Secondary Organic Aerosol Generation Research Articles

Characteristics and Source Apportionment of VOCs Initial Mixing Ratio in Beijing During Summer

To clarify the characteristics and source apportionment of the VOCs initial mixing ratio in Beijing in summer, continuous monitoring of VOCs was conducted in the Beijing urban area from May to August 2022, and the initial mixing ratio was calculated using the photochemical ratio method. The results showed that:① during the study period, initial φ(TVOCs) in the Beijing urban area were (30.0 ±11.5)×10-9, in which the proportion of VOCs and alkanes containing oxygen reached 34.2% and 33.2%, respectively. The species with high volume fractions were low carbon substances such as acetone, ethane, acetaldehyde, and propane. ② The initial TVOCs mixing ratio in Beijing showed a slightly unimodal trend, reaching the peak at 11:00 and slightly decreasing in the afternoon. ③ Isoprene, acetaldehyde, n-butanal, and ethylene were the major contributors to the generation of O3, whereas toluene, isoprene, m-paraxylene, and ethylbenzene were the major contributors to the generation of secondary organic aerosols. ④ Based on the initial mixing ratio of PMF analysis, it was found that aging background and secondary sources (30%) contributed the most to VOCs in Beijing, and motor vehicle sources (25%) were the main primary human sources. In addition, solvent and fuel volatile sources contributed 16%, combustion sources contributed 11%, industrial process sources contributed 9%, and natural sources contributed 9%. ⑤ The anthropogenic sources of Beijing were mainly from the eastern and southern regions, whereas the natural sources were from the western and northwestern regions. This research showed that vehicle emissions should be further reduced, and regional joint prevention and control to reduce VOCs in the whole region is an effective means to control VOCs in Beijing.

Methodological advances to improve repeatability of SOA generation in environmental chambers

Most laboratory atmospheric chamber studies probing the chemical and physical properties of secondary organic aerosol (SOA) perform such experiments with mixing ratios of volatile organic compounds (VOCs) above atmospheric relevance (≳50 ppbv). When performing ozonolysis of biogenic VOCs at mixing ratios of atmospheric relevance (≲10 ppbv), a major hinderance on the repeatability of replicate experiments is due to the limitations of conventional VOC injection techniques. To overcome these limitations, two novel components (stop/flow and split valves) were embedded in a conventional VOC injection setup, thereby permitting the use of higher VOC volumes of injection to attain low VOC mixing ratios, and the delivery of the VOC to the environmental chamber as a short, discrete pulse for subsequent reaction. Implementation of these novel VOC injection components has resulted in improvements in variability between replicate chamber experiments of up to a factor of 7 with respect to particle number, mass, and size distributions at both high and low VOC mixing ratios (50 and 10 ppbv, respectively). These improvements permit extension of quantitative measurements of SOA formation to VOC mixing ratios at or near atmospheric levels, where new particle formation (NPF) and SOA mass loading are typically within experimental variability.

Formation of secondary organic aerosols from the ozonolysis of Cis-3-hexenyl acetate: The effect of acidic seed particles and SO2

Cis-3-hexenyl acetate (cis-HXAC) is a major green leaf volatile released by plants, and its atmospheric degradation by O3 may play an important role in the formation of secondary organic aerosol (SOA). In this study, indoor smog chamber experiments were carried out to investigate the effects of particle acidity and SO2 on the formation of secondary organic aerosols (SOA) from the ozonolysis of cis-HXAC. Particle formation and growth were characterized using a scanning mobility particle sizer, and the chemical composition of the particles was analyzed by thermal-desorption gas chromatography mass spectrometry, with the main products and reaction pathways of cis-HXAC ozonolysis being identified. The results revealed that acidic seed particles inhibited SOA formation compared to non-acidic seed particles, and SO2 was considered to play a catalytic role in cis-HXAC ozonolysis, showing a good positive correlation with SOA generation. The results of this study provide new information on the ozonolysis of cis-HXAC, confirm the important role of anthropogenic pollution, and help to further elucidate the potential of green leaf volatiles ozonolysis to generate SOA under complex pollution conditions.

