Chemical composition and source apportionment of PM10 at an urban background site in a high-altitude Latin American megacity (Bogota, Colombia)

The ratio of concentration of organic carbon and elemental carbon bound to particulate matter in ambient air: a global systematic review and meta-analysis

Four hundred and sixty-six references with 625 data reports were included in our study. The high frequency of ratio OC/EC for PM0.1 was observed in 3.92-5.93; PM1 in 1.08-3.08; PM2.5, 2.08-4.08; PM10 in 2.70-4.70 and TSP in 2.66-4.66. The rank order of areas based on the pooled concentration of OC bound to PM2.5 was traffic (17.893 µg/m3) > industrial (10.58 µg/m3) > urban (7.696 µg/m3) > rural (4.08 µg/m3). The rank order of areas based on the pooled (mean) concentration of EC in PM2.5 was traffic (17.893 µg/m3) > industrial (2.65 µg/m3) > Urban (1.48 µg/m3) > rural (1.06 µg/m3). The pooled concentrations of OC and EC bound to PM2.5 in traffic areas were higher than in other areas. Therefore, it is recommended that monitoring and effectively reducing concentration plans are carried out, especially in traffic areas.

Oxidative potential of particulate matter and its association to respiratory health endpoints in high-altitude cities in Bolivia

Exposure to particulate matter (PM) pollution is a significant health risk, driving the search for innovative metrics that more accurately reflect the potential harm to human health. Among these, oxidative potential (OP) has emerged as a promising health-based metric, yet its application and relevance across different environments remain to be further explored. This study, set in two high-altitude Bolivian cities, aims to identify the most significant sources of PM-induced oxidation in the lungs and assess the utility of OP in assessing PM health impacts. Utilizing two distinct assays, OPDTT and OPDCFH, we measured the OP of PM samples, while also examining the associations between PM mass, OP, and black carbon (BC) concentrations with hospital visits for acute respiratory infections (ARI) and pneumonia over a range of exposure lags (0-2 weeks) using a Poisson regression model adjusted for meteorological conditions. The analysis also leveraged Positive Matrix Factorization (PMF) to link these health outcomes to specific PM sources, building on a prior source apportionment study utilizing the same dataset. Our findings highlight anthropogenic combustion, particularly from traffic and biomass burning, as the primary contributors to OP in these urban sites. Significant correlations were observed between both OPDTT and PM2.5 concentration exposure and ARI hospital visits, alongside a notable association with pneumonia cases and OPDTT levels. Furthermore, PMF analysis demonstrated a clear link between traffic-related pollution and increased hospital admissions for respiratory issues, affirming the health impact of these sources. These results underscore the potential of OPDTT as a valuable metric for assessing the health risks associated with acute PM exposure, showcasing its broader application in environmental health studies.

Impact of altitude on the dosage of indoor particulates entering an individual's small airways

The complexity of indoor particulate exposure intensifies at higher altitudes owing to the increased lung capacity that residents develop to meet the higher oxygen demands. Altitude variations impact atmospheric pressure and alter particulate dynamics in ambient air and the human respiratory tract, complicating particulate inhalation. This study assessed the fraction of PM2.5 and PM10 entering small airways. This assessment covered an altitude range from 400 m above sea level to 3650 m, and an in vitro respiratory tract model was used. The experimental results confirmed that with increasing altitude, the penetration fractions of PM2.5 and PM10 significantly increased from 0.133 ± 0.031 and 0.141 ± 0.045 to 0.404 ± 0.159 and 0.353 ± 0.132, respectively. Additionally, the computational fluid dynamics simulation results revealed that among particles with sizes of 0.1 to 10 µm, the 7.5-μm particles exhibited the most substantial reduction in deposition in the upper airway, displaying a decrease of 6.27%. Our findings underscore the health risks faced by low-altitude residents during acclimatization to higher altitudes, as they experience heightened exposure to particulate matter sources.

