Road dust from pavement wear and traction sanding

Vehicles affect the concentrations of ambient airborne particles through exhaust emissions, but particles are also formed in the mechanical processes in the tire-road interface, brakes, and engine. Particles deposited on or in the vicinity of the road may be re-entrained, or resuspended, into air through vehicle-induced turbulence and shearing stress of the tires. A commonly used term for these particles is ?road dust?. The processes affecting road dust emissions are complex and currently not well known.Road dust has been acknowledged as a dominant source of PM10 especially during spring in the sub-arctic urban areas, e.g. in Scandinavia, Finland, North America and Japan. The high proportion of road dust in sub-arctic regions of the world has been linked to the snowy winter conditions that make it necessary to use traction control methods. Traction control methods include dispersion of traction sand, melting of ice with brine solutions, and equipping the tires with either metal studs (studded winter tires), snow chains, or special tire design (friction tires). Several of these methods enhance the formation of mineral particles from pavement wear and/or from traction sand that accumulate in the road environment during winter. When snow and ice melt and surfaces dry out, traffic-induced turbulence makes some of the particles airborne.A general aim of this study was to study processes and factors underlying and affecting the formation and emissions of road dust from paved road surfaces. Special emphasis was placed on studying particle formation and sources during tire road interaction, especially when different applications of traction control, namely traction sanding and/or winter tires were in use. Respirable particles with aerodynamic diameter below 10 micrometers (PM10) have been the main concern, but other size ranges and particle size distributions were also studied. The following specific research questions were addressed: i) How do traction sanding and physical properties of the traction sand aggregate affect formation of road dust? ii) How do studded tires affect the formation of road dust when compared with friction tires? iii) What are the composition and sources of airborne road dust in a road simulator and during a springtime road dust episode in Finland? iv) What is the size distribution of abrasion particles from tire-road interaction? The studies were conducted both in a road simulator and in field conditions.The test results from the road simulator showed that traction sanding increased road dust emissions, and that the effect became more dominant with increasing sand load. A high percentage of fine-grained anti-skid aggregate of overall grading increased the PM10 concentrations. Anti-skid aggregate with poor resistance to fragmentation resulted in higher PM levels compared with the other aggregates, and the effect became more significant with higher aggregate loads. Glaciofluvial aggregates tended to cause higher particle concentrations than crushed rocks with good fragmentation resistance. Comparison of tire types showed that studded tires result in higher formation of PM emissions compared with friction tires. The same trend between the tires was present in the tests with and without anti-skid aggregate. This finding applies to test conditions of the road simulator with negligible resuspension.Source and composition analysis showed that the particles in the road simulator were mainly minerals and originated from both traction sand and pavement aggregates. A clear contribution of particles from anti-skid aggregate to ambient PM and dust deposition was also observed in urban conditions. The road simulator results showed that the interaction between tires, anti-skid aggregate and road surface is important in dust production and the relative contributions of these sources depend on their properties. Traction sand grains are fragmented into smaller particles under the tires, but they also wear the pavement aggregate. Therefore particles from both aggregates are observed. The mass size distribution of traction sand and pavement wear particles was mainly coarse, but fine and submicron particles were also present

Emissions of Black Carbon and Methane in Finland: 2015 National Submission to the Arctic Council

The Arctic air continues to warm at twice the global average rate. Loss of Arctic snow/ice cover and thawing of permafrost accelerate warming on a global basis, and melting of land-based ice contributes to global sealevel rise. In other words the rapid warming of the Arctic has profound consequences not only for the Arctic region but also worldwide. What happens in the Arctic doesn’t stay in the Arctic. To slow the pace of warming over the next two to three decades – globally and in the Arctic – reducing emissions of short-lived climate pollutants such as black carbon and methane is essential, along with action to reduce CO2, emissions. Not only do these short-lived substances persist in the atmosphere for far shorter periods than CO2, but they also trap more heat on a per-unit basis. In addition, black carbon that falls on Arctic ice or snow reduces reflectivity and increases heat absorption, further accelerating melting and warming. In April 2015 the Ministers of the Arctic Council adopted a Framework for Enhanced Action to Reduce Black Carbon and Methane Emissions. The Framework lays out a common vision for enhanced action to accelerate the decline of black carbon emissions and significantly reduce methane emissions. As an important step towards achieving this vision the Framework provides an “ambitious, aspirational and quantitative collective goal on black carbon” would be adopted at the 2017 ministerial. An Expert Group, chaired by the Arctic state holding the Council chair for that two-year cycle, is tasked to periodically assess progress of the implementation of the Framework, and to inform policy makers from Arctic states and for participating Arctic Council Observer states of the status. This includes preparing, on a once every two-year cycle of the Arctic Council chairmanship, a high level “Summary of Progress and Recommendations” report, with appropriate conclusions and recommendations. To support the process Arctic States agreed to submit biennial national reports on their existing and planned actions to reduce black carbon and methane, national inventories of these pollutants and projections of future emissions, where available. All Arctic States, seven Observer States and the European Union submitted national reports. Several countries’ reports contain their first-ever national black carbon inventory. This report presents the Finnish national report to the Arctic Counci

