Current re
gulation aimed at reducin
g inor
ganic atmosphericfine particulate matter (PM
2.5) is focused on reductionsin sulfur dioxide (SO
2) and oxides of nitro
gen (NO
x ![](/ima<font color=)
ges/entities/equiv.
gif"> NO+ NO
2); however, controls on these pollutants are likely toincrease in cost and decrease in effectiveness in thefuture. A supplementary strate
gy is reduction in ammonia(NH
3) emissions, yet an evaluation of controls on ammoniahas been limited by uncertainties in emission levels and inthe cost of control technolo
gies. We use state of thescience emission inventories, an emission-based re
gionalair quality model, and an explicit treatment of uncertaintyto estimate the cost-effectiveness and uncertainty of ammoniaemission reductions on inor
ganic particulate matter inthe Eastern United States. Since a paucity of dataon a
gricultural operations precludes a direct calculationof the costs of ammonia control, we calculate the "ammoniasavin
gs potential", defined as the minimum cost ofapplyin
g SO
2 and NO
x emission controls in order to achievethe same reduction in ambient inor
ganic PM
2.5 concentrationas obtained from a 1 ton decrease in ammonia emissions.Usin
g 250 scenarios of NH
3, SO
2, and NO
x emission reductions,we calculate the least-cost SO
2 and NO
x control scenariosthat achieve the same reduction in ambient inor
ganicPM
2.5 concentration as a decrease in ammonia emissions.We find that the lower-bound ammonia savin
gs potentialin the winter is $8,000 per ton NH
3; therefore, many currentlyavailable ammonia control technolo
gies are cost-effective compared to current controls on SO
2 and NO
xsources. Lar
ger reductions in winter inor
ganic particulatematter are available at lower cost throu
gh controls onammonia emissions.