This study investigates aerosol “sensitivity regimes” to explore the effectiveness of abating gaseous precursors to mitigate aerosols over the Indo-Gangetic Plain (IGP). A new mechanistic insight is proposed by integrating ISORROPIA-II thermodynamical model with high-resolution simultaneous measurements of precursor gases (HCl, HNO₃, and NH₃) and inorganic constituents of PM₁ and PM_2.5, monitored for the first time in India using MARGA-2S instrument. The estimated aerosol acidity (pH) of PM₁ and PM_2.5 was 4.49±0.53 and 4.58±0.48, respectively. The sensitivity of phase-partitioning (ε) of Cl^-, NO₃^-, and NH₄⁺ to pH, ALWC, HCl, HNO₃, and NH₃ showed that fine aerosols fall in the ”HCl and HNO₃ sensitive regime”, emphasizing that HCl and HNO₃ reductions would be the most effective pathway to reduce aerosols in NH₃-rich IGP. Since existing mitigation strategies over IGP are random and ineffective, this novel insight is the first step in providing a thermodynamically consistent “roadmap” to mitigate aerosols effectively.