Pitkän aikavälin ilmasto- ja energiastrategian ympäristöarviointi

Arvioinnissa tarkasteltiin erityisesti niitä pitkän aikavälin ilmasto- ja energiastrategian ympäristövaikutuksia, jotka voivat syntyä kasvihuonekaasupäästöjen vähentämisen lisäksi. Pääasiassa ilmastonmuutosta hillitsevät toimet, kuten energiansäästö ja uusiutuvan energiantuotannon lisäys, vähentävät myös ilmansaasteiden päästöjä, mutta esimerkiksi puun pienpoltto aiheuttaa pienhiukkaspäästöjä. Kun päästöt tapahtuvat matalalla ja lähellä suuria ihmiskeskittymiä, väestö altistuu suuremmille epäpuhtauksien pitoisuuksille kuin silloin, kun päästöt tulevat korkeista piipuista. Erityisesti on syytä rajoittaa liikenteen ei-pakokaasuperäisiä päästöjä (”katupöly”) kaupungeissa ja puun pienpolton päästöjä tiheästi asutuilla alueilla. Elinkaariarviointiin perustuva skenaarioiden ympäristövaikutusarviointi osoittaa, että polttoaineiden valmistuksen ja käytön yhteenlasketut vaikutukset pienenevät kaikissa tarkastelluissa vaikutusluokissa vuoteen 2005 verrattuna. Tämä johtuu pääasiassa kotimaan käytön vaikutusten vähenemisestä. Polttoaineiden valmistuksen vaikutukset ulkomailla lisääntyvät, mikä johtuu fossiilisten energialähteiden tuonnin kasvusta. Ympäristöanalyysin perusteella typen oksidien ja pienhiukkasten päästöjen rajoittaminen on keskeisin päästövähennystoimenpidealue hiilidioksidipäästöjen rajoittamisen jälkeen. Monet strategian linjaukset ja toimenpiteet pyrkivät viemään kehitystä kohti energiaa säästävää ja vähemmän luonnonvaroja kuluttavaa tuotantoa ja kulutusta, mutta kokonaiskulutuksena mitattuna muutos vuosien 2005 ja 2020 välillä on skenaarioissa verrattain pieni. Merkittävämpi muutos voi toteutua pitkällä aikavälillä, jos ilmasto- ja energiapolitiikka johdonmukaisesti kannustaa säästämään energiaa ja luonnonvaroja niin, että myös absoluuttinen kulutus pienenee. Aikaisempien ilmasto- ja energiastrategioiden toimenpiteiden seuranta osoittaa, että lukuisia erilaisia energiatehokkuutta edistäviä hankkeita on käynnistetty, mutta merkittäviä rakenteellisia muutoksia energiankulutuksessa ei ole vielä tapahtunut. Osana ilmastopolitiikkaa Suomi on kerännyt kokemuksia ns. Kioton mekanismien soveltamisesta. Tarkastelu osoittaa, että näiden mekanismien avulla voidaan edistää myös yleisiä kehityspoliittisia tavoitteita, mutta tämä edellyttää toiminnan aktiivista suuntaamista myös monenkeskisellä tasolla

Near-term climate impacts of Finnish residential wood combustion

Residential wood combustion (RWC) is a major source of climate-impacting emissions, like short-lived climate forcers (SLCF) and biogenic CO2, in Finland. In this paper, we present projections for those emissions from 2015 to 2040. We calculated the climate impact of the emissions using regional temperature potential metrics presented in literature. In our results, the climate impacts are given as global and Arctic temperature responses caused by the studied emissions in a 25 year time span. The results show that SLCF emissions from RWC cause a significant warming impact. Using our selected metrics, SLCF emissions from RWC added to the warming impact of Finland's projected greenhouse gas emissions by 28% in global temperature response and by 170% in Arctic response. When compared with other common heating methods in Finnish detached houses, using a typical Finnish stove (masonry heater) was the least climate-friendly option. Taking biogenic CO2 emissions into account further highlighted this finding. Finally, we assessed the change in climate impact when implementing various emission reduction measures for RWC. With a time span of 25 years, early action was found to be even more crucial than the eventual reductions in annual emissions in 2040. Highlights • RWC is the major source of BC and many other SLCFs in Finland. • SLCF emissions from Finnish RWC have a relatively significant climate impact, compared with GHGs. • Using a stove was found to be the least climate-friendly option to heat a house. • Biogenic CO2 emissions need to be included in assessments. • Early action is key in SLCF emission reduction measures