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Atmospheric Environment (v.45, #22)
Evaluation of a road dust suspension model for predicting the concentrations of PM10 in a street canyon by M. Kauhaniemi; J. Kukkonen; J. Härkönen; J. Nikmo; L. Kangas; G. Omstedt; M. Ketzel; A. Kousa; M. Haakana; A. Karppinen (pp. 3646-3654).
We have slightly refined, evaluated and tested a mathematical model for predicting the vehicular suspension emissions of PM10. The model describes particulate matter generated by the wear of road pavement, traction sand, and the processes that control the suspension of road dust particles into the air. However, the model does not address the emissions from the wear of vehicle components. The performance of this suspension emission model has been evaluated in combination with the street canyon dispersion model OSPM. We used data from a measurement campaign that was conducted in the street canyon Runeberg Street in Helsinki from 8 January to 2 May, 2004. The model reproduced fairly well the seasonal variation of the PM10 concentrations, also during the time periods, when studded tyres and anti-skid treatments were commonly in use. For instance, the index of agreement (IA) was 0.83 for the time series of the hourly predicted and observed concentrations of PM10. The predictions of the model were found to be sensitive to precipitation and street traction sanding. The main uncertainties in the predictions are probably caused by (i) the cleaning processes of the streets, which are currently not included in the model, (ii) the uncertainties in the estimation of the sanding days, and (iii) the uncertainties in the evaluation of precipitation. This study provides more confidence that this model could potentially be a valuable tool of assessment to evaluate and forecast the suspension PM10 emissions worldwide. However, a further evaluation of the model is needed against other datasets in various vehicle fleet, speed and climatic conditions.► We present a refined mathematical model for vehicular PM10 suspension emissions. ► The model reproduced fairly well the seasonal variation of the PM10. ► The predictions were found to be sensitive to precipitation and traction sanding. ► Uncertainties also caused by the street cleaning, not accounted in the model. ► Can be a valuable tool to evaluate and forecast the suspension emissions worldwide.
Keywords: Road dust; Suspension; Model; PM; 10; Helsinki
Constitutive versus heat and biotic stress induced BVOC emissions in Pseudotsuga menziesii by É. Joó; J. Dewulf; C. Amelynck; N. Schoon; O. Pokorska; M. Šimpraga; K. Steppe; Marc Aubinet; H. Van Langenhove (pp. 3655-3662).
Induced volatiles have been a focus of recent research, as not much is known of their emission behavior or atmospheric contribution. BVOC emissions were measured from Pseudotsuga menziesii saplings under natural environmental conditions, using a dynamic branch enclosure system and GC–MS for their analysis. We determined temperature and light dependency of the individual compounds, studied seasonality of the emissions and discuss the effect of heat stress in comparison with two specific biotic stresses that occurred naturally on the trees.A standardized emission rate of 6.8 μg g(dw)−1 h−1 for monoterpenes under stressed conditions was almost a magnitude higher than that obtained for healthy trees (0.8 ± 0.2 μg g(dw)−1 h−1), with higher beta factors characterizing the stressed trees. The response of the emissions to light intensity was different for the individual compounds, suggesting a distinct minimum light intensity to reach saturation. Heat stress changed the relative contribution of specific volatiles, with larger extent of increase of sesquiterpenes, methyl salicylate and linalool emissions compared to monoterpenes. Biotic stress kept low the emissions of sesquiterpenes, (E)-4,8-dimethyl-1,3,7-nonatriene and methylbutenol isomers, and increased the level of methyl salicylate and monoterpenes. The ratio of β-pinene/α-pinene was also found to be significantly enhanced from 1.3 to 2.4 and 3.2 for non-stressed, heat stressed and combined biotic and heat stressed, respectively.Emissions of biogenic volatile organic compounds were characterized from (a) healthy, (b) aphid infested and (c) a severely diseased (with symptoms similar to Phytophthora spp.) Pseudotsuga menziesii trees.Display Omitted► MT emission under stress was a magnitude higher than obtained for healthy trees. ► Ratio of β-pinene/α-pinene was enhanced under stress, among other compound ratios. ► Saturated emission rates were observed at different light intensities for compounds.
