scholarly journals Geochemical Characterization and Heavy Metal Sources in PM10 in Arequipa, Peru

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 641
Author(s):  
Jianghanyang Li ◽  
Greg Michalski ◽  
Elizabeth Joy Olson ◽  
Lisa R. Welp ◽  
Adriana E. Larrea Valdivia ◽  
...  
Keyword(s):  
Trace Elements ◽  
High Altitude ◽  
Mineral Dust ◽  
Anthropogenic Sources ◽  
World Health ◽  
Urban Site ◽  
Emission Sources ◽  
Industrial Site ◽  
Rural Sites ◽  
The City

Particulate matter smaller than 10 μm (PM10) is an important air pollutant that adversely affects human health by increasing the risk of respiratory and cardiovascular diseases. Recent studies reported multiple extreme PM10 levels at high altitude Peruvian cities, which resulted from a combination of high emissions and limited atmospheric circulation at high altitude. However, the emission sources of the PM10 still remain unclear. In this study, we collected PM10 samples from four sites (one industrial site, one urban site, and two rural sites) at the city of Arequipa, Peru, during the period of February 2018 to December 2018. To identify the origins of PM10 at each site and the spatial distribution of PM10 emission sources, we analyzed major and trace element concentrations of the PM10. Of the observed daily PM10 concentrations at Arequipa during our sampling period, 91% exceeded the World Health Organization (WHO) 24-h mean PM10 guideline value, suggesting the elevated PM10 strongly affected the air quality at Arequipa. The concentrations of major elements, Na, K, Mg, Ca, Fe, and Al, were high and showed little variation, suggesting that mineral dust was a major component of the PM10 at all the sites. Some trace elements, such as Mn and Mo, originated from the mineral dust, while other trace elements, including Pb, Sr, Cu, Ba, Ni, As and V, were from additional anthropogenic sources. The industrial activities at Rio Seco, the industrial site, contributed to significant Pb, Cu, and possibly Sr emissions. At two rural sites, Tingo Grande and Yarabamba, strong Cu emissions were observed, which were likely associated with mining activities. Ni, V, and As were attributed to fossil fuel combustion emissions, which were strongest at the Avenida Independencia urban site. Elevated Ba and Cu concentrations were also observed at the urban site, which were likely caused by heavy traffic in the city and vehicle brake wear emissions.

scholarly journals Assessment of Air Quality in School Environments in Hanoi, Vietnam: A Focus on Mass-Size Distribution and Elemental Composition of Indoor-Outdoor Ultrafine/Fine/Coarse Particles

Atmosphere ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 519
Author(s):  
Trinh Dinh Tran ◽  
Phuong Minh Nguyen ◽  
Dung Trung Nghiem ◽  
Tuyen Huu Le ◽  
Minh Binh Tu ◽  
...  
Keyword(s):  
Trace Elements ◽  
Elemental Composition ◽  
Size Distribution ◽  
World Health ◽  
Emission Sources ◽  
Mass Size Distribution ◽  
Minor Elements ◽  
Mass Size ◽  
Pm2.5 And Pm10 ◽  
Indoor And Outdoor

Indoor and outdoor ultrafine, accumulation mode, and coarse fractions collected at two preschools (S1 and S2) in Hanoi capital, Vietnam were characterized in terms of mass-size distribution and elemental composition to identify major emission sources. The sampling campaigns were performed simultaneously indoors and outdoors over four consecutive weeks at each school. Indoor average concentrations of CO2 and CO at both schools were below the limit values recommended by American Society of Heating, Refrigerating and Air-Conditioning Engineers (1000 ppm for CO2) and World Health Organization (7 mg/m3 for CO). Indoor concentrations of PM2.5 and PM10 at S1 and S2 were strongly influenced by the presence of children and their activities indoors. The indoor average concentrations of PM2.5 and PM10 were 49.4 µg/m3 and 59.7 µg/m3 at S1, while those values at S2 were 7.9 and 10.8 µg/m3, respectively. Mass-size distribution of indoor and outdoor particles presented similar patterns, in which ultrafine particles accounted for around 15–20% wt/wt while fine particles (PM2.5) made up almost 80% wt/wt of PM10. PM2.5–10 did not display regular shapes while smaller factions tended to aggregate to form clusters with fine structures. Oxygen (O) was the most abundant element in all fractions, followed by carbon (C) for indoor and outdoor particles. O accounted for 36.2% (PM0.5–1) to 42.4% wt/wt (PM0.1) of indoor particles, while those figures for C were in the range of 14.5% (for PM0.1) to 18.1% (for PM1–2.5). Apart from O and C, mass proportion of other major and minor elements (Al, Ca, Cr, Fe , K, Mg, Si, Ti) could make up to 50%, whereas trace elements (As, Bi, Cd, Co, Cr, Cu, La, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, and Zn) accounted for less than 0.5% of indoor and outdoor airborne particles. There were no significant indoor emission sources of trace and minor elements. Traffic significantly contributed to major and trace elements at S1 and S2.

