The relationship between airborne acidity and ammonia in indoor environments.

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.