The article explored the relationship between VOCs and PM2.5 with abundant VOCs species observed in Zhengzhou during the COVID-19 and made recommendations for the control of VOCs source emissions.

The current discussion may not be sufficiently supportive, please add more details to each section to make the entire article more logical. Basic details regarding instrumentation and data collection are missing. The authors need to supplement materials related to the reliability of the PMF results. Furthermore, more work is needed to elucidate the relationship between VOCs and haze pollution, as well as the influencing factors. And it is suggested that model simulation on SOA formation potential be added to the manuscript.

While the theme and results of the study are interesting, I have provided a few suggestions for improvement.

Line 124-135: The authors lack more detailed descriptions of the instrumentation. What are the working procedures of the instruments? What is the time resolution of the samples? How long were the samples collected for? Where were they captured? It is recommended to include information about instrument quality control methods.

Section 2.2 PMF model

How did the authors conduct factor selection, and why did not choose the 5-factor solution, 6-factor solution, and 7-factor solution? The authors need to provide more explanations and justifications in the manuscript.

Section 3.1 Pollution characteristics

Line 194: Ensure that the font in the figures is consistently in Times New Roman. The y-axis labels do not match the legend (NO and NOx).

What does the shading in Figure 1 represent? What are Case 1, Case 2, Case 3, Case 4, and Case 5? Clear explanations need to be provided. If these cases represent haze pollution processes, how do you define your pollution processes? Please include the references you consulted.

Line 217-225: Why did you only discuss Case 1 and Case 3? Are these two periods particularly significant? Provide your reasoning.

In Figure 2, the font should be changed to Times New Roman.

In this section, you only analyzed the variations in pollutant concentrations and meteorological conditions. What is the relationship between them? Which factors are crucial causes of pollution? You have not provided analysis and explanations.

Line 222-223: “[…] Among them, Case 1 (from 222 December 5 to December 10 and […]” A closing bracket is missed.

Section 3.2 Source appointment

Line 272: ‘indicating that the measured air VOC content was influenced by both remote sources and urban area emissions’, Are you referring to all VOCs? Or specifically to m/p-xylene and ethylbenzene?

Line 271-273: Your conclusion indicates that VOCs are influenced by transport and emissions from distant regions. Can this be further substantiated through transport or other means?

Line 306: 'olefins' should be corrected to 'alkenes'.

Line 316-325: Have you performed PMF in Case 1, Case 3, and the clean days? It is recommended to check whether the results of factor analysis are consistent in different conditions (Case 1, Case 2, and clean days) and compare the results.

Section 3.2 SOAFP

In this part, only Case 1 and Case 2 processes were discussed, then leading to the conclusion that the control of PM2.5 pollution in winter should focus on controlling vehicle emissions, solvent use, and combustion. I am afraid it is not convincing enough. It is recommended to add analysis of clean days. Contrast the pollution process with the clean day.

Overall comment:

The COVID-19 lockdown measures provide a natural experiment for probing air quality changes under substantial emission reductions. Zhang et al. investigate the variations of VOCs in response to the policy-driven emission changes in Zhengzhou city of China by using online ambient measurements, and the PMF model. While this paper is within the scope of ACP, the present manuscript is limited to a cursory data analysis (simply reporting measurement results), without convincing evidence and in-depth discussion, which makes this paper unpublishable in the present form. Further, the innovation of this work is far below the standard required to be published on ACP, which is even not qualified as a measurement report. Though addressing the specific comments below may improve the paper, I don’t think these improvements could justify publication in a high-standard journal such as ACP. Concerning the major flaws and the lack of innovation, I think this paper should be rejected.

Major comments:

1) The major weakness of this work is the lack of innovation. The impacts of the Omicron outbreak on Chinese cities are already well-documented and extensive studies have been conducted to elucidate the role of the anthropogenic sector on air pollution during- and post-outbreak periods. The authors claimed that industrial and vehicular emissions are dominant sectors contributing to ambient VOC, which is quite clear in prior studies. Further, the changes in PM2.5 and VOCs in response to the lockdown are broadly consistent with previous findings in Zhengzhou (even in Chinese literature). What is the innovation of this work and what are the new findings from this work that contribute to the air quality community?