scholarly journals Evaluation of chemical transport model predictions of primary organic aerosol for air masses classified by particle component-based factor analysis

2012 ◽  
Vol 12 (18) ◽  
pp. 8297-8321 ◽  
Author(s):  
C. A. Stroud ◽  
M. D. Moran ◽  
P. A. Makar ◽  
S. Gong ◽  
W. Gong ◽  
...  
Keyword(s):  
Factor Analysis ◽  
Road Traffic ◽  
Transport Model ◽  
Vertical Mixing ◽  
Organic Aerosol ◽  
Urban Site ◽  
Emission Sources ◽  
Chemical Transport Model ◽  
Model Predictions ◽  
Rural Sites

Abstract. Observations from the 2007 Border Air Quality and Meteorology Study (BAQS-Met 2007) in Southern Ontario, Canada, were used to evaluate predictions of primary organic aerosol (POA) and two other carbonaceous species, black carbon (BC) and carbon monoxide (CO), made for this summertime period by Environment Canada's AURAMS regional chemical transport model. Particle component-based factor analysis was applied to aerosol mass spectrometer measurements made at one urban site (Windsor, ON) and two rural sites (Harrow and Bear Creek, ON) to derive hydrocarbon-like organic aerosol (HOA) factors. A novel diagnostic model evaluation was performed by investigating model POA bias as a function of HOA mass concentration and indicator ratios (e.g. BC/HOA). Eight case studies were selected based on factor analysis and back trajectories to help classify model bias for certain POA source types. By considering model POA bias in relation to co-located BC and CO biases, a plausible story is developed that explains the model biases for all three species. At the rural sites, daytime mean PM1 POA mass concentrations were under-predicted compared to observed HOA concentrations. POA under-predictions were accentuated when the transport arriving at the rural sites was from the Detroit/Windsor urban complex and for short-term periods of biomass burning influence. Interestingly, the daytime CO concentrations were only slightly under-predicted at both rural sites, whereas CO was over-predicted at the urban Windsor site with a normalized mean bias of 134%, while good agreement was observed at Windsor for the comparison of daytime PM1 POA and HOA mean values, 1.1 μg m−3 and 1.2 μg m−3, respectively. Biases in model POA predictions also trended from positive to negative with increasing HOA values. Periods of POA over-prediction were most evident at the urban site on calm nights due to an overly-stable model surface layer. This model behaviour can be explained by a combination of model under-estimation of vertical mixing at the urban location, under-representation of PM emissions for on-road traffic exhaust along major urban roads and highways, and a more structured allocation of area POA sources such as food cooking and dust emissions to urban locations. A downward trend in POA bias was also observed at the urban site as a function of the BC/HOA indicator ratio, suggesting a possible association of POA under-prediction with under-representation of diesel combustion sources. An investigation of the emission inventories for the province of Ontario and the nearby US state of Indiana also suggested that the top POA area emission sources (food cooking, organic-bound to dust, waste disposal burning) dominated over mobile and point sources, again consistent with a mobile under-estimation. We conclude that more effort should be placed at reducing uncertainties in the treatment of several large POA emission sources, in particular food cooking, fugitive dust, waste disposal burning, and on-road traffic sources, and especially their spatial surrogates and temporal profiles. This includes using higher spatial resolution model grids to better resolve the urban road network and urban food cooking locations. We also recommend that additional sources of urban-scale vertical mixing in the model, such as a stronger urban heat island effect and vehicle-induced turbulence, would help model predictions at urban locations, especially at night time.

