In this manuscript, Afroz et al. fill the gap in the current understanding of Canadian wildfire boreal surface fuels and provide useful implications for evaluating current Canadian wildfire emission inventories, which underestimate the Canadian boreal peat EF. This manuscript also takes advantage of two Picarro measurements to quantify the total NMOC and provides promising insight by using fuel moisture to explain the variability in VOC emissions. However, several aspects require further clarification. In particular, the manuscript needs better justification for the duct-flow-based EF calculation method relative to the more commonly used carbon mass balance approach, and for missing low-molecular-weight VOCs and gas-particle partitioning. In addition, some comparisons between laboratory and aircraft-based measurements would benefit from a more cautious interpretation that accounts for differences in fuel type, combustion conditions, plume age, dilution, chemical processing, and sampling platform.

My major comments are below:

1. Many of the studies used for comparison (like Koss et al., 2018; Permar et al., 2021) use the carbon-mass balance method for calculating EF. The manuscript should clarify the advantages and limitations of this method relative to the carbon-mass balance method. Because this study directly relies on measured duct flow, it would also be useful to describe whether and how the hood/duct system was validated to ensure complete smoke capture.
2. The emission factor calculation equation is defined for mixing ratio (ppb); then it should be converted to 10^-9 mol/mol. The authors should check the equation.
3. For the 46 VOC EFs, it would be helpful to compare the full set of reported VOCs with previous VOCs’ full mass spectrum biomass-burning studies. This comparison would also help clarify the origin of the “missing VOC” percentage discussed for Figure 3(c) and Lines 345–350. Important low-molecular-weight compounds, such as methanol and formaldehyde, were not quantified in this study, although these species have been shown in previous laboratory and wildfire studies to contribute substantially to total VOC mass. The manuscript would benefit from a simple quantitative comparison or discussion of the expected contribution of these missing compounds to better place the reported VOC mass fraction in context.
4. For Figure S7(c). GR (dry) and MU (dry) correlation is poor (R² =0.31). Additional explanation would be helpful. And are there any factors that affect it? Even for GR (dry, 20% moisture) and MU (dry, 4% moisture), they are considered “Dry”. Absolute fuel moisture can be a factor impacting the EF of VOCs beyond the fuel itself. It is helpful to clarify it.
5. Regarding the “Mag-Mode" the manuscript described in the supplementary material, the manuscript should explain more clearly how this bias was corrected. Are there any high m/z species that are underestimated?
6. Lines 270–275, gas and aerosol partitioning can play an important role in BB emission (May et al., 2013; Pagonis et al., 2023). This topic needs to be included in the discussion.

Detailed comments are:

Line 319, acrylic acid should be C₃H₄O₂.

Line 330-334, guaiacol is considered a low-temperature pyrolysis indicator in a PMF analysis. Even high- or low-temperature pyrolysis does not correspond exactly to the commonly used “flaming” or “smoldering”, but it still can be helpful to add here.

Line 372, can you explain why MU has poor correlations?

Line 391, most of the quantified VOC. How many? Can you present XX out of 46 or as a percentage?

Line 560, the higher EFs of HONO, NO, VOCs, and other species observed in lab studies compared with aircraft measurements cannot be explained simply by the difference between fresh and aged smoke. Other factors, such as differences in fuel type, peat contribution, fuel nitrogen content, combustion conditions, and sampling platform, can also affect this. For example, peat fuels can emit more N-containing species, while aircraft measurements of aged plumes may be affected by chemical processing, gas-particle partitioning, dilution, and possible loss or evaporation of SVOCs, IVOCs, etc.

Citation:

https://pubs.acs.org/doi/abs/10.1021/acs.est.3c05017

www.atmos-chem-phys.net/14/199/2014/

10.5194/acp-11-12197-2011

https://doi.org/10.1002/jgrd.50828

This manuscript presents a study investigating the trace gas emissions from controlled laboratory burning of Canadian boreal forest fuels. The topic of this study falls within the scope of the journal Atmospheric Chemistry and Physics. This manuscript is generally laid out well and shows its academic value. This manuscript is recommended to be published after making some minor technical changes.

Line 134: Please provide the full form of PFA before using the acronym by itself.

Line 141: Please define m/z. The ratio might be common for people using mass spectrometers but should still be mentioned first.

Line 162: Please provide the full form of UHP before using the acronym by itself. While it might be obvious for people using compressed gases in cylinders, it should still be provided first. Also please provide the percentage of purity for UHP in this case.

Line 179: Please provide the definition of E/N.

Line 182: Please spell out what PEEK stands for first before using the acronym by itself, even though this type of tubing might be very common in the field.

Line 537: What is the relation between NMOG and NMOC_G?

Figure 7: Please provide a version in the supplementary information with error bars.