The Role of Ammonia Measurements in National Routine Ambient Air Monitoring Networks

The role of ammonia in air program management is gaining more attention as secondarily formed particulate matter is now a principal focus in the air quality agenda. Ammonia also cuts across environmental media with impacts related to watershed eutrophication and neutralization that demand comprehensive integration across media and effects pathways when considering ammonia mitigation strategies. Although the fate and transport processes governing ammonia through the atmosphere are relatively well understood, our ability to characterize ammonia emission processes and ambient air concentrations are compromised given: 1) the pervasiveness and highly variable nature of several agricultural and industrial emission sources; 2) complex interactions between ammonia gas and nearby landscape (which can either be a source or sink to uptake ammonia and re-release some or all of it at a later time); and 3) by the thermodynamic properties of ammonia which partitions across particle and gaseous phases at typical environmental conditions. Collectively, the relative importance of ammonia in environmental management practice combined with characterization difficulties pose substantial questions regarding a national approach to more routine monitoring of airborne ammonia. This presentation discusses design considerations accommodating ammonia measurements in the national air monitoring strategy.