scholarly journals Distribution of toxic metals and relative toxicity of airborne PM2.5 in Puerto Rico

2021 ◽  
Author(s):  
Héctor Jirau-Colón ◽  
Jannette Toro-Heredia ◽  
Josué Layuno ◽  
Enrique Dionisio Calderon ◽  
Adriana Gioda ◽  
...  
Keyword(s):  
Puerto Rico ◽  
Toxic Metals ◽  
Airborne Particulate Matter ◽  
Bronchial Epithelium ◽  
Average Concentration ◽  
Anthropogenic Sources ◽  
Urban Site ◽  
Relative Toxicity ◽  
Potential Health ◽  
Rural Sites

AbstractThe exposure to airborne particulate matter (PM) and its constituents is an important factor to be considered when evaluating their potential health risk. Transition metals found in PM are known to contribute significantly to the exacerbation of respiratory ailments. Exposure to these constituents results in the induction of oxidative stress in the bronchial epithelium, thus promoting the secretion of inflammatory mediators. Therefore, it is important to know the contributions of PM2.5 constituents to further investigate their relationship with toxic responses and associated health risks. PM2.5 samples from three rural (Humacao, Guayama, and Guayanilla) and two urban (more populated) sites (Bayamón and Ponce) from Puerto Rico were analyzed for various inorganic constituents. A total of 59 trace elements were analyzed, of which eight were considered with the greatest toxic potential. The highest annual average concentration of PM2.5 was reported at the urban site of Ponce (5.82 ± 1.40 μg m−3), while Bayamón’s average concentration was not as high (4.69 ± 1.30 μg m−3) compared to concentrations at the rural sites Humacao, Guayama, and Guayanilla (4.33 ± 1.20 μg m−3, 4.93 ± 1.50 μg m−3, and 4.88 ± 1.20 μg m−3 respectively. The concentration at the Ponce site exhibited the highest summer value (7.57 μg m−3) compared to that of all the rural sites (~ 6.40 μg m−3). The lowest summer PM2.5 values were obtained at the Humacao site with an average of 5.76 μg m−3. Average Cu and Zn concentrations were 3- and 2-fold higher at the urban sites (0.68 ng m−3 and 6.74 ng m−3 respectively) compared to the rural sites (0.17 ng m−3 and 4.11 ng m−3). Relative toxicity of inorganic PM extract indicates Bayamón (urban) and Guayama with similar low LC50 followed by Humacao, Guayanilla, and finally Ponce (urban) with the highest LC50. Of the eight potential toxic metals considered, only Fe was found to be higher at the rural sites. To our understanding, there are different sources of emission for these metals which potentially indicate main anthropogenic sources, together with the trade winds adding periodically volcanic and African Dust Storm particulates that affect Puerto Rico. These results are the first of their kind to be reported in Puerto Rico.

scholarly journals Levels and Sources of Atmospheric Particle-Bound Mercury in Atmospheric Particulate Matter (PM10) at Several Sites of an Atlantic Coastal European Region

Atmosphere ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 33 ◽  
Author(s):  
Jorge Moreda-Piñeiro ◽  
Adrián Rodríguez-Cabo ◽  
María Fernández-Amado ◽  
María Piñeiro-Iglesias ◽  
Soledad Muniategui-Lorenzo ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Major Ions ◽  
Univariate Analysis ◽  
Anthropogenic Sources ◽  
European Region ◽  
Urban Site ◽  
Industrial Site ◽  
Atmospheric Particle ◽  
Atlantic Coastal ◽  
Suburban Site