Keywords: Sesquiterpene; Methyl salicylate; Stress; Induced VOC; Pseudotsuga menziesii; Fagus sylvatica; L
A study on the potential applications of satellite data in air quality monitoring and forecasting by Can Li; N. Christina Hsu; Si-Chee Tsay (pp. 3663-3675).
In this study we explore the potential applications of MODIS (Moderate Resolution Imaging Spectroradiometer) -like satellite sensors in air quality research for some Asian regions. The MODIS aerosol optical thickness (AOT), NCEP global reanalysis meteorological data, and daily surface PM10 concentrations over China and Thailand from 2001 to 2009 were analyzed using simple and multiple regression models. The AOT–PM10 correlation demonstrates substantial seasonal and regional difference, likely reflecting variations in aerosol composition and atmospheric conditions. Meteorological factors, particularly relative humidity, were found to influence the AOT–PM10 relationship. Their inclusion in regression models leads to more accurate assessment of PM10 from spaceborne observations. We further introduced a simple method for employing the satellite data to empirically forecast surface particulate pollution. In general, AOT from the previous day (day 0) is used as a predicator variable, along with the forecasted meteorology for the following day (day 1), to predict the PM10 level for day 1. The contribution of regional transport is represented by backward trajectories combined with AOT. This method was evaluated through PM10 hindcasts for 2008–2009, using observations from 2005 to 2007 as a training data set to obtain model coefficients. For five big Chinese cities, over 50% of the hindcasts have percentage error ≤ 30%. Similar performance was achieved for cities in northern Thailand. The MODIS AOT data are responsible for at least part of the demonstrated forecasting skill. This method can be easily adapted for other regions, but is probably most useful for those having sparse ground monitoring networks or no access to sophisticated deterministic models. We also highlight several existing issues, including some inherent to a regression-based approach as exemplified by a case study for Beijing. Further studies will be necessary before satellite data can see more extensive applications in the operational air quality monitoring and forecasting.► Study on numerous Asian cities. ► Satellite data for estimating surface PM. ► A method for satellite data in PM forecasting.
Keywords: Air pollution; Particulate matter; Satellite; Forecasting; China; Thailand
The AIRMEX study - VOC measurements in public buildings and schools/kindergartens in eleven European cities: Statistical analysis of the data by Otmar Geiss; Georgios Giannopoulos; Salvatore Tirendi; Josefa Barrero-Moreno; Bo R. Larsen; Dimitrios Kotzias (pp. 3676-3684).
Indoor and outdoor air concentrations as well as personal exposure concentrations of volatile organic compounds (VOCs) have been measured during 2003–2008 in public buildings, schools, kindergartens and private homes in eleven cities over Europe covering geographic areas in north, central and south Europe during different seasons within the frame of the AIRMEX (European Indoor Air Monitoring and Exposure assessment) study. A database is presented containing the results for 23 VOCs based upon approximately 1000 samples taken from 182 different working environments (offices, classrooms, waiting halls) in public buildings, schools and kindergartens, from 103 private homeplaces and from adult volunteers (148 samples). The statistical analysis of the data demonstrated that sources in the indoor environment are prevailing for most of the investigated VOCs with indoor/outdoor (I/O) concentration ratios following the order: hexanal ≈d-limonene ≫ formaldehyde > acetone > 1-butoxy-2-propanol > acetaldehyde > propanal > 1-butanol > n-undecane > methylcyclohexane > n-dodecane. For aromatic hydrocarbons the main impact was shown to be penetration from outdoor air as indicated by I/O ratios near one and is characterised by significantly higher indoor as well as outdoor concentrations in the south of Europe with respect to the north. For the terpenes, the lowest indoor concentrations were measured during the warm season, which may be explained by higher ventilation rates and reactions with ozone penetrated from outdoor air.► Prioritized pollutants measurement campaigns in 11 European cities. ► Measurement campaigns at different periods. ► Statistical analysis to investigate dependency on position and season. ► Exhaustive database of concentrations of indoor pollutants in 11 European cities.