Review of the influencing factors of secondary organic aerosol formation and aging mechanism based on photochemical smog chamber simulation methods

The formation and aging mechanism of secondary organic aerosol (SOA) and its influencing factors have attracted increasing attention in recent years because of their effects on climate change, atmospheric quality and human health. However, there are still large errors between air quality model simulation results and field observations. The currently undetected components during the formation and aging of SOA due to the limitation of current monitoring techniques and the interactions among multiple SOA formation influencing factors might be the main reasons for the differences. In this paper, we present a detailed review of the complex dynamic physical and chemical processes and the corresponding influencing factors involved in SOA formation and aging. And all these results were mainly based the studies of photochemical smog chamber simulation. Although the properties of precursor volatile organic compounds (VOCs), oxidants (such as OH radicals), and atmospheric environmental factors (such as NOx, SO2, NH3, light intensity, temperature, humidity and seed aerosols) jointly influence the products and yield of SOA, the nucleation and vapor pressure of these products were found to be the most fundamental aspects when interpreting the dynamics of the SOA formation and aging process. The development of techniques for measuring intermediate species in SOA generation processes and the study of SOA generation and aging mechanism in complex systems should be important topics of future SOA research.

VOC emitted by biopharmaceutical industries: Source profiles, health risks, and secondary pollution

The biopharmaceutical industry contributes substantially to volatile organic compounds (VOCs) emissions, causing growing concerns and social developmental conflicts. This study conducted an on-site investigation of the process-based emission of VOCs from three biopharmaceutical enterprises. In the workshops of the three enterprises, 26 VOCs were detected, which could be sorted into 4 classes: hydrocarbons, aromatic hydrocarbons, oxygen-containing compounds, and nitrogen-containing compounds. Ketones were the main components of waste gases, accounting for 44.13%–77.85% of the overall VOCs. Process-based source profiles were compiled for each process unit, with the fermentation and extraction units of tiamulin fumarate being the main source of VOC emissions. Dimethyl heptanone, vinyl acetate, diethylamine, propylene glycol methyl ether (PGME), and benzene were screened as priority pollutants through a fuzzy comprehensive evaluation system. Ground level concentration simulation results of the Gauss plume diffusion model demonstrated that the diffusivity of VOCs in the atmosphere was relatively high, indicating potential non-carcinogenic and carcinogenic risks 1.5–2 km downwind. Furthermore, the process-based formation potentials of ozone and secondary organic aerosols (SOAs) were determined and indicated that N-methyl-2-pyrrolidone, dimethyl heptanone, and PGME should be preferentially controlled to reduce the ozone formation potential, whereas the control of benzene and chlorobenzene should be prioritized to reduce the generation of SOAs. Our results provide a basis for understanding the characteristics of VOC emission by biopharmaceutical industries and their diffusion, potentially allowing the development of measures to reduce health risks and secondary pollution.

Characteristics of Volatile Organic Compounds and Their Contribution to Secondary Organic Aerosols during the High O3 Period in a Central Industry City in China

High loads of fine particulate matter (PM2.5) and ozone (O3) pollution occurred frequently since early spring and led to an increasing contribution of secondary organic aerosols (SOA) in organic aerosols. However, the characteristics of precursor volatile organic compounds (VOCs) have rarely been studied. In this study, the continuous observation of VOCs was performed by an offline VOC monitoring system and gas chromatography-mass/flame ionization detector from 1 April 2020 to 31 July 2020; the characterization of VOCs and their contribution to SOA was explored. The results showed that during the observation period, the average mixing ratio of TVOCs was 42.6 ± 11.2 ppbv, and the major VOCs species were OVOCs, followed by alkanes, halocarbons, aromatics, alkenes and acetylene. When the west circulation pattern functioned, the value of aromatics increased, and the relation between PM2.5, O3 and VOCs increased when the high-pressure system controlled by anticyclone functioned. In combination with the results of positive matrix factorization, the main emission sources of ambient VOCs were complex, and the fuel combustion, industry-related emission, vehicle emission, biogenic emission and solvent volatilization accounted for 27.1%, 24.4%, 24.3%, 12.1% and 12.0%, respectively. Moreover, the industry-related emission contributed the greatest to the generation of SOA. This result indicated that the restrictions on aromatics during the industrial process are vital to reducing SOA formation.