Atmospheric particle-bound mercury (PHg) quantification, at a pg m−3 level, has been assessed in particulate matter samples (PM10) at several sites (industrial, urban and sub-urban sites) of Atlantic coastal European region during 13 months by using a direct thermo-desorption method. Analytical method validation was assessed using 1648a and ERM CZ120 reference materials. The limits of detection and quantification were 0.25 pg m−3 and 0.43 pg m−3, respectively. Repeatability of the method was generally below 12.6%. PHg concentrations varied between 1.5–30.8, 1.5–75.3 and 2.27–33.7 pg m−3 at urban, sub-urban and industrial sites, respectively. PHg concentration varied from 7.2 pg m−3 (urban site) to 16.3 pg m−3 (suburban site) during winter season, while PHg concentrations varied from 9.9 pg m−3 (urban site) to 19.3 pg m−3 (suburban site) during the summer. Other trace elements, major ions, black carbon (BC) and UV-absorbing particulate matter (UV PM) was also assessed at several sites. Average concentrations for trace metals (Al, As, Bi, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Si, Sr, V and Zn) ranged from 0.08 ng m−3 (Bi) at suburban site to 1.11 µg m−3 (Fe) at industrial site. Average concentrations for major ions (including Na+, K+, Ca2+, NH4+, Mg2+, Cl−, NO3− and SO42−) ranged from 200 ng m−3 (K+) to 5332 ng m−3 (SO42−) at urban site, 166 ng m−3 (Mg2+) to 4425 ng m−3 (SO42−) at suburban site and 592 ng m−3 (K+) to 5853 ng m−3 (Cl−) at industrial site. Results of univariate analysis and principal component analysis (PCA) suggested crustal, marine and anthropogenic sources of PHg in PM10 at several sites studied. Toxicity prediction of PHg, by using hazard quotient, suggested no non-carcinogenic risk for adults.

scholarly journals Ancient versus modern mineral dust transported to high-altitude alpine glaciers evidences saharan sources and atmospheric circulation changes

2011 ◽  
Vol 11 (1) ◽  
pp. 859-884 ◽  
Author(s):  
F. Thevenon ◽  
M. Chiaradia ◽  
T. Adatte ◽  
C. Hueglin ◽  
J. Poté
Keyword(s):  
High Altitude ◽  
Mineral Dust ◽  
Saharan Dust ◽  
Ice Age ◽  
Anthropogenic Sources ◽  
Secondary Source ◽  
Research Station ◽  
Dust Deposition ◽  
Carbonaceous Particle ◽  
Airborne Dust

Abstract. Mineral dust aerosols collected during the years 2008/09 at the high-altitude research station Jungfraujoch (46°33' N, 7°59' E; 3580 m a.s.l.) were compared to windblown mineral dust deposited at the Colle Gnifetti glacier (45°55' N, 7°52' E, 4455 m a.s.l.) over the last millennium. Insoluble dust has been characterized in terms of mineralogy, Sr and Nd isotopic ratios, and trace element composition. Results demonstrate that the Saharan origin of the airborne dust did not change significantly throughout the past. Backward trajectories analysis of modern analogs furthermore confirms that major dust sources are situated in the north-central to north-western part of the Saharan desert. By contrast, less radiogenic Sr isotopic compositions are associated with lower abundances of crustal elements during low rates of dust deposition, suggesting intercontinental transport of background dust rather than activation of a secondary source. Saharan dust mobilization and meridional advection of air masses were relatively reduced during the second part of the Little Ice Age (ca. 1690–1870), except within the greatest Saharan dust event deposited around 1780–1790. Higher dust deposition with larger mean grain size and Saharan fingerprint began ca. 20 years after the industrial revolution of 1850, suggesting that increased mineral dust transport over the Alps during the last century was primarily due to drier winters in North Africa and stronger spring/summer North Atlantic southwesterlies, rather than to direct anthropogenic sources. Meanwhile, increasing carbonaceous particle emissions from fossil fuels combustion combined to higher lead enrichment factor during the last century, point to concomitant anthropogenic sources of particulate pollutants reaching high-altitude European glaciers.

scholarly journals New particle formation at urban and high-altitude remote sites in the south-eastern Iberian Peninsula

2020 ◽  
Vol 20 (22) ◽  
pp. 14253-14271 ◽  
Author(s):  
Juan Andrés Casquero-Vera ◽  
Hassan Lyamani ◽  
Lubna Dada ◽  
Simo Hakala ◽  
Pauli Paasonen ◽  
...  
Keyword(s):  
High Altitude ◽  
Growth Rates ◽  
Mineral Dust ◽  
Particle Formation ◽  
Aerosol Size Distribution ◽  
Urban Site ◽  
Climate Modelling ◽  
Special Importance ◽  
New Particle Formation ◽  
Mass Load