Keywords: VOCs; Database; Indoor air quality; Geographical variation; Seasonal variation
Mercury emission and behavior in primary ferrous metal production by Naomichi Fukuda; Masaki Takaoka; Shingo Doumoto; Kazuyuki Oshita; Shinsuke Morisawa; Tadao Mizuno (pp. 3685-3691).
Ferrous metal production is thought to be a major mercury emission source because it uses large amounts of coal and iron ore, which contain trace amounts of mercury impurities. However, there is limited information about mercury emissions during the production process. In this study, we focused on the coke-oven process, sintering furnace process, and blast furnace process. We measured the mercury concentration in the raw materials, products, and byproducts to estimate the amount of mercury emitted and to investigate the behavior of mercury during the processes. Average mercury concentrations were 30.8 μg kg−1 in 54 samples of iron ore and 59.9 μg kg−1 in 33 samples of coal. The total mercury used for ferrous metal production in Japan was estimated to be 8.45 tons in 2005, with 4.07 tons from iron ore, 3.76 tons from coal, and 0.478 tons from limestone. Emissions from the sintering process accounted for more than 90% of the total emissions, and mercury in the exhaust gas was reduced using an activated coke tower and desulfurization equipment installed downstream of an electrostatic precipitator. When byproduct gas generated from coke-oven and blast furnace processes were included, mercury emissions estimates based on actual measurements were 4.08 tons y−1 (in 2005). Thus, about 50% of the mercury input in ferrous metal production was emitted to the atmosphere. The emission factor was calculated as 0.0488 g Hg ton−1 for crude steel production. The introduction of activated coke tower or desulfurization equipment in sintering furnace facilities would reduce mercury emissions.► There is limited information on mercury emissions from ferrous metal production. ► We focused on the coke-oven, sintering furnace, and blast furnace processes. ► Emissions from the sintering process accounted for over 90% of the total emissions. ► About 50% of the mercury input was emitted to the atmosphere. ► The introduction of activated coke might be a countermeasure for mercury emission.
Keywords: Mercury; Iron and steel industry; Emission; Mass balance; Sintering furnace process
A generalised model for traffic induced road dust emissions. Model description and evaluation by Janne Berger; Bruce Denby (pp. 3692-3703).
This paper concerns the development and evaluation of a new and generalised road dust emission model. Most of today’s road dust emission models are based on local measurements and/or contain empirical emission factors that are specific for a given road environment. In this study, a more generalised road dust emission model is presented and evaluated. We have based the emissions on road, tyre and brake wear rates and used the mass balance concept to describe the build-up of road dust on the road surface and road shoulder. The model separates the emissions into a direct part and a resuspension part, and treats the road surface and road shoulder as two different sources. We tested the model under idealized conditions as well as on two datasets in and just outside of Oslo in Norway during the studded tyre season. We found that the model reproduced the observed increase in road dust emissions directly after drying of the road surface. The time scale for the build-up of road dust on the road surface is less than an hour for medium to heavy traffic density. The model performs well for temperatures above 0 °C and less well during colder periods. Since the model does not yet include salting as an additional mass source, underestimations are evident under dry periods with temperatures around 0 °C, under which salting occurs. The model overestimates the measured PM10 (particulate matter less than 10 μm in diameter) concentrations under heavy precipitation events since the model does not take the amount of precipitation into account. There is a strong sensitivity of the modelled emissions to the road surface conditions and the current parameterisations of the effect of precipitation, runoff and evaporation seem inadequate.► We evaluate a generalised road dust emission model. ► The model is tested on two datasets during winter. ► The model performs well for temperatures above 0 °C. ► The current parameterisations of precipitation seem inadequate. ► The model contains a conceptual framework for further development.
