Sarah SteimerAssistant Professor
About me
My research focusses on trying to understand which airborne particles are the most detrimental to human health and how this relates to their chemical composition. It is well established that exposure to ambient particulate matter can lead to negative health effects. However, the underlying mechanisms are still not completely understood and there is a lot of uncertainty regarding which particles are the most toxic and why (differential toxicity). To study this, we are not only comparing particles from different sources, but also look at how atmospheric processing changes different particle properties including toxicity. One main tool I am using in my research are acellular assays, which have been developed as a cell-free alternative to traditional in-vitro methods. The development, testing and evaluation of such acellular assays forms another branch of my research.
If you would like to know more about my research or are interested in joining my group for a thesis project or a research internship, don’t hesitate to send me an email.
Teaching
I am currently responsible for the courses "Atmospheric Chemistry and Physics" and "Air Quality from Emission to Impacts".
I also teach a section about air quality management as part of the course "Miljöskyddsteknik" (Environmental Technology)
Research projects
Publications
A selection from Stockholm University publication database
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Gaseous emissions from brake wear can form secondary particulate matter
2024. Anil Patel (et al.). Scientific Reports 14 (1)
ArticleRoad traffic is an important source of urban air pollutants. Due to increasingly strict controls of exhaust emissions from road traffic, their contribution to the total emissions has strongly decreased over time in high-income countries. In contrast, non-exhaust emissions from road vehicles are not yet legislated and now make up the major proportion of road traffic emissions in many countries. Brake wear, which occurs due to friction between brake linings and their rotating counterpart, is one of the main non-exhaust sources contributing to particle emissions. Since the focus of brake wear emission has largely been on particulate pollutants, little is currently known about gaseous emissions such as volatile organic compounds from braking and their fate in the atmosphere. This study investigates the oxidative ageing of gaseous brake wear emissions generated with a pin-on-disc tribometer, using an oxidation flow reactor. The results demonstrate, for the first time, that the photooxidation of gaseous brake wear emissions can lead to formation of secondary particulate matter, which could amplify the environmental impact of brake wear emissions.
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Air quality impacts of a large waste fire in Stockholm, Sweden
2023. Karine Elihn (et al.). Atmospheric Environment 315
ArticleFires in waste facilities are a common occurrence. Since many waste facilities are located adjacent to densely populated areas, these fires could potentially expose large populations to the emitted pollutants. However, at the moment there are only few field studies investigating the impact of waste fire emissions on air quality since the unpredictable nature of these events makes them challenging to capture. This study investigated the impact of a large and persistent un-prescribed fire in a waste storage facility in Stockholm county, Sweden, on the local air quality of two residential areas in close proximity to the fire. In-situ measurements of particulate matter, black carbon and nitrogen oxide concentrations were conducted both during open burning and after the fire was fully covered. In addition, filter samples were collected for offline analysis of organic composition, metal content and toxicity. Strongly increased concentrations of PM10, PM2.5 and black carbon were found during the open burning period, especially when the wind was coming from the direction of the fire. In addition, elevated concentrations of particulate heavy metals and polycyclic aromatic hydrocarbons were observed in the air during the open burning period. These results show that waste fires can have a strong impact on the air quality of nearby residential areas.
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Toxicity and health effects of ultrafine particles: Towards an understanding of the relative impacts of different transport modes
2023. N. V. Srikanth Vallabani (et al.). Environmental Research 231, part 2
ArticleExposure to particulate matter (PM) has been associated with a wide range of adverse health effects, but it is still unclear how particles from various transport modes differ in terms of toxicity and associations with different human health outcomes. This literature review aims to summarize toxicological and epidemiological studies of the effect of ultrafine particles (UFPs), also called nanoparticles (NPs, <100 nm), from different transport modes with a focus on vehicle exhaust (particularly comparing diesel and biodiesel) and non-exhaust as well as particles from shipping (harbor), aviation (airport) and rail (mainly subway/underground). The review includes both particles collected in laboratory tests and the field (intense traffic environments or collected close to harbor, airport, and in subway). In addition, epidemiological studies on UFPs are reviewed with special attention to studies aimed at distinguishing the effects of different transport modes. Results from toxicological studies indicate that both fossil and biodiesel NPs show toxic effects. Several in vivo studies show that inhalation of NPs collected in traffic environments not only impacts the lung, but also triggers cardiovascular effects as well as negative impacts on the brain, although few studies compared NPs from different sources. Few studies were found on aviation (airport) NPs, but the available results suggest similar toxic effects as traffic-related particles. There is still little data related to the toxic effects linked to several sources (shipping, road and tire wear, subway NPs), but in vitro results highlighted the role of metals in the toxicity of subway and brake wear particles. Finally, the epidemiological studies emphasized the current limited knowledge of the health impacts of source-specific UFPs related to different transport modes. This review discusses the necessity of future research for a better understanding of the relative potencies of NPs from different transport modes and their use in health risk assessment.
Show all publications by Sarah Steimer at Stockholm University
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