Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Civil and Environmental Engineering

Committee Chair(s)

Randal Martin


Randal Martin


Laurie McNeill


Patrick Singleton


This study aims to quantify ammonia (NH3) emission rates from the on-road gasoline and diesel motor vehicles fleet of the Wasatch Front, Utah. For this purpose, a portable Pollution Emissions Monitoring System (PEMS) was used to estimate NH3 emission rates from a representative fleet of 53 in-use light-duty (LD) gasoline and diesel vehicles over a total of 166 on-road Real Driving Emissions (RDE) tests. The post-catalyst concentrations of NH3 precursors, nitrogen oxides (NOx) and carbon monoxide (CO) were also measured. The outcomes of this study showed that a motor vehicle in the Wasatch Front would emit 55.6 mg for every traveled mile. The average NH3 emission rates of gasoline and diesel motor vehicles were 62 and 10.7 mg/mile, respectively. Together, the on-road gasoline and diesel motor vehicles in the Wasatch Front produce an estimated 1,496.5 metric tons of NH3 every year. The study also showed that vehicle characteristics (model year, mileage reading, engine displacement and number of cylinders), the concentration of NH3 precursors (carbon monoxide and oxides of nitrogen) and driving conditions impact NH3 emission rates from the on-road vehicles fleet. Thus, limiting the number of old on-road vehicles with aged catalytic converters by replacing them with newer vehicles or repairing their exhaust control devices would significantly reduce NH3 emission rates from motor vehicles fleet.