Keywords: Traffic; Road dust; Road wear; Resuspension; Generalised emission model; Model framework
Atmospheric fate of hymexazol (5-methylisoxazol-3-ol): Simulation chamber studies by Teresa Vera; Amalia Muñoz; Milagros Ródenas; Mónica Vázquez; Esther Borrás; Maria Marqués; Abdelwahid Mellouki; Jack Treacy; Howard Sidebottom (pp. 3704-3710).
The gas-phase degradation of hymexazol (5-methylisoxazol-3-ol), a widely used fungicide, was investigated under atmospheric conditions at the European Photoreactor (EUPHORE) in Valencia, Spain, a large outdoor simulation chamber. The rate coefficient for the reaction of hydroxyl radicals with hymexazol was measured using a conventional relative rate technique. A value of the rate coefficient for the reaction of OH radicals with hymexazol, kOH(hymexazol) = (4.9 ± 0.4) × 10−12 cm3 molecule−1 s−1 was determined at 300 ± 5 K and atmospheric pressure. Rate coefficient data for the reaction of OH radicals with isoxazole, the unsubstituted analogue of hymexazol, was also obtained using the relative rate method, kOH (isoxazole) = (1.1 ± 0.1) × 10−12 cm3 molecule−1 s−1. The rate coefficients for photolysis of hymexazol, J(hymexazol) < 5 × 10−6 s−1, and reaction of ozone with hymexazol,kO3(hymexazol) = (3.2 ± 0.6) × 10−19 cm3 molecule−1 s−1, under atmospheric conditions were also determined. The results showed that removal of hymexazol from the atmosphere by photolysis or by reaction with ozone is slow compared to loss by reaction with OH radicals. The available kinetic data suggest that the gas-phase tropospheric degradation of hymexazol will be mainly controlled by reaction with OH and possibly NO3 radicals. The data provide the basis of an estimate for the tropospheric lifetime of approximately 1 day. The atmospheric implications of the use of hymexazol as a fungicide are discussed.► EUPHORE chambers are used to study atmospheric degradation of hymexazol. ► k(OH) and k(O3) were 4.9 × 10−12 and 3.2 × 10−19 cm3 molecule−1 s−1 respectively. ► The data provide an estimated tropospheric lifetime with respect OH around 30 h. ► Removal of hymexazol in the atmosphere and atmospheric implications are discussed.
Keywords: Fungicides; 5-Methylisoxazol-3-ol (hymexazol); Isoxazole; EUPHORE; Hydroxyl radical; Ozone; Photooxidation; Tropospheric lifetime
Characterization of organic compounds in 10- to 50-nm aerosol particles in boreal forest with laser desorption-ionization aerosol mass spectrometer and comparison with other techniques by Totti Laitinen; Mikael Ehn; Heikki Junninen; José Ruiz-Jimenez; Jevgeni Parshintsev; Kari Hartonen; Marja-Liisa Riekkola; Douglas R. Worsnop; Markku Kulmala (pp. 3711-3719).
