It is a tiny study with a lot of caveats, missing data and slightly dodgy categorisation (confounding woodburners and open fires for example). It also doesn't take into account home conditions e.g. ventilation. Their lead in study that they quote in the introduction doesn't differentiate either but does make the link with poor ventilation (which this study does not):
A survey indicated that up to 75 % of households in rural Wales use firewood (Jennifer and James, 2013), raising concerns about indoor air quality, especially in poorly ventilated homes (Khalequzzaman et al., 2011). Socioeconomic and cultural factors such as fuel poverty and traditional hearth-centred gatherings can further elevate exposure risks (Ferguson et al., 2023; Roberts, 2020).
The pilot study involved 53 children from two primary schools, with 94 % providing valid data so only 50 children. It doesn't state how many of the children were from each school, so I am going to assume 25 at each - but if it was more at the urban school then the data will be even more skewed.
The number of children with fuel burning appliances are tiny 53% of students at school B = 13 children, 21% at school A = 5 children - 18 in total out of the 50 in the study.
It also looks like there was quite a lot of data excluded but it is not made clear how many hours of home environment data was actually lost:
However, some data loss occurred, mainly due to device battery depletion or power-offs during measurements, leading to incomplete profiles. Positional errors also happened when students did not carry their backpacks while moving between microenvironments.
While the study is keen to point out the impact of woodburners and uses EPC data for woodburners in their initial mapping, they don't actually differentiate between wood burners, open fires, Rayburns, ranges etc in the data from the study which a flaw because there is a big difference in the air pollution given off by a woodburner and an open fire.
Post-survey data as shown in Table 1 indicate that one key difference between the two schools lies in the prevalence of household fuel-burning appliances. Approximately 53 % of students at School B reported having a wood burner and/or fireplace at home, compared to 21 % at School A. This suggests that indoor biomass combustion is likely a significant contributor to higher PM2.5 exposure.
This is compounded by where the sensors were places at home as well:
Which room to place sensor within the home affects pollution measurement data. According to post-survey responses, backpack placement in the home environment varied: 20 % left in the bedroom as mentioned in the instruction, 26 % left them in the kitchen, 10 % in the living room, 36 % near doors or hallways, and 8 % in other locations.
In contrast, PM2.5 levels in bedrooms and living rooms were more moderate and consistent, showing narrower distributions and lower peaks. This suggests that these spaces may offer more stable air quality conditions, potentially due to less activity, better isolation from pollution sources, or more frequent changes in air flow to refresh polluted indoor air.
This does not distinguish between School A and School B but the violin graph shows that the highest pollution levels were when backpacks were placed in the hall (suggesting they were potentially effected by the outside environment) or the kitchen (where the cooker is and again, where potentially wood or coal burning rayburns are located).
Where backpacks were placed in the living room (where woodburners are more likely to be), pollution levels were not particularly high.
So yes - you are being Very Unreasonable to suggest that people should not use woodburners based an a very small study which does not take into account the different type of woodburning appliances, household condition and ventilation, had measurements based on where children chose to leave the sensors and has a significant amount of missing data, particularly from the home environment.
If you want a true view there would need to be a study of many more households with fixed sensors in the living rooms, a non-woodburner control group in the same environment (rural / urban).