Mitigation of Suspendable Road Dust in a Subpolar, Oceanic Climate

Abstract

Tire and road wear particles (TRWP) are a significant source of atmospheric particulate matter and microplastic loading to waterways. Road wear is exacerbated in cold climate by the widespread use of studded tires. The goal of this research was to assess the anthropogenic levers for suspendable road dust generation and climatic conditions governing the environmental fate of non-exhaust particles in a wet maritime winter climate. Sensitivity analyses were performed using the NORTRIP model for the Capital region of Reykjavík, Iceland (64.1° N). Precipitation frequency (secondarily atmospheric relative humidity) governed the partitioning between atmospheric and waterborne PM10 particles (55% and 45%, respectively). Precipitation intensity, however, increased proportionally most the drainage to waterways via stormwater collection systems, albeit it only represented 5% of the total mass of dust generated in winter. A drastic reduction in the use of studded tires, from 46% to 15% during peak season, would be required to alleviate the number of ambient air quality exceedances. In order to achieve multifaceted goals of a climate resilient, resource efficient city, the most important mitigation action is to reduce overall traffic volume. Reducing traffic speed may help speed environmental outcomes.

Black Carbon along a Highway and in a Residential Neighborhood during Rush-Hour Traffic in a Cold Climate

“…The mobile data rather suggests a bi-polar relationship between BC and particulate matter (Figure 6b,c): During the winter, BC constituted ~25% of the mass of PM 2.5 , which is consistent with the BC/PM 2.5 ratio associated with fossil fuel burning in a Helsinki street canyon in winter [48]. In spring, BC represented only ~2% of the mass of PM 2.5 in accordance with local road dust, or alternatively long-transport dust, which contributed significantly to particles in the small diameter ranges [42,49].…”

“…Hourly nitrogen dioxide and particulate matter levels recorded at noontime rarely exceed 100 µg/m 3 after mid-March (Figure 3f,g). As the roads dry up, the road and tire wear particles generated from the prevalent use of studded tires in the winter can be whirled up when the cars drive on dry roads, causing particulate matter episodes [42]. Dust can also be transported from the sandy regions, some 200+ km to the east of Reykjavík, or longer-range from other continents [26].…”

Connection between the Spatial Characteristics of the Road and Railway Networks and the Air Pollution (PM10) in Urban–Rural Fringe Zones

“…According to the results of the datasets aggregated based on the main PM sources (traffic, industry, and background), the most significant and highest Spearman's rank correlation coefficient was found for the AQ monitoring points characterized as belonging to the background category, where there is no dominant PM10 source. This indicates that the effects of spatial characteristics of the road network on AQ are most pronounced in these areas, as other factors affecting AQ (e.g., land use type [20,60], meteorological characteristics such as annual wind speed [6,14,61], soil type, and traffic volume [19]) are not as dominant as in other areas.…”

“…The fact that the effect of the distance from roads on PM10 pollution could not be detected at the AQ stations where the source of pollution (industry or traffic) is precisely known suggests that other factors, such as land use, climate [61,65], topography, and soil characteristics, have a greater influence on PM10 concentration levels. This implies that future studies investigating the causes of PM10 pollution will require the inclusion of multiple datasets, such as land use type, annual wind speed, soil type, and topography datasets, and the use of multivariate models as a method of analysis may provide new insights into the problem [2,19,[66][67][68][69].…”

“…Some authors [17] suggest that the impact of the rail network on PM concentrations should be investigated. The density of the road and rail network and the distance can be used as proxies for the degree of exposure to traffic pollution in cases where direct measurement of pollutant levels is not possible [18][19][20]. The impact of the transportation infrastructure on the air quality (PM10 concentration) can depend significantly on the type of road (primary road, secondary road, motorway, etc.)…”