The aim of this study was to characterize the organic composition of ambient ultrafine particles (<50nm) in a boreal forest environment and compare the analytical results obtained by different techniques with use a data analysis software. In the chromatographic techniques, particles were collected on a filter and analyzed off-line after sample preparation, whereas in the aerosol MS, particle analysis was performed directly from the particle source.Many compounds and chemical groups were identified with a laser aerosol mass spectrometer (laser AMS) and selected organic compounds, including acids, polyols, amines and aldehydes, from 50nm filter samples were quantified. Interesting components found with the laser AMS included oxygenated and aliphatic hydrocarbons, aromatic compounds, amines, and black carbon. The amines found on laser AMS may be related to new particle formation events at particle sizes 10–25nm. Correlations between the results obtained with different instruments were clarified, and the best correlations were found between laser AMS and 50-nm size filter samples. There were no correlations between the laser AMS data and meteorological data or on-line measured gas phase compounds. The black carbon found on laser AMS had moderate correlation for levoglucosan found on all-sized filter samples. Finally, the correlation analysis revealed that the information obtained from sub-50-nm size range particles and results for particles several times higher could not be directly compared.► Oxygenated, aliphatic hydrocarbons, aromatic compounds, amines, black carbon were found. ► Amines found on laser AMS related to particle formation events. ► Best correlations were found between laser AMS and 50-nm size filter samples. ► Laser AMS data and the meteorological data did not correlate. ► Black carbon correlated moderately for levoglucosan found in all-sized filter samples.
Keywords: Aerosols; Nanoparticles; Boreal forest; Organic composition; Aerosol MS
Endocrine disrupting compounds in the atmosphere of the urban area of Thessaloniki, Greece by M. Salapasidou; C. Samara; D. Voutsa (pp. 3720-3729).
The aim of this study was to investigate the occurrence of endocrine disrupting compounds (EDCs) in a complex urban atmosphere. Target compounds were alkylphenols (NP, tOP, nOP), nonylphenol monoethoxylate (NP1EO), bisphenol A (BPA), tetrabromobisphenol A (TBBPA), and phthalates (DMP, DEP, DBP, BBP, DEHP, DNOP). EDCs were determined in ambient PM10 from two sampling sites, one urban-traffic and one urban-industrial, located in the city of Thessaloniki, northern Greece.At both sites, DEHP and NP were found to be the predominant EDCs in airborne PM10. Concentrations of NP did not exhibit any spatial difference, whereas concentrations of DEHP were significantly higher at the urban-traffic site. Wind direction was not found to have any significant effect on ambient EDCs concentrations suggesting impact from local sources rather than transport; however some peak concentrations might be attributed to short-distance sources. The gas/particle partition coefficient, Kp, and the gaseous phase of EDCs were calculated by employing two approaches based on literature data (a) for the subcooled liquid vapor pressure ( PL0) and (b) the octanol-air partition coefficient ( KOA). It appeared that the g/ p partition of phthalates estimated by the KOA approach is in better agreement with experimental partition data reported by other investigators. Absorption in organic matter was found to be significant partition mechanism at the urban-traffic site.► Alkylphenols, bisphenol A and phthalates have been detected in ambient PM10. ► These compounds originated from local sources. ► The KOA approach better describes the g/ p partition of these compounds. ► Absorption in organic matter was significant partition mechanism at the traffic site.
Keywords: Alkylphenols; Atmosphere; BPA; Phthalates; PM10; TBBPA
Improved CMAQ predictions of particulate matter utilizing the satellite-derived aerosol optical depth by Daegyun Lee; Daewon W. Byun; Hyuncheol Kim; Fong Ngan; Soontae Kim; Chongbum Lee; Changrae Cho (pp. 3730-3741).