Abstract. A substantial fraction of the atmospheric aerosols originates from secondary new particle formation (NPF), where atmospheric vapours are transformed into particles that subsequently grow to larger sizes, affecting human health and the climate. In this study, we investigate aerosol size distributions at two stations located close to each other (∼ 20 km) but at different altitudes: urban (UGR; 680 m a.s.l., metres above sea level) and high-altitude remote (SNS; 2500 m a.s.l.) sites, both in the area of Granada, Spain, and part of AGORA observatory (Andalusian Global ObseRvatory of the Atmosphere). The analysis shows a significant contribution of nucleation mode aerosol particles to the total aerosol number concentration at both sites, with a contribution of 47 % and 48 % at SNS and UGR, respectively. Due to the important contribution of NPF events to the total aerosol number concentrations and their high occurrence frequency (> 70 %) during the study period, a detailed analysis of NPF events is done in order to get insight into the possible mechanisms and processes involved in NPF events at these contrastive sites. At SNS, NPF is found to be associated with the transport of gaseous precursors from lower altitudes by orographic buoyant upward flows. NPF events at the SNS site are always observed from the smallest measured sizes of the aerosol size distribution (4 nm), implying that NPF takes place in or in the vicinity of the high-altitude SNS station rather than being transported from lower altitudes. Although NPF events at the mountain site seem to be connected with those occurring at the urban site, growth rates (GRs) at SNS are higher than those at the UGR site (GR7−25 of 6.9 and 4.5 nm h−1 and GR4−7 of 4.1 and 3.6 nm h−1 at SNS and UGR, respectively). This fact could have special importance for the production of cloud condensation nuclei (CCN) and therefore for cloud formations which may affect regional/global climate, since larger GRs at mountain sites could translate to a larger survival probability of NPF particles reaching CCN sizes, due to the shorter time period needed for the growth. The analysis of sulfuric acid (H2SO4) shows that the contribution of H2SO4 is able to explain a minimal fraction contribution to the observed GRs at both sites (< 1 % and < 10 % for the 7–25 and 4–7 nm size ranges, respectively), indicating that other condensing vapours are responsible for the majority of particle growth, as well as the differing growth rates between the two sites. Results also show that the condensation sink (CS) does not play a relevant role in NPF processes at both sites and points to the availability of volatile organic compounds (VOCs) as one of the main factors controlling the NPF events at both sites. Finally, a closer analysis of the NPF events that were observed at the SNS site during a Saharan dust episode that occurred during the field campaign was carried out, evidencing the role of TiO2 and F2O3 together with VOCs in promoting new particle formation during this dust intrusion event. Although further investigation is needed to improve our understanding in this topic, this result suggests that climate effects of mineral dust and NPF are not disconnected from each other as it was commonly thought. Therefore, since mineral dust contributes to a major fraction of the global aerosol mass load, dust–NPF interaction should be taken into account in global aerosol-climate modelling for better climate change prediction.

scholarly journals Ancient versus modern mineral dust transported to high-altitude Alpine glaciers evidences Saharan sources and atmospheric circulation changes

2010 ◽  
Vol 10 (8) ◽  
pp. 20167-20191 ◽  
Author(s):  
F. Thevenon ◽  
M. Chiaradia ◽  
T. Adatte ◽  
C. Hueglin ◽  
J. Poté
Keyword(s):  
High Altitude ◽  
Mineral Dust ◽  
Saharan Dust ◽  
Ice Age ◽  
Anthropogenic Sources ◽  
Secondary Source ◽  
Research Station ◽  
Dust Deposition ◽  
Carbonaceous Particle ◽  
Airborne Dust

