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Abstract Ammonia control has received increasing attention as a measure to decrease particulate concentrations. Modeling analysis of observation data from central China over the period of September 2015 to August 2016 shows clear asymmetric responses of particulate pH and mass to ammonia emissions. With a change of ±80% of NH_x(NH₃+ NH₄⁺), the corresponding ΔpH are +0.5 and −3.0, respectively, and the corresponding particulate NH₄⁺changes are +2.62% and −61.8%, respectively. This asymmetry implies that there is a Critical Total Ammonia Concentration, above which particulate pH and mass are insensitive to ammonia control. Analysis of the observation data suggests that the Critical Total Ammonia Concentration is −25%. The estimated cost for an NH_xreduction of 25% is $140 – 320 million for Hubei province, which is the initial cost barrier before ammonia control can effectively affect particulate pH and mass in central China. This cost barrier will increase as NO_xand SO₂emissions decrease.