Modeling secondary organic aerosol formation from volatile chemical products

Abstract

Abstract. Volatile chemical products (VCPs) are commonly-used consumer and industrial items that are an important source of anthropogenic emissions. Organic compounds from VCPs evaporate on atmospherically relevant time scales and include many species that are secondary organic aerosol (SOA) precursors. However, the chemistry leading to SOA, particularly that of intermediate volatility organic compounds (IVOCs), has not been fully represented in regional-scale models such as the Community Multiscale Air Quality (CMAQ) model, which tend to underpredict SOA concentrations in urban areas. Here we develop a model to represent SOA formation from VCP emissions. The model incorporates a new VCP emissions inventory and employs three new classes of emissions: siloxanes, oxygenated IVOCs, and nonoxygenated IVOCs. VCPs are estimated to produce 1.67 μg m−3 of noontime SOA, doubling the current model predictions and reducing the SOA mass concentration bias from −75 % to −58 % when compared to observations in Los Angeles in 2010. While oxygenated and nonoxygenated intermediate volatility VCP species are emitted in similar quantities, SOA formation is dominated by the nonoxygenated IVOCs. Formaldehyde and SOA show similar relationships to temperature and bias signatures indicating common sources and/or chemistry. This work suggests that VCPs contribute up to half of anthropogenic SOA in Los Angeles and models must better represent SOA precursors from VCPs to predict the urban enhancement of SOA.

Volatile Chemical Product Enhancements to Criteria Pollutants in the United States

“…In current and previous public, operational versions of CMAQ, lower-volatility, gas-phase anthropogenic ROC emissions were not represented in the chemical mechanism . As a result, much of the VCP mass (∼30%), often dominated by IVOCs, was not considered for SOA or radical chemistry. Recent work , introduced several new chemical components to the AERO7 module within CMAQ to alleviate this issue with a focus on alkane-like IVOCs, oxygenated IVOCs, SVOCs, and siloxanes, and modeled Los Angeles air quality during the 2010 California Nexus of Air Quality and Climate Change (CalNex) campaign …”

“…Here, we incorporate a new VCP inventory 9 into the Community Multiscale Air Quality (CMAQ) model with VCP-specific chemistry updates 21 to better represent VCP emissions and subsequent air quality impacts throughout the contiguous United States. These updates include the representation of secondary air pollutant formation pathways for alkane-like IVOCs, oxygenated IVOCs, and siloxanes.…”

Impacts of condensable particulate matter on atmospheric organic aerosols and fine particulate matter (PM2.5) in China

“…Wu et al (2019) constructed an inventory of S/IVOCs for the Pearl River Delta (PRD) region in China and conducted a simulation using the Weather Research and Forecasting model with Chemistry (WRF-Chem) that led to an increase of 161 % in SOA predictions. Emissions of S/IVOCs from mobile sources and IVOCs from volatile chemical products were also parameterized in models to represent SOA formation (Jathar et al, 2017;Lu et al, 2020;Pennington et al, 2021). Although the significant role of potential emission sources in OA formation has been demonstrated, the underestimation of SOA by current air quality models has not been completely resolved.…”

Yields and molecular composition of gas phase and secondary organic aerosol from the photooxidation of the volatile consumer product benzyl alcohol: formation of highly oxygenated and hydroxy nitroaromatic compounds

“…Their emissions can be larger than those from usual sources, such as motor vehicles (Coggon et al, 2021). Laboratory, modeling, and field studies for VCPs have been conducted to assess their potential to affect ambient OA and ozone formation in urban and suburban locations (McDonald et al, 2018;Khare et al, 2018;Stockwell et al, 2021;Seltzer et al, 2021;Gkatzelis et al, 2021;Milani et al, 2021;Pennington et al, 2021;Coggon et al, 2021). The contribution of VCPs to ambient OA is not fully understood and only limited modeling studies have been reported (Mohr et al, 2015;Vlachou et al, 2018;Pennington et al, 2021;Qin et al, 2021;Seltzer et al, 2021).…”

“…Laboratory, modeling, and field studies for VCPs have been conducted to assess their potential to affect ambient OA and ozone formation in urban and suburban locations (McDonald et al, 2018;Khare et al, 2018;Stockwell et al, 2021;Seltzer et al, 2021;Gkatzelis et al, 2021;Milani et al, 2021;Pennington et al, 2021;Coggon et al, 2021). The contribution of VCPs to ambient OA is not fully understood and only limited modeling studies have been reported (Mohr et al, 2015;Vlachou et al, 2018;Pennington et al, 2021;Qin et al, 2021;Seltzer et al, 2021). Additionally, few experimental and chamber studies of VCPs have been conducted with limited characterization of aerosol products Johnston, 2016, 2017;Harrison and Well, 2012;Charan et al, 2020Charan et al, , 2021Humes et al, 2022).…”