Wildfire impact in high-latitude settlements

Due to the sparse population density of the high latitudes, it might be assumed that air quality would be relatively good. However, as a consequence of frequent wildfires, along with some heavily industrial regions, some settlements have similarly poor air quality to that found in large cities. Fennoscandia , as well as southern and western regions of Russia stand out as having poor air quality, while  Canada and Alaska generally have good air quality. For context, the World Health Organisation (WHO) has found that annual mean PM2.5 concentrations above 5 µg m-3 have a negative health impact, causing increased mortality and disease burden.

The WHO’s Air Quality Guideline (AQG) value of 5 µg m-3 ­is not widely achieved. In some regions, natural emissions (e.g. from plants, dust) may make the AQG impossible to achieve.

At each location we calculate the increase in annual average PM2.5 that is caused by wildfires in Arctic Council nations, on average during the 2001-2020 period.

Figure 2 shows that wildfires are causing poor air quality in settlements where it would otherwise be relatively good. This is particularly the case along the Mongolia-Russia and Mongolia-China borders, in the Sakha Republic, in central Alaska around Fairbanks, and in western Canada.

Figure 3 emphasises the regularity at which some settlements are affected by PM2.5 from Arctic Council wildfires. For parts of the high latitudes, breathing in wildfire smoke is not a rare event, but an annual occurrence that can continue for weeks or months.

In high-latitude settlements, apart from wildfire smoke, anthropogenic pollution is also a major source of air pollution. Anthropogenic air pollution can be generated by local cooking/heating/transport or can be transported into the high latitudes from further south. Anthropogenic air pollution tends to be worse in the winter, due to the combination of increased fuel usage, and more stagnant weather conditions, which allow pollutants to accumulate and have longer atmospheric lifetimes. 

The 2D colour-mapping in Figure 6 allows us to see that some settlements are affected by both summer (mostly wildfires) and winter (mostly anthropogenic) pollution (purple-maroon shades). Others are mostly affected by anthropogenic pollution (blues) or wildfires (oranges). Again, the area around the Mongolia-Russia and Mongolia-China border stands out, as it suffers with both types of pollution, as does Fairbanks, Alaska.

Figure 5  shows that some settlements have experienced increases in their annual mean PM2.5 of up to ~6 µg m-3 due to Arctic council wildfires. Since wildfires mostly occur during the summer months, the impact on PM2.5 concentrations at this time will be even larger than the annual average change.

Figure 6 shows that not only is pollution worsening overall, but the number of days affected by elevated levels of PM2.5 is increasing in some areas. Notably the Sakha Republic, Krasnoyarsk and Irkutsk regions. Parts of western Canada also show an increase, while central Alaska shows a decrease.

Methods

Example output for a settlement

We generate 20 years (2001-2020) of hourly PM2.5 concentrations. For example, the output of the model at Yakutsk at annual, daily and hourly resolution. This hourly data of the with/without Arctic Council wildfire scenarios is available for each of the over 7300 settlements.