Secondary organic aerosol formation from cis-3-hexen-1-ol/NOx photo-oxidation: The roles of cis-3-hexen-1-ol concentration, illumination intensity, NOx and NH3

Cis-3-Hexen-1-ol (cis-HXO) is an important green leaf volatile (GLV), and its photochemical oxidation is an important pathway to generate secondary organic aerosol (SOA). In this study, smog chamber experiments were carried out to investigate the effects of cis-HXO concentration, illumination intensity, and nitrogen oxides (NOX) and ammonia (NH3) levels on the formation of cis-HXO photo-oxidation SOA in the presence of NOX. The number concentration, mass concentration and yield of SOA under different influencing factors were determined using a scanning mobility particle sizer (SMPS) and a single photon ionization time-of-flight mass spectrometer (SPIMS). The experimental results demonstrated that stronger illumination intensity and higher cis-HXO concentration promoted particles formation. The SOA yield showed a good positive correlation with NOX concentration, especially under high NOX conditions, due to the fragmentation of alkoxy radicals during the reaction to form more polymerizable products as well as the presence of dinitrate and trinitrate, thus promoting the production of SOA. To our surprise, although the addition of NH3 promoted the formation of particles, it inhibited the growth of particles, and thus reducing the particles geometric mean diameter. The chemical components of cis-HXO photo-oxidation SOAs were also analyzed by a thermal-desorption gas chromatography mass spectrometry (TD-GC-MS). Based on the detected products, a reaction mechanism for the cis-HXO photo-oxidation was proposed. The experimental results confirm that cis-HXO is a significant global source of SOA which has a great reference significance for regional air quality prediction and more accurate modelling of global SOA generation.

Secondary organic aerosol formation from photooxidation of γ-butyro and γ-valero-lactone: A combined experimental and theoretical study

The formation of secondary organic aerosol (SOA) generated by OH-photooxidation of γ-butyrolactone (GBL) and γ-valerolactone (GVL) in the presence of OH, NO, H2O vapour and aerosol seeds ((NH4)2SO4 and CaCl2) has been investigated for the first time. Experiments were conducted in a smog chamber at 298 K and atmospheric pressure. Lactone's decay was followed by gas chromatography with a mass spectrometric detector (GC-MS), and the temporal evolution of the SOA was monitored using a fast mobility particle sizer (FMPS). The SOA yield increases slightly when the initial GVL concentration increases. On the other hand, SOA formation is minor for GBL, and it rises slightly at low concentrations. In the case of GVL, the organic aerosol formation can be tentatively expressed by a one-product gas/particle partitioning absorption model. The particle number concentration, mass and yield decrease in the presence of NO but increase at higher relative humidity (RH) and seed surface area within the studied range. Acetic acid and succinic anhydride for GVL, and succinic anhydride for GBL were experimentally identified as oxidation products both in gas and particle phase using thermal desorption followed by GC-MS. Moreover, the theoretical studies carried out to complement the experimental results indicate that H-abstraction at the carbon site adjacent to the heterocyclic oxygen is the predominant pathway, being even more favourable when H2O was added. Also, under atmospheric conditions, the opening of the ring of the corresponding oxy-radicals and their subsequent fragmentation could be the possible explanation for the formation of detected products and the higher yield of SOA in the presence of H2O and absence of NO. Considering these results, the formation of SOA from the use of both lactones as potential biofuels is few significative, although SOA generation may be enhancement by particle-phase heterogeneous reactions catalyzed by humidity and the acidity of seed aerosols present in real atmosphere.

Generation of secondary organic aerosols on needle surfaces and their entry into the winter forest canopy under radiometric photophoresis

Generation of secondary organic aerosols on needle surfaces and their entry into the winter forest canopy under radiometric photophoresis

Reduction of Volatile Organic Compounds (VOCs) Emissions from Laundry Dry-Cleaning by an Integrated Treatment Process of Condensation and Adsorption

Volatile organic compounds (VOCs) are intermittently emitted at high concentrations (tens of thousands of ppmv) from small-scale laundry shops in urban areas, affecting the urban atmospheric environment. In this study, we suggested integrating VOC treatment processes incorporating condensation and adsorption in series to remove VOCs released from small-scale laundry dryers (laundry weighing less than 30 kg). We designed two different processes depending on regeneration modes for adsorber beds; an open-circuit flow process and a closed-loop flow process in regeneration mode. Our VOC treatment processes enable sustainable operation via the regeneration of adsorbers on a regular basis. Before applying the VOC treatment processes, average concentration of total volatile organic compounds (TVOCs) was 4099 ppmv (12,000 ppmv of the peak concentration) during the drying operation. After applying our closed-loop flow process, TVOC concentration decreased to 58 ppmv, leading to 98.5% removal efficiency. We also verified the robustness of our process performance in a continuous operation (30 cycles) by using a process simulation program. Lastly, we observed that our integrated treatment process can contribute to reductions in ozone and secondary organic aerosol generation by 90.4% and 95.9%, respectively. We concluded that our integrated VOC treatment processes are applicable to small-scale laundry shops releasing high-concentration VOCs intermittently, and are beneficial to the atmospheric environment.

