Potential Health Impacts from a Wildfire Smoke Plume over Region Jämtland Härjedalen, Sweden
, Joakim Langner 2 and Bertil Forsberg 1,*Round 1
Reviewer 1 Report
Overall comments:
This manuscript presents a modeling-based scenario analysis to estimate the potential health impacts of wildfire smoke exposure in the Jämtland Härjedalen region of Sweden. The authors use the MATCH chemistry transport model to simulate PM2.5 concentrations under two scenarios where major wildfire plumes affect the city of Östersund. They then combine the modeled PM2.5 levels with population data and exposure-response functions to quantify excess cases of mortality, hospital admissions, and emergency visits.
The topic is relevant and timely given the increasing threat of wildfires at northern latitudes due to climate change. The manuscript is well-written overall. The methods and scenarios are clearly described. The discussion provides good context about wildfire smoke exposure in this region and uncertainties in the health impact analysis.
However, there are some major concerns regarding the exposure modeling methodology that need to be addressed:
Major concerns:
- No evaluation of the modeled PM2.5 concentrations against measurements is presented. Some discussion of model performance and validation is needed, even if only measurements from nearby regions are available for comparison. Without this, the validity of the exposure estimates is highly uncertain.
- Shifting plumes horizontally to construct scenarios can introduce significant errors. Plume transport and dispersion are dependent on meteorology and topography. An atmospheric chemistry-transport model should be run with emissions in the actual locations to capture this properly.
- Were any sensitivity analyses conducted related to model parameters and inputs? Uncertainties in the exposure modeling need to be better characterized.
Minor comments:
- The discussion could benefit from more comparisons to other similar modeling studies of wildfire smoke impacts.
- The conclusions may overstate public health implications given the minor impacts estimated. It may be necessary to better highlight uncertainties.
Author Response
Major concerns:
- No evaluation of the modeled PM2.5 concentrations against measurements is presented. Some discussion of model performance and validation is needed, even if only measurements from nearby regions are available for comparison. Without this, the validity of the exposure estimates is highly uncertain.
Response: We have added comparisons of PM2.5 to observations from one air quality station in the region and to visibility observations at 11 meteorological stations in the region in a supplement material, along with a discussion of these comparisons in the methods section of the paper. In the supplement material we have also added figures showing diurnal maximum distributions of PM2.5 over the most affected region and time period to give the reader a better understanding of the simulation results.
- Shifting plumes horizontally to construct scenarios can introduce significant errors. Plume transport and dispersion are dependent on meteorology and topography. An atmospheric chemistry-transport model should be run with emissions in the actual locations to capture this properly.
Response: In the methods section we have clarified that it is the population distribution rather than the simulated plumes that are shifted in the two scenarios. We discuss the fact that forest coverage in Sweden is substantial and that it is therefore not unreasonable to assume a scenario where wildfire smoke hits a larger population centre more directly than the case was in 2018.
- Were any sensitivity analyses conducted related to model parameters and inputs? Uncertainties in the exposure modeling need to be better characterized.
Response: We have expanded the discussion of uncertainties in the exposure modeling in the Discussion section focusing on uncertainties in the fire emission data.
Minor comments:
- The discussion could benefit from more comparisons to other similar modeling studies of wildfire smoke impacts.
Response: This has now been added.
- The conclusions may overstate public health implications given the minor impacts estimated. It may be necessary to better highlight uncertainties.
Response: We agree and modified this statement.
Reviewer 2 Report
Interest to the readers of this manuscript is high. However, I have some below questions.
1. Is there any innovation of study methods using in the manuscript?
2.Is there some new opinions compared to before?
3. Results shown in manuscript are not enough. I suggest show more.
Author Response
Interest to the readers of this manuscript is high. However, I have some below questions.
- Is there any innovation of study methods using in the manuscript?
Response: Yes, we found a way to construct a “worst case scenario” for this type of region with few large urbanizations surrounded by large forests.
- Is there some new opinions compared to before?
Response: Since there are no similar previous calculations for Scandinavia there is no way to compare.
- Results shown in manuscript are not enough. I suggest show more.
Response: We have added comparisons of PM2.5 to observations from one air quality station in the region and to visibility at 11 meteorological stations in the region in a supplement along with a discussion of these comparisons in the methods section of the paper. In a supplement material we have also added figures showing diurnal maximum distributions of PM2.5 over the most affected region and time period to give the reader a better understanding of the simulation results. In the paper we have added Figure 2 to illustrate the scenarios better.
Reviewer 3 Report
The authors conducted set of simulations using MATCH air quality model to quantify the potential health impacts due to wildfire smoke exposure in municipalities of Sweden. The study seems to have several flaws which needs to addressed before it is considered for publication.
Major comments
1. There is no model evaluation. Is there no relevant variable that can be evaluated with atleast satellite data? Doesn’t MATCH provide Aerosol optical depth (AOD) in its output? Without any evaluation, there is less confidence on the model output for chemistry variables, let alone health impacts.
2. The scenarios considered in the study seem to be highly unrealistic and unconvincing. The authors have attempted to shift the modeled PM2.5 fields/plumes by more than 100 km in both scenarios. Kindly defend these scenarios with proper reasoning otherwise they seem like a major weakness of this study. Also there should be figures showing actual modeled plume behavior/PM2.5 distribution and the location of Sveg and Ostersund (in figure 1) so that readers can understand better.
Minor comments
Line 65 – Reference is repeated.
Line 82-83 - Elaborate more on what you mean by less favorable meteorological conditions.
Line 94 – as part ‘of’ the
Line 99 – check this line once
Line 114 – 0.1o x 0.1o translates to ~ 12 km x 12 km. Why is it 6 by 12 km?
Line 141 – Rephrase this line.
Line 146 - ‘for every respective year’. What is the meaning of this?
Line 165 – What is the resolution of population data?
Line 186 – What is Y0/100 000?
English should be improved in some places.
Author Response
Please see the attachment
Author Response File: 
Author Response.pdf
Round 2
Reviewer 1 Report
Overall the authors were responsive to the critiques, and the revised paper is substantially improved.
Reviewer 3 Report
No more comments
