A recent study by the California Air Resources Board (ARB) concluded that indoor concentrations of formaldehyde in recently built homes often exceeds exposure guidelines for indoor air contaminants due to the many indoor air sources for formaldehyde. There are other indoor air contaminants that also exceed exposure guidelines and researchers are recommending mechanical air ventilation systems be included in new home construction for purposes of controlling indoor air contaminants and improving air quality.
It has been proven that new homes are being built relatively airtight which is intended to reduce heating and cooling loss but have the unintended consequence of trapping airborne contaminants and VOC's (Volatile Organic Chemicals, like formaldehyde) inside the home.
It has been a concern of the both the EPA and CDC as "tight" homes do not have enough air exchanges through "natural" ventilation and as a result the contaminants become trapped inside the home leading to the exacerbation of respiratory ailments and other illnesses. Their recommendation is the same as ARB, installing a mechanical ventilation unit to provide a continuous supply of outdoor air which improves the air exchange rate and reduces indoor air contaminant levels.
In homes with basements and/or crawl spaces, these mechanical ventilation units should be installed in the lowest area of the home as the contaminated air flows to the lowest level in the home and these units can then remove and vent this "bad" air to the outside. In homes built on slabs, similar mechanical units can be used and there are other more sophisticate whole home systems that can be considered.
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