Emissions of Volatile Organic Compounds (VOCs) from an Open-Circuit Dry Cleaning Machine Using a Petroleum-Based Organic Solvent: Implications for Impacts on Air Quality

Volatile organic compounds (VOCs) are known to play an important role in tropospheric chemistry, contributing to ozone and secondary organic aerosol (SOA) generation. Laundry facilities, using petroleum-based organic solvents, are one of the sources of VOCs emissions. However, little is known about the significance of VOCs, emitted from laundry facilities, in the ozone and SOA generation. In this study, we characterized VOCs emission from a dry-cleaning process using petroleum-based organic solvents. We also assessed the impact of the VOCs on air quality by using photochemical ozone creation potential and secondary organic aerosol potential. Among 94 targeted compounds including toxic organic air pollutants and ozone precursors, 36 compounds were identified in the exhaust gas from a drying machine. The mass emitted from one cycle of drying operation (40 min) was the highest in decane (2.04 g/dry cleaning). Decane, nonane, and n-undecane were the three main contributors to ozone generation (more than 70% of the total generation). N-undecane, decane, and n-dodecane were the three main contributors to the SOA generation (more than 80% of the total generation). These results help to understand VOCs emission from laundry facilities and impacts on air quality.

Detection of organosulfates and nitrooxy-organosulfates in Arctic and Antarctic atmospheric aerosols, using ultra-high resolution FT-ICR mass spectrometry

Organosulfates (OSs) are recognized as important secondary organic aerosols (SOAs) in recent years. Due to their amphipathy and light absorptive capacity, OSs may potentially impact climate. Moreover, OSs can serve as molecular tracers for precursors and multiple processes leading to the generation of SOA. However, studies on OSs are lacking in the polar regions which limits our understanding of both their formation pathways and impacts on the polar environment. Here we present the first investigation into OSs in both the Arctic and Antarctic. Organic compounds in aerosol samples collected from the polar regions during the 2013/2014 Chinese National Arctic/Antarctic Research Expedition (CHINARE) were analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) coupled with negative ion mode electrospray ionization (ESI(−)). Hundreds to thousands of OSs were detected at the polar sampling sites. The estimated total concentrations of OSs were in the range of 46–670 ng/m3 in the Arctic sampling area, and 47–260 ng/m3 in the Antarctic sampling area, accounting for 1–16% of total OM. OSs were found to have undergone a high degree of oxidation in the aerosol samples, which might be due to the combined effects of enhanced photo-oxidation in summertime or continuous oxidation during transport to the polar region. The potential appointment of OS precursors highlights the important role of long-range air-mass transport on the OSs derived from biogenic precursors and a notably large contribution from anthropogenic emissions, suggesting that human activities have significant impacts in remote polar environments. The results of this study provide important insights into the characteristics of OSs in the polar atmosphere. However, the need for further research focusing on the quantification, formation mechanisms and impacts of OSs on climate is emphasized.

Temporal Variation and Source Analysis of Carbonaceous Aerosol in Industrial Cities of Northeast China during the Spring Festival: The Case of Changchun

Carbonaceous aerosol, one of the major components of atmospheric aerosols, significantly affects haze episodes, climate change, and human health. Northeastern China suffers severe air pollution, especially in some periods (e.g., the Spring Festival). However, studies on carbonaceous aerosols in typical northeast industrial cities (i.e., Changchun) are rare, limiting further comprehension of the atmospheric haze formation. In this study, we monitored the concentrations of carbonaceous aerosols (i.e., OC and EC) in Changchun during the Lunar New Year of 2018 (i.e., from Lunar 20 December to Lunar 20 January), and analyzed the temporal variation and source contributions via the HYbrid-Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model with the potential source contribution factor weights (PSCF) method. The daily concentrations of OC and EC were 9.00 ± 2.81 and 1.57 ± 0.46 µg m−3, respectively, and were significantly lower at nighttime than at the day during the Spring Festival. The concentrations during the major period (i.e., OC: 8.13 ± 2.93 µg m−3; EC: 1.47 ± 0.47 µg m−3 in festival days), including the Lunar Little New Year; the Lunar New Year’s Eve; New Year’s Day; Lunar 5 January, and the Spring Lantern Festival, were mainly from the northwestward with the wind speed of 4–6 m/s being lower than that of normal period (OC: 9.87 ± 2.46 µg m−3; EC: 1.67 ± 0.44 µg m−3) from the southeastward with a wind speed of 6–7 m/s. The direction of the airflow trajectory was mainly in local, northwestward, and northward, carrying particulate matter and gaseous pollutants. In major period, the daily concentration of atmospheric pollutants presented a bimodal trend, with peaks appearing regularly from 11:00 a.m. to 12:00 p.m. and 5:00 p.m. 10:00 p.m., which might be related to traffic, cooking, and firecrackers. The OC/EC was greater than 2 during the whole period, indicating the generation of secondary organic aerosols (i.e., SOC). This study was essential to understand the formation mechanisms of severe pollution episodes and develop control measures for the industrial cities of Northeast China during the Spring Festival.