2) The usage of SOAP should be revisited. The authors should be aware that SOAP is a very simple metric that provides limited information on SOA formation potential because SOA yield for individual VOCs in China may vary significantly in other countries due to the different levels of NOx and other oxidants. SOAP is generally adopted to reflect the SOA production potential based on bottom-up emission inventory (see Wu & Xie, ES&T), rather than using short-time ambient measurements. Therefore, I doubt the conclusion driven by the simple SOAP calculation. The authors should consider using F0AM and PBM-MCM for examining SOA production changes rather than SOAP.

3) The captions of the results section are meaningless. "Pollution characteristics" and "Source appointment" is not clear to the readers and should be rewritten for clarification.

4) The writing of this paper is in need of much attention. Specifically, the writing suffers from a series of fundamental issues, including a lack of clear organization, pervasive grammatical, and stylistic errors. I suggest the authors carefully read through the manuscript and rephrase the results section. There is substantial awkward phrasing throughout the paper which is confusing and misleading to the readers.

Minor comments:

1) The SOA formation potential is called "SOAP" rather than "SOAFP". The author should correct this abbreviation.

To provide a fair assessment, I refrained from reading previous reviews of the manuscript. Zhang et al. investigated VOC emissions during winter in Zhengzhou, China, likely aiming to understand the impact of the Omicron lockdown on city pollutants. However, given the extensive documentation of air quality studies during COVID pandemic and its variants, including Omicron, the manuscript lacks novelty in this context. The discussion on source apportionment also falls short, lacking depth and quantitative analysis. Overall, the manuscript does not meet the standards for publication in ACP. I recommend the authors revise the manuscript, enhance data analysis and interpretation, present their findings in a more scientifically rigorous manner, and plan to resubmit as a new submission.

Some of my major concerns are as below:

1. The manuscript lacks analysis of measurements during or post-Omicron period to provide relevant insights for policy and management. Authors have broadly compared two pollution cases with a clean day during the sampling period. Even in this regard, the poor labeling technique of Figure 1, makes it very confusing what are Cases 1 through 5. Discussions for Cases 2 and 4 are missing. I feel that the title is misleading as the data has not been leveraged to present relevant results related to the Omicron period and policy relevance.
2. In the source apportionment section, the authors seem to have limited knowledge of using the VOC ratios. The results presented are very vague and do not seem to add any quantitative information.
3. The PMF source apportionment is weak, lacking statistical analysis and error estimation. There is no statistical analysis that supports why 5 factor was the best solution. The use of median value to replace missing values is not a justifiable way to treat the data, if the authors think so then needs to be discussed. Authors should examine at least 100 base runs with different seed numbers to find the best solution. Authors should discuss uncertainty and error estimations, and rotation ambiguity analysis.  
4. While analyzing PMF factors, authors should use the time series trend, diurnal variations, use of wind speed and direction for identifying possible source sectors, and comparison with other inorganic tracers like trace gases to parameterize the PMF factors. Without some of these analyses, naming the factors just using the VOC profile may be inaccurate as there can be several sources for an individual VOC.
5. The authors should analyze differences in PMF factors/source profiles during and post-Omicron lockdown days and between high pollution and clean days.
6. The use of short-term measurements for SOA formation potential may not provide quantitative results. Authors should acknowledge such limitations. The comparison between Case 1 and 2 SOA formation potential is unclear regarding what information provided by the authors is useful.

Minor comment:

1. Methodology details for VOC, trace gas, PM, and meteorological measurements, including instrumentation techniques, calibration methods, data curation, and validation, should be provided.
2. English editing is necessary to improve the manuscript's readability and clarity.