Forty seven residential buildings were monitored for indoor acid aerosol, nitric acid and ammonia concentrations over a summer in State College, Pennsylvania. Questionnaires were also distributed for information on occupant behaviour. The paper discusses the relationship between ammonia and concentrations of aerosol strong acidity and HNO3 in the buildings. The indoor outdoor relationship was also analysed. High indoor NH3 levels were found and low acid levels. Mass balance models that included an NH3 neutralisation term were found to predict indoor acid concentrations reasonably well.
Proposes a method for measuring the rate of air change in factories using ammonia as a tracer gas and measuring its rate of decay by a colorimetric method. The advantage is that extremely small quantities can be detected. The method is cheap, easy to use, reasonably accurate and unobjectionable to the occupants.
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