Atmospheric fate of two relevant unsaturated ketoethers: kinetics, products and mechanisms for the reaction of hydroxyl radicals with (<i>E</i>)-4-methoxy-3-buten-2-one and (1<i>E</i>)-1-methoxy-2-methyl-1-penten-3-one

Abstract. The kinetics of the gas phase reactions of hydroxyl radicals with two unsaturated ketoethers (UKEs) at (298±3) K and 1 atm of synthetic air have been studied for the first time using the relative-rate technique in an environmental reaction chamber by in situ Fourier-transform infrared spectroscopy (FTIR). The rate coefficients obtained using propene and isobutene as reference compounds were (in units of 10−10 cm3 molecule−1 s−1) as follows: kTMBO (OH + (E)-4-methoxy-3-buten-2-one) = (1.41±0.11) and kMMPO (OH + (1E)-1-methoxy-2-methyl-1-penten-3-one) = (3.34±0.43). In addition, quantification of the main oxidation products in the presence of NOx has been performed, and degradation mechanisms for these reactions were developed. Methyl formate, methyl glyoxal, peroxyacetyl nitrate (PAN) and peroxypropionyl nitrate (PPN) were identified as main reaction products and quantified for both reactions. The results of the present study provide new insights regarding the contribution of these multifunctional volatile organic compounds (VOCs) in the generation of secondary organic aerosols (SOAs) and long-lived nitrogen containing compounds in the atmosphere. Atmospheric lifetimes and implications are discussed in light of the obtained results.

Emission behavior, environmental impact and priority-controlled pollutants assessment of volatile organic compounds (VOCs) during asphalt pavement construction based on laboratory experiment

Volatile organic compounds (VOCs) release from asphalt pavement construction is a potential emission source. The detailed emission behaviors were simulated in the laboratory, and the corresponding environmental impact was investigated as well. A set of dedicated devices were applied to mirror 3 representative scenarios namely mixture plant, transportation and paving processes with VOCs emission concentrations varied from 4.24 mg/m3 to 104.16 mg/m3. Ozone formation potential (OFP) and secondary organic aerosol (SOA) were built to evaluate the environmental impact, indicating that the reactive ability differed in the specified substances. The alkenes (n ≤ 4) and aldehydes, alkanes (n ≥ 6) and alkylbenzenes with relative lower concentration were the main sources for the OFP and SOA generation, and they contributed to more than 62% OFP and 97% SOA respectively. The top 10 contributors to concentration, OFP and SOA had been identified. For the complex species existed in VOCs emission and the lack of VOCs control standards, this study provided possible access to screen priority-controlled pollutants based on information entropy method, in terms of both environmental and human health impact. In addition, the first-class priority-controlled species had been determined, urgently needing more attention in the future VOCs management during asphalt pavement construction.

Secondary organic aerosol formation from styrene photolysis and photooxidation with hydroxyl radicals

The formation of secondary organic aerosol (SOA) generated by irradiating styrene in the presence and/or absence of OH, NOx, H2O vapour and seed aerosol has been investigated for the first time. Experiments were conducted in a smog chamber at 298 K and atmospheric pressure. Styrene decay was measured by gas chromatography with a mass spectrometric detector (GC-MS), and the temporal evolution of the aerosol was monitored using a fast mobility particle sizer (FMPS). The SOA yield increases as the initial styrene concentration increases, leading to yields ranging from 1.8% to 3.5% for styrene photolysis, and from 2.4% to 5.0% for its photooxidation. In both cases, the organic aerosol formation can be expressed by a one-product gas/particle partitioning absorption model. The particle number concentration, mass and yield decrease in the presence of NOx and seed aerosol but increase at higher relative humidity (RH). The gas phase and SOA composition were analysed offline using a filter/denuder sampling system simultaneously collecting gas- and particle-phase products. Benzaldehyde was confirmed as the main gas-phase product of the reaction. However, although products in the particle phase were detected, they could not be identified. Moreover, the aqueous filter extracts were analysed using UV–Visible spectrophotometry to determine differences in the optical properties of SOA produced in the presence and absence of NOx. The results from this work may be used to discuss the implications of atmospheric SOA generation from styrene degradation.

