Changes of PM2.5 concentrations and their sources in the US from 1990 to 2010

Abstract

<p>Quantification of the spatial and temporal variations in the sources of air pollutants, especially PM<sub>2.5</sub>, can inform control strategies and, potentially, the understanding of PM<sub>2.5 </sub>health effects. Three-dimensional chemical transport models (CTMs) are well suited to help address this problem, since they simulate all the major processes that impact PM<sub>2.5 </sub>concentrations and transport. In this study we quantify the changes in the concentration, exposure, composition, and sources of PM<sub>2.5 </sub>in the US from the early 1990s to the early 2010s. Significant reductions of emissions of SO<sub>2</sub>, NO<sub>x</sub>, VOCs and primary PM have taken place in the US during the last 20 years. We evaluate our understanding of the links between these emissions and concentration changes combining a chemical transport model (PMCAMx) with the Particle Source Apportionment Algorithm (PSAT) (Skyllakou et al., 2017). Results for 1990, 2001 and 2010 are presented. The reductions in SO<sub>2</sub> emissions (64% mainly from electrical generation units) during these 20 years have dominated the reductions in PM<sub>2.5</sub> leading to a 45% reduction of the sulfate levels. The predicted sulfate reductions were in excellent agreement with the available measurements. Also, the reductions in elemental carbon (EC) emissions (mainly from transportation) have led to a 30% reduction of EC concentrations. The most important source of OA through the years according to PMCAMx is biomass burning followed by biogenic SOA. OA from on-road transport has been reduced by more than a factor of 3, on the other hand changes in biomass burning OA and biogenic SOA have been modest. In 1990 90% of the US population was exposed to PM<sub>2.5 </sub>concentrations to equal and higher than the suggested annual mean by the WHO (10 μg m<sup>-3</sup>), but this reduced to 70% in 2010. Also, the predicted changes in concentrations were evaluated against the observed changes for 1990, 2001 and 2010, in order to understand if the model represents well the changes through the years.</p><p> </p><p>Skyllakou, K., Fountoukis, C., Charalampidis, P., and Pandis, S.N. (2017). Volatility-resolved source apportionment of primary and secondary organic aerosol over Europe, Atmos. Environ., 167, 1–10.</p><p> </p>

Characterizing Changes in Eastern U.S. Pollution Events in a Warming World

“…We consider the observational period during which numerous studies have documented decreasing EUS air pollution in response to emission control programs implemented in the 1990s and 2000s (Boys et al., 2014; Cooper et al., 2012; Frost et al., 2006; Murphy et al., 2011). For example, 60% decreases in sulfur dioxide emissions from 1990 to 2010 have been linked to 45% lower sulfate aerosol (Skyllakou et al., 2021). Summertime ozone decreases have been attributed to NO x and VOC emissions reductions of 40% and 14%, respectively, from 2002 to 2011 (Simon et al., 2015).…”

Effects of Secondary Organic Aerosol Water on fine PM levels and composition over US

“…The gaseous and primary particle emissions were developed by Xing et al (2013). More details about the meteorological inputs and the emissions can be found in Skyllakou et al (2021).…”

“…We use a new aerosol thermodynamics model, ISORROPIA-lite (Kakavas et al, 2022), to simulate SOAW effects on the partitioning of the inorganic components, for a year over the continental United States. The model performance has been evaluated for fine PM and its components for the examined period by Skyllakou et al (2021). The aim of our work is to quantify the SOAW contribution to the total fine PM water and to study its effects on inorganic aerosol thermodynamics and total dry fine PM levels and composition.…”