the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 06 Jul 2023
The contribution of residential wood combustion to the PM2.5 concentrations in the Helsinki Metropolitan Area
Leena Kangas
Jaakko Kukkonen
Mari Kauhaniemi
Kari Riikonen
Mikhail Sofiev
Anu Kousa
Jarkko V. Niemi
Ari Karppinen
Abstract. This article has investigated the contribution of residential wood combustion (RWC) to the fine particulate matter (PM2.5) concentrations in the Helsinki Metropolitan Area (HMA) for six years, from 2009 to 2014. We have used the PM2.5 concentrations measured at eight air quality measurement stations. The dispersion of emissions on an urban scale was evaluated with multiple source Gaussian dispersion models UDM-FMI and CAR-FMI, and on a regional scale using the chemical transport model SILAM. The overall agreement of the predicted concentrations with measurements of PM2.5 was good or fairly good for all stations and years, e.g., at the permanent residential station the daily average values of the index of agreement ranged from 0.69 to 0.81, and the fractional bias values ranged from −0.08 to 0.11, for the considered six years. Both the measured and predicted daily averaged concentrations showed increasing trends towards the lower temperature values. The highest predicted annual averaged concentrations in the region occurred in the vicinity of major roads and streets, and the suburban residential areas, to the northwest, north and northeast of the city centre. The average concentrations attributed to RWC in winter were up to 10- or 15-fold, compared to the corresponding concentrations in summer. During the considered six-yearly period, the spatially highest predicted fractions of RWC of the annual PM2.5 concentrations ranged from 12 to 14 %. In winter, the corresponding contributions ranged from 16 to 21 %. The RWC contribution was higher than the corresponding urban vehicular traffic contribution at all the residential stations during all years. The study has highlighted new research needs for the future, in particular (i) the modelling of the RWC emissions that would be explicitly based on the actual ambient temperatures, and (ii) the modelling of the impacts of the most important holiday periods on the emissions from RWC.
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Leena Kangas et al.
Status: final response (author comments only)
- RC1: 'Comment on egusphere-2023-1194', Anonymous Referee #1, 26 Sep 2023
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RC2: 'Comment on egusphere-2023-1194', Anonymous Referee #2, 17 Oct 2023
General comments
The manuscript deals with an important subject; residential wood combustion RWC induced PM pollution in urban areas. Although Helsinki has relatively clean air in general, RWC can make a substantial contribution to PM2.5 concentrations in residential areas during winter months. Given the negative health impacts of long-term exposure to PM2.5 in low concentrations, the general topic is relevant.The study builds on earlier modelling studies dealing with PM pollution from RWC in Helsinki. The earlier studies dealt mainly with annual level concentrations, while this study concentrated on validation against monitoring and temporal aspects. Therefore it shows a reasonable level of novelty.
Overall the manuscript is well and clearly written, and the results are presented in a logical manner. It presents concrete conclusions about important future research needs for temporal aspects of emission inventories. The conclusions chapter itself is longish with repetition about what has been done, and some discussion-like parts with references. Authors might want to consider moving some of these to earlier parts, or adding a Discussions chapter (if the format of the journal allows).
Specific comments
Lines 60-65:
Authors introduce reasons for increase and decrease of RWC in Europe. It is not clear whether the whole chapter is based on Viana et al. or is the vague analysis in the later part the authors’ own thinking.
The growing concern for the health impacts associated with the emissions attributed to RWC has resulted in a consideration of abatement measures for RWC.
Who has considered, and provide reference or clearly indicate if based on Viana et al.
In the long run, this might possibly result in a decreasing trend in RWC, but due to the current requirements to decrease the use of fossil energy in the EU, a significant change is not expected in the near future.
This gives an impression that the changes in the intensity of use of wood in the residential sector in the EU is mainly policy driven. Deepen the analysis and give support with references.
Lines 153-154:
It has previously been found that the contribution of other urban source categories to the PM2.5 concentrations has not been significant in this region.
Provide a reference who has found out. Often other emission sources than the ones mentioned here make a considerable contribution in urban emission inventories. For instance, construction and maintenance activities of housing and streets. To what extent e.g. construction machinery, snow clearing, motorized gardening etc. are included in the vehicular traffic category? And barbeques are mentioned later on.
Section 3.1.1:
Authors discuss factors that might affect the differences between modelled and measured concentrations. How about the uncertainties related to the spatial distribution of the emissions? How well the actual intensity of the use of RWC inside each 100m grid cell near the monitoring station is known? Although the locations of fireplaces in each house might be known from the house register, the frequency of the use might vary substantially from house to house in supplementary or recreational function. Are there any information about the variability from the surveys and has this been taken into account?
Lines 319-321:
These over-predictions at the residential sites in winter were probably caused by the assumed semi-empirical seasonal variation of RWC emissions in winter; this variation function may not have been ideal for the meteorological conditions during the considered periods.
What evidence exists that this is the case? Would it be possible to draw out data from questionnaires to support this conclusion?
Lines 454-455:
However, the recent deterioration of the economic situation and high energy prices may favour wood burning and increase emissions.
This is questionable for any mid or longer term prognosis and outdated already for the part of energy prices.
Technical corrections:
Line 431:
Repetition of clearly.
Citation: https://doi.org/10.5194/egusphere-2023-1194-RC2 - AC1: 'Comment on egusphere-2023-1194', Leena Kangas, 28 Nov 2023
Leena Kangas et al.
Leena Kangas et al.
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