Ammonia Odor 

We have recently built a home and it has a strong ammonia odor. I attribute it to either the cellulose or the sheetrock.  The house is finished and we have moved in. Should we have the air tested to make sure that it is not harmful?-Bridget, Arkansas
     In new houses ammonia can be coming from either of two places. Some latex paints when applied have high ammonia emissions. Since ammonia is rapidly released and dissipated ammonia odors associated with latex-based paints are fairly ephemeral, that is that they go away relatively quickly (lets say in about a week) Secondly many builders are increasingly using wet-spray applied cellulose insulation in the side walls of new construction. In most cases the manufacturers of this cellulose product use boric acid-polyborates as both a fire retardant and mold inhibitor for the insulation.

Some manufacturers of this product use ammonia sulfate and the ammonia can be emitted at both sensory and chemically detectable levels. Reports of ammonia odors associated with wet spray applied cellulose insulation (WSACI) are not uncommon in southern states. Unlike ammonia emissions from latex-based paints ammonia odors associated with WSACI can persistent for months or longer since the ammonia is formed from the decomposition of ammonium sulfate as environmental conditions for such decomposition become favorable.

            Documentation of this problem was been done by Barb Epstein, Industrial Hygienist( “...formerly with Air Quality Sciences, currently with Epstien Environmental Resources...” ) on investigating odor complaints in two recently constructed single-family residences in a southeast metropolitan area. In both case the buildings were WSACI insulated.

            The investigation involved an on-site visual and sensory inspection as well as air testing in both building spaces and wall cavities. In the inspection ammonia odors were noted to be present in both houses varying in intensity in one house from slight –to-moderate and in the second house from moderate-to-strong. The ammonia odor was stronger on lower as compared to upper house levels. In a second visit the odor was less intense in one house but was moderate to strong in the other.

            In the first residence 8 air samples were collected in living spaces and 10 in wall cavities. Living space and wall cavity concentrations averaged ~ 2.0 and 6.6 ppmv respectively. All living space concentrations exceeded the odor threshold of ~ 1.3 ppmv. As expected the wall cavity concentrations were significantly higher than air concentrations indicating that the wall cavities were the source of the ammonia in building spaces and that WSACI was potentially the source of ammonia.

            In the second residence 5 samples of room and cavity air were collected with average concentrations of 3.9 and 20 ppmv respectively. This house was determined to have a moderate to strong odor in an initial, and follow-up inspections.

            A second round of testing in the first house was conducted with average concentration of 0.80 ppmv suggested that the concentration decreased with time. The contractor after applying whole house dehumidification subsequently reported that the ammonia odor decreased to acceptable levels and these houses were then occupied by those who had purchased them.

You have asked whether the air in your house should be tested to make sure that it is not harmful. My response to your question can not be simply stated.

            Though there are occupational exposure guidelines for ammonia (25 ppmv 8-hour average TLV) these can not be applied to residential settings to protect building occupants. Some scientists have suggested that an appropriate indoor residential guideline exposure level be set at 1/10 the TLV. That would be 2.5 ppmv which is above the odor threshold. Another approach is the use of sensory irritation data derived from laboratory animal testing (RD 50 values) multiplied by 1/1000. Using this approach the acceptable residential exposure concentration for ammonia would be 0.3 ppmv.

            As I have previously written in postings on this website the primary health concern associated with WSACI is its propensity to allow a significant quantity of mold to grow on and in it and for this mold to significantly increase living space mold concentrations (and in so doing result in significant increases in human exposure). So in advising you or others relative to the conduct of air testing I would recommend that one also test airborne mold levels using both spore trap and culturable mold techniques and to also have a bulk sample of the WCSACI tested for mold types and concentrations by QPCR(a DNA test).

August 9, 2007