The manuscript by Li et al. investigates the roles of oxygenated organic molecules (OOMs) and sulfuric acid (H₂SO₄) in explaining atmospheric nanoparticle growth. To isolate condensational growth from coagulation, the authors developed a laminar flow reactor that enables the independent quantification of these two processes. The study combines laboratory experiments using both biogenic and anthropogenic precursors with field observations, providing a comprehensive assessment of particle growth under controlled and ambient conditions. The measurements employ three complementary mass spectrometers to maximize the detection of condensable organic vapours. My expertise lies primarily in atmospheric measurements and modelling, and therefore my comments focus on these aspects rather than on the design and characterization of the newly developed reactor.

Overall, the laboratory and field measurements are comprehensive, the methodology is robust, and the manuscript is well organized and easy to follow. The authors compare several published volatility parameterizations and demonstrate that six of the seven overestimate condensational growth. They attribute this primarily to parameterizations developed for biogenic environments that predict lower OOM volatilities, particularly under high-NOₓ conditions. I believe this is an important contribution to the field and recommend publication after addressing the following minor comments.

Minor comments

1.    A summary table comparing the seven volatility parameterizations would greatly improve readability. In particular, it would be useful to summarize the required input variables and intended application of each parameterization. Since the Zhang et al. parameterization is the only one that underestimates condensational growth, the authors should also briefly discuss the key differences that distinguish it from the others.

2.    The title, abstract, and conclusions attribute the remaining unexplained particle growth to additional processes that are not represented in the current framework. While this is certainly a plausible interpretation, the manuscript should more explicitly acknowledge other sources of uncertainty, including incomplete detection of condensable vapours by current instrumentation, uncertainties in particle size distribution and growth-rate measurements, and uncertainties within the modelling framework itself. I therefore encourage the authors to slightly soften the title and conclusions to better reflect these remaining uncertainties.

3.    The discussion would also benefit from placing the results within the context of other recent studies on condensational growth. In addition, it would be interesting to comment on the broader applicability of the conclusions beyond Lake Tai. For example, would the Zhang et al. parameterization also underestimate particle growth under low-NOₓ, biogenic environments such as Hyytiälä, Finland, or is its performance expected to be location dependent?

Technical comments

•    Line 135: "limited resolution" is missing a unit.

•    Figure 4 legend panel c: "Zhang (2025)" should be updated to "Zhang (2026)."

•    Supplementary Figure 13: "Fig." should read "Fig. S13."

The study investgates the role of OOM volatility in determining nanoparticle growth rates and demonstrates how uncertainties in volatility parameterizations can affect particle growth predictions. The findings are especially relevant for polluted environments where anthropogenic emissions and NOx chemistry strongly influence OOM composition. The manuscript makes a contribution to understanding the mechanisms controlling NPF and nanoparticle growth.  Overall, the manuscript is well written and scientifically sound. I have some minor comments and suggestions below