction or rehabilitation, site design that does not properly manage water, and/or inadequate air exchange. A reasonable target for relative humidity is 30-60 percent. A low cost hygrometer, available at hardware stores, can be used to measure relative humidity. In cool climates, inadequate ventilation in the winter can contribute to excessive moisture and humidity because normal activities create moisture (cooking, bathing, breathing), and there is insufficient natural ventilation (opening windows) or mechanical ventilation (fans, exhaust systems) to remove the moisture. In warmer climates, the heating, ventilation, and air conditioning (HVAC) system can pull warmer, humid air inside. In this case, the ventilation system may help create indoor humidity problems unless the system also dehumidifies the air.


Airborne Contaminants


Indoor contaminants.
These include chemicals used in the construction or renovation of buildings (e.g., glues, off-gassing from carpets, emissions from particle board, cleaning compounds). In addition, appliances that burn gas can produce particulates and carbon monoxide. Incomplete combustion and poor ventilation of these appliances (cook stoves, gas furnaces, gas boilers, and gas water heaters) can contribute to indoor contaminants. Gas cook tops should be used with fans that send exhaust outside. Gas-fired heating appliances should be sealed and power-vented systems installed to remove products of incomplete combustion. Wood-burning stoves can also create particulates and must be vented outside.

Outdoor contaminants. Outdoor particulates can be drawn inside when the heating or cooling system draws air into a home. Particulates and allergens found in outdoor air can be asthma triggers. Filtering incoming air for HVAC systems effectively filters particulates. Experts recommend using filters with a MERV 6-8, but higher MERV levels trap smaller particles and generally are more appropriate for those with allergies or where the indoor environment has a high concentration of mold spores, dust particles, or other allergens.
Using Ventilation to Reduce Health Risks

Two types of ventilation can help control harmful air contaminants and humidity: spot ventilation and dilution ventilation. Spot ventilation draws air from a particular location (e.g., bathroom, kitchen) and exhausts it to the outside. Dilution ventilation address low-level contamination throughout the home.

Spot Ventilation. Exterior exhaust fans should be installed in all bathrooms and kitchens. These fans remove humidity and carbon monoxide. The most effective fans are quiet and durable. Use fans that operate at one sone or less and exhaust to the outdoors. Fans equipped with timers or de-humidistat controls are useful to ensure the fans run for a sufficient period of time. A good rule of thumb is to run a bathroom fan for about 45 minutes after a shower.

Dilution Ventilation. Dilution ventilation addresses the entire living space. Air changes (exchanging indoor air with outdoor air) and air cleaning help determine the effectiveness of dilution. Air changes result from a combination of natural ventilation (infiltration; leakage; windows) and mechanical (controlled) ventilation. Air cleaning occurs when particulates are filtered and when air is dehumidified to remove moisture. The goal is to provide sufficient changes to ensure a healthy environment. There are several types of heating and cooling systems with filtration that can be installed to accomplish this. A common element necessary in all systems is duct sealing, particularly on the return side (side drawing in the air). The Air Conditioning Contractors Association (ACCA) provides guidance on duct sealing in its Manual D: Duct Design.
HVAC Considerations

Sizing HVAC Systems

It is important not to oversize a system. Oversizing can contribute to poor air distribution and insufficient dehumidification, creating an environment that promotes mold growth. Oversized heating systems can “short cycle,” meaning that the system does not run long enough to turn the fan on for a sufficient period to distribute new air. Systems that short cycle during air conditioning will deliver cold air in short bursts but not necessarily dehumidify the air. The resulting cold, clammy environment can encourage mold growth. Some contractors oversize HVAC systems to compensate for duct leakage and to minimize complaints about heating or cooling delivery. The ACCA provides guidance on system sizing in its Manual J.

HVAC Systems Can Contribute to Air Quality Problems

HVAC systems can also exacerbate indoor air quality problems. The HVAC system may be contaminated (because of mold in duct lining or bacteria on coil or filters, for example), and the system may spread these pollutants throughout the home. Second, the HVAC duct distribution system can spread pollutants from one portion of the home to another. Regular maintenance and duct sealing can help minimize these problems.

Standards

The American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) and several states (Minnesota, Washington, and Vermont) have ventilation standards designed to ensure acceptable indoor air quality.


More Information

Air Conditioning Contractors of America

American Society of Heating and Refrigerating and Air Conditioning Engineers, Inc. (ASHRAE)

Building Science CorporationREAD THIS: Before You Ventilate

Home Energy Magazine

Minnesota – Mechanical Ventilation Systems (Minnesota’s amendments to the International Residental Code, Chapter 11)

Washington – Washington Administrative Code: Ventilation and Indoor Air Quality, 2006

General IAQ Hotline (IAQINFO): 1-800-438-4318
Sponsored by EPA, this hotline provides general information on indoor air quality and related pollutants.

Su Familia (Your Family) Helpline: 1-866-SU FAMILIA or 1-866-783-2645
The National Alliance for Hispanic Health sponsors this helpline to offer Hispanic consumers free, reliable, and confidential health information in Spanish and English and help navigate callers through the health system.

The previous comes from http://nchh.org/What-We-Do/Health-Hazards–Prevention–and-Solutions/Ventilation-and-Indoor-Air-Quality.aspx, http://nchh.org/What-We-Do/Health-Hazards–Prevention–and-Solutions/Dust.aspx, and http://nchh.org/WhatWeDo/HealthHazardsPreventionandSolutions/Insects.aspx.