Abstract. Mineral dust aerosols collected during the years 2008/2009 at the high-altitude research station Jungfraujoch (46°33´, 7°59´; 3580 m a.s.l.) were compared to windblown mineral dust deposited at the Colle Gnifetti glacier (45°55´ N, 7°52´ E; 4455 m a.s.l.) over the last millennium. Insoluble dust has been characterized in terms of mineralogy, Sr and Nd isotopic ratios, and trace element composition. Results demonstrate that the Saharan origin of the airborne dust did not change significantly throughout the past. Backward trajectories analysis of modern analogs furthermore confirms that major dust sources are situated in the north-central to north-western part of the Saharan desert. By contrast, less radiogenic Sr isotopic compositions are associated with lower abundances of crustal elements during low rates of dust deposition, suggesting intercontinental transport of background dust rather than activation of a secondary source. Saharan dust mobilization and meridional advection of air masses were relatively reduced during the second part of the Little Ice Age (ca. 1690–1870), except within the greatest Saharan dust event deposited around 1780–1790. Higher dust deposition with larger mean grain size and Saharan fingerprint began ca. 20 years after the industrial revolution of 1850, suggesting that increased mineral dust transport over the Alps during the last century was primarily due to drier winters in North Africa and stronger spring/summer North Atlantic southwesterlies, rather than to direct anthropogenic sources. Meanwhile, increasing carbonaceous particle emissions from fossil fuels combustion combined to higher lead enrichment factor during the last century, point to concomitant anthropogenic sources of particulate pollutants reaching high-altitude European glaciers.

Atmospheric transport and deposition of trace elements to lake erie from Urban areas

1996 ◽  
Vol 33 (4-5) ◽  
pp. 259-265
Author(s):  
Gerald J. Keeler ◽  
Nicola Pirrone
Keyword(s):  
Trace Elements ◽  
Urban Areas ◽  
Lake Erie ◽  
Atmospheric Transport ◽  
Spatial And Temporal Variation ◽  
Deposition Flux ◽  
Emission Sources ◽  
Dry Deposition Flux ◽  
Ambient Concentration ◽  
Ambient Concentrations

A hybrid receptor-deposition (HRD) modeling approach was used to determine the spatial and temporal variation in the ambient concentration and dry deposition flux of trace elements on fine (&lt; 2.5 mm) and coarse (&gt; 2.5 mm) particulate matter over Lake Erie. Upper-air observations from the National Weather Service (NWS) and ambient concentrations measured at two sampling sites downwind of major emission sources in the Lake Erie basin were input to the model. An evaluation of the deposition flux of size-segregated trace elements to the lake during the over-water transport was performed. The average total (fine + coarse) deposition flux was 9.6 ng/m2-h for V, 70 ng/m2-h for Mn, 3.2 ng/m2-h for As, 4.2 ng/m2-h for Se, 10 ng/m2-h for Cd, and 43.3 ng/m2-h for Pb.

Reference values of trace elements in blood and/or plasma in adults living in Belgium

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Perrine Hoet ◽  
Chantal Jacquerye ◽  
Gladys Deumer ◽  
Dominique Lison ◽  
Vincent Haufroid
Keyword(s):  
Trace Elements ◽  
Reference Values ◽  
Inductively Coupled Plasma ◽  
Adult Population ◽  
A Priori ◽  
Selection Procedure ◽  
Anthropogenic Sources ◽  
Published Data ◽  
Reference Distribution ◽  
Belgian Population

AbstractObjectivesTrace elements (TEs) from natural and anthropogenic sources are ubiquitous. Essential or not, their relevance for human health and disease is constantly expanding. Biological monitoring is a widely integrated tool in risk assessment both in occupational and environmental settings. However, the determination of appropriate and accurate reference values in the (specific) population is a prerequisite for a correct interpretation of biomonitoring data. This study aimed at determining the reference distribution for TEs (Al, As, Sb, Be, Bi, Cd, Co, Cu, Mn, Hg, Mo, Ni, Pb, Se, Tl, Sn, V, Zn) in the blood and/or plasma of the adult population in Belgium.MethodsBlood and plasma samples were analyzed for 178 males and 202 females, recruited according to an a priori selection procedure, by inductively coupled plasma mass spectrometry (ICP-MS).ResultsReference values were established with high confidence for AsT, Cd, Cu, HgT, Mn, Mo, Pb, Sn, Se, Tl and Zn. Compared to previously published data in the Belgian population, a decreasing time trend is observed for Zn, Cd and Pb. Globally, the results also indicate that the current exposure levels to TEs in the Belgian population are similar to those from other recent national surveys.ConclusionsThese reference values and limits obtained through validated analytical and statistical methods will be useful for future occupational and/or environmental surveys. They will contribute to decision-making concerning both public health policies but also exposure assessments on an individual scale.

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