Regional air quality models such as the Community Multiscale Air Quality (CMAQ) model have been widely used to study and simulate multi-scale air quality issues. Although they are capable of providing high quality atmospheric chemistry profiles through the utilization of high resolution inputs relating meteorology and emissions with chemical reactions, they cannot simulate air quality accurately if other input data are not appropriate and reliable. There have been few studies on the importance of chemical initial conditions (ICs) as it is considered that the impact of concentration fields specified at the beginning of simulation wears off quickly. This paper demonstrates that the significant errors during the early part of the simulation can damage model predictions and conversely if the ICs are prescribed appropriately with available observations, they can compensate for the shortcomings of the air quality prediction system especially when the episode-based emissions inputs representing real-life emission variations such as forest fires as well as the effects of long-range transport events that are not reflected in the basic model inputs. The key hypothesis of the present study is that prediction of aerosols can be improved by the initialization of the aerosol fields with the satellite-derived Aerosol Optical Depth (AOD). We compare the effects of using fine mode and total AOD for the initialization in terms of regional bias characteristics. We found that the impacts of two-step initial conditions adjustments could be substantial in the case of aerosol events such as wildfires, which the present modeling system does not consider during simulation due to the deficiency in the emission inputs. The total AOD case helped to refine PM2.5 predictions over the northwestern area, where wildfire events occurred, for the fire event days improving the correlation coefficient significantly from 0.12 to 0.67. CMAQ predicted PM2.5 concentrations in the fine mode case decreased by 10–50 μg/m3 in large areas of the northwestern region, resulting in more realistic PM2.5 predictions with reduced unusual high peak cells. This study suggest that the use of initial conditions adjusted by total or fine mode AOD can help to improve PM2.5 simulations, even though further refinements of the vertical distribution of aerosols are critically needed.► Satellite derived AOD can be used to adjust initial conditions of the model.► New method developed to adjust CMAQ PM2.5 initial conditions using MODIS AOD.► Impacts of initial conditions adjustments are substantial in the aerosol event days.► Improved PM2.5 initial conditions are essential for the accurate model simulations.
Keywords: Particulate matter simulation; Aerosol simulation; Aerosol optical depth; Initial conditions; CMAQ; MODIS AOD
Mineral dust and carbonaceous aerosols in West Africa: Source assessment and characterization by Pascal Flament; Karine Deboudt; Hélène Cachier; Bernadette Châtenet; Xavier Mériaux (pp. 3742-3749).
As part of the AMMA (African Monsoon Multidisciplinary Analysis) international research project, an intensive field campaign called “Special Observing Period” (SOP 0) was carried out in West Africa during the dry season (February 2006), near M’Bour, Senegal. The aim of the ground-based sampling experiment was to determine the chemical composition of dust and carbonaceous aerosols in the surface layer, then to investigate the main source areas influencing the chemical composition of the particles. Major elements (Al, Ca and Fe), total (TC) and black carbon (BC), and water soluble ion (Na+, K+, Mg2+, NH4+, Cl−, NO3−,SO42− andPO43−) concentrations were measured. Total mass, number concentration and aethalometer measurements of PM-10 were also obtained. Mineral dust in the surface layer is principally present in the coarse fraction representing 75–90% of the collected mass (wt.%). Dust, suggested by backward trajectories of the air masses and supported by the variations of Ca/Al ratios, originates mainly from Northern Sahara. Particulate organic matter (POM) concentrations are more variable, but POM is mainly present in the fine fraction (up to 77 wt.%). Its presence is due to local sources such as domestic fire emissions rather than to remote sources as open-field vegetation fires in the Sahelian zone. Comparisons of Black Carbon (BC) concentrations measured with an aethalometer in the Ultra-violet and the Near-infrared wavelengths, show that POM originating from the adjacent Western African coast contains less aromatics than POM transported from the main biomass burning areas of the Sahelian zone. Thus, smouldering, the main combustion process for locally emitted carbon aerosols appears to generate less aromatic compounds than burning of vegetation.► In winter, dust source regions in Senegal are located in the Northern Sahara. ► Carbonaceous aerosols have their main origin in smouldering processes. ► Smouldering produce less aromatics compounds in aerosols than flaming of vegetation.
Keywords: AMMA; Senegal; Aerosols; Chemical composition; Dust; Carbonaceous
Atmospheric concentrations of DDTs and chlordanes measured from Shanghai, China to the Arctic Ocean during the Third China Arctic Research Expedition in 2008 by Xiaoguo Wu; James C.W. Lam; Chonghuan Xia; Hui Kang; Zhouqing Xie; Paul K.S. Lam (pp. 3750-3757).