Impact of Temperature on Secondary Organic Aerosol Generation

Impact of Temperature on Secondary Organic Aerosol Generation

Experimental and model estimates of the contributions from biogenic monoterpenes and sesquiterpenes to secondary organic aerosol in the southeastern United States.

Atmospheric organic aerosol (OA) has important impacts on climate and human health but its sources remain poorly understood. Biogenic monoterpenes and sesquiterpenes are important precursors of secondary organic aerosol (SOA), but the amounts and pathways of SOA generation from these precursors are not well constrained by observations. We propose that the less-oxidized oxygenated organic aerosol (LO-OOA) factor resolved from positive matrix factorization (PMF) analysis on aerosol mass spectrometry (AMS) data can be used as a surrogate for fresh SOA from monoterpenes and sesquiterpenes in the southeastern US. This hypothesis is supported by multiple lines of evidence, including lab-in-the-field perturbation experiments, extensive ambient ground-level measurements, and state-of-the-art modeling. We performed lab-in-the-field experiments in which the ambient air is perturbed by the injection of selected monoterpenes and sesquiterpenes, and the subsequent SOA formation is investigated. PMF analysis on the perturbation experiments provides an objective link between LO-OOA and fresh SOA from monoterpenes and sesquiterpenes as well as insights into the sources of other OA factors. Further, we use an upgraded atmospheric model and show that modeled SOA concentrations from monoterpenes and sesquiterpenes could reproduce both the magnitude and diurnal variation of LO-OOA at multiple sites in the southeastern US, building confidence in our hypothesis. We estimate the annual average concentration of SOA from monoterpenes and sesquiterpenes in the southeastern US to be roughly 2 μg m-3.

Terpene Composition Complexity Controls Secondary Organic Aerosol Yields from Scots Pine Volatile Emissions

Secondary organic aerosol (SOA) impact climate by scattering and absorbing radiation and contributing to cloud formation. SOA models are based on studies of simplified chemical systems that do not account for the chemical complexity in the atmosphere. This study investigated SOA formation from a mixture of real Scots pine (Pinus sylvestris) emissions including a variety of monoterpenes and sesquiterpenes. SOA generation was characterized from different combinations of volatile compounds as the plant emissions were altered with an herbivore stress treatment. During active herbivore feeding, monoterpene and sesquiterpene emissions increased, but SOA mass yields decreased after accounting for absorption effects. SOA mass yields were controlled by sesquiterpene emissions in healthy plants. In contrast, SOA mass yields from stressed plant emissions were controlled by the specific blend of monoterpene emissions. Conservative estimates using a box model approach showed a 1.5- to 2.3-fold aerosol enhancement when the terpene complexity was taken into account. This enhancement was relative to the commonly used model monoterpene, “α-pinene”. These results suggest that simplifying terpene complexity in SOA models could lead to underpredictions in aerosol mass loading.

Estimation of the contribution of secondary organic aerosol to PM2.0 concentration in aircraft cabins

Ozone (O3) and many kinds of reactive organic compounds (ROGs) are commonly found in aircraft cabins. Thus the secondary organic aerosol (SOA) which form as the products of oxidative reactions with ROGs may be an important potential source of fine particles in aircraft cabins. This study aims to estimate the contribution of SOA to the concentration of PM2.0 (particles with aerodynamic diameter less than 2.0 μm) in aircraft cabins. Based on the measurements of O3 and ROGs concentration in the aircraft cabins of five flights in China, a SOA formation model was employed to estimate the concentration of SOA generated from the oxidation of ROGs. O3 concentration, the fraction of organic aerosol (OA) mass (sum of organic aerosol components from outdoor sources (OOA), organic aerosol components emitted by primary indoor sources (POA) and SOA), the concentration of the PM2.0 and the deposition rate of particle matter (PM) that affecting SOA generation were investigated. The results show that the SOA contribution could reach to 56% in some cases, the average SOA contribution ranges from zero to 20% for the five studied flights. The O3 concentration, POA mass fraction and the concentration of PM2.0 are all important factors influencing the SOA contribution. The deposition rate of PM has little effect on the SOA generation.