In July to September 2008, air samples were collected aboard a research expedition icebreaker, Xuelong (Snow Dragon), under the support of the 2008 Chinese Arctic Research Expedition Program. DDTs and chlordanes were quantified in all samples. ∑DDTs concentrations over the whole cruise varied substantially, ranging from 2.0 to 110 pg m−3 with the average concentration of 36 ± 31 pg m−3. The fresh inputs of p,p′-DDT and o,p′-DDT indicated by DDT/DDE ratios and the relatively higher levels of p,p′-DDT and o,p′-DDT observed in East Asia and North Pacific Ocean may reflect direct transport of these compounds from the adjacent continent where continuing usage of DDT-related compounds is potentially occurring. In the Arctic, increase in sea ice melting in the summer of 2008 might result in the remobilization of DDT and enhance its atmospheric levels in this region. Air-borne pollutants arising from the fire occurring in the East Europe during the summer of 2008 might make a large contribution to higher levels of DDTs observed in the atmosphere of North Pacific Ocean and adjacent Arctic Ocean during our expedition. The ratios of o,p′-DDT/p,p′-DDT were higher than that in technical DDT but much lower than those observed in air samples from China, indicating the atmosphere during the present study was likely influenced by a mixture of DDT-containing products. The concentrations of ∑chlordanes varied between 1.8 and 11 pg m−3, with an average of 5.4 ± 2.6 pg m−3. Trans-chlordane (TC) and cis-chlordane (CC) were the most abundant among the chlordanes isomers, accounting for 40% and 39% of total chlordane for all samples. The TC/CC ratios measured in all samples were lower than in the technical mixture, reflecting the main influence by weathered chlordane. The sampling sites with low levels of TC and CC often have relatively low TC/CC ratios, and may be influenced by older air masses.► DDTs and chlordanes were investigated over the MBL from China to the Arctic Ocean. ► The levels of DDTs and chlordanes over the whole cruise varied substantially. ► Increased sea ice loss enhanced atmospheric DDT levels in the Arctic Ocean. ► Biomass burning contributed to higher levels of DDTs. ► Trans-chlordane and cis-chlordane were the most abundant of the chlordanes isomers.
Keywords: DDT; Chlordanes; Marine boundary layer; Arctic Ocean; Atmospheric concentration
A nonlinear regression model estimating single source concentrations of primary and secondarily formed PM2.5 by Kirk R. Baker; Kristen M. Foley (pp. 3758-3767).
Various approaches and tools exist to estimate local and regional PM2.5 impacts from a single emissions source, ranging from simple screening techniques to Gaussian based dispersion models and complex grid-based Eulerian photochemical transport models. These approaches either lack a realistic chemical and physical representation of the atmosphere for secondary PM2.5 formation or in the case of photochemical models may be too resource intensive for single source assessments. A simple non-linear regression model has been developed to estimate annual average downwind primary and secondarily formed PM2.5 nitrate and sulfate from single emissions sources. The statistical model is based on single emissions sources tracked with particulate source apportionment technology in a photochemical transport model. This non-linear regression model is advantageous in that the underlying data is based on single emissions sources modeled in a realistic chemical and physical environment of a photochemical model and provides downwind PM2.5 impact information with minimal resource burden. Separate regression models are developed for primary PM2.5, PM2.5 sulfate ion, and PM2.5 nitrate ion. Regression model inputs include facility emissions rates in tons per year and the distance between the source and receptor. An additional regression model input of receptor ammonia emissions is used to account for the variability in regional ammonia availability that is important for PM2.5 nitrate ion estimates.► Photochemical model source apportionment used to track single sources of PM2.5. ► A new non-linear regression model relating facility emissions to downwind PM2.5. ► Model relates SO2 to PM2.5 sulfate, source NOx & receptor NH3 to PM2.5 nitrate. ► Generalized model form for plants not included in analysis.
Keywords: Air quality modeling; Reduced form PM2.5 model; Single source PM2.5 contribution