Intra-urban variability of long-term exposure to PM2.5 and NO2 in five cities in Colombia

Rapidly urbanizing cities in Latin America experience high levels of air pollution which are known risk factors for population health. However, the estimates of long-term exposure to air pollution are scarce in the region. We developed intraurban land use regression (LUR) models to map long-term exposure to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) in the five largest cities in Colombia. We conducted air pollution measurement campaigns using gravimetric PM2.5 and passive NO2 sensors for 2 weeks during both the dry and rainy seasons in 2021 in the cities of Barranquilla, Bucaramanga, Bogotá, Cali, and Medellín, and combined these data with geospatial and meteorological variables. Annual models were developed using multivariable spatial regression models. The city annual PM2.5 mean concentrations measured ranged between 12.32 and 15.99 µg/m3 while NO2 concentrations ranged between 24.92 and 49.15 µg/m3. The PM2.5 annual models explained 82% of the variance (R2) in Medellín, 77% in Bucaramanga, 73% in Barranquilla, 70% in Cali, and 44% in Bogotá. The NO2 models explained 65% of the variance in Bucaramanga, 57% in Medellín, 44% in Cali, 40% in Bogotá, and 30% in Barranquilla. Most of the predictor variables included in the models were a combination of specific land use characteristics and roadway variables. Cross-validation suggests that PM2.5 outperformed NO2 models. The developed models can be used as exposure estimate in epidemiological studies, as input in hybrid models to improve personal exposure assessment, and for policy evaluation.

Spatial distributions of PM10-bound metal elements in the central part of western Taiwan and their potential emission sources and the carcinogenic health risks

This study aimed to investigate the spatial distribution of metal elements in PM10 and their potential sources and associated health risks over a period of two years in eight locations in the central part of western Taiwan. The study revealed that the mass concentration of PM10 and the total mass concentration of 20 metal elements in PM10 were 39.0 μg m-3 and 4.74 μg m-3, respectively, with total metal elements accounting for approximately 13.0% of PM10. Of the total metal elements, 95.6% were crustal elements (Al, Ca, Fe, K, Mg, and Na), with trace elements (As, Ba, Cd, Cr, Co, Cu, Ga, Mn, Ni, Pb, Sb, Se, V, and Zn) contributing only 4.4%. Spatially, the inland areas exhibited higher PM10 concentrations due to lee-side topography and low wind speeds. In contrast, the coastal regions exhibited higher total metal concentrations because of the dominance of crustal elements from sea salt and crustal soil. Four primary sources of metal elements in PM10 were identified as sea salt (58%), re-suspended dust (32%), vehicle emissions and waste incineration (8%), and industrial emissions and power plants (2%). The positive matrix factorization (PMF) analysis results indicated that natural sources like sea salt and road dust contributed up to 90% of the total metal elements in PM10, while only 10% was attributed to human activities. The excess cancer risks (ECRs) associated with As, Co, and Cr(VI) were greater than 1 × 10-6, and the total ECR was 6.42 × 10-5. Although only 10% of total metal elements in PM10 came from human activities, they contributed to 82% of the total ECR.

Source apportionment of PM10 and health risk assessment related in a narrow tropical valley. Study case: Metropolitan area of Aburrá Valley (Colombia)

This study investigates spatio-temporal variations of PM10 mass concentrations and associated metal(oid)s, δ13C carbon isotope ratios, polycyclic aromatic hydrocarbons (PAHs), total organic carbon (TOC) and equivalent black carbon (eBC) concentrations over a half year period (from March 2017 to October 2017) in two residential areas of Medellín (MED-1 and MED-2) and Itagüí municipality (ITA-1 and ITA-2) at a tropical narrow valley (Aburrá Valley, Colombia), where few data are available. A total of 104 samples were analysed by using validated analytical methodologies, providing valuable data for PM10 chemical characterisation. Metal(oid)s concentrations were measured by inductively coupled plasma mass spectrometry (ICP-MS) after acid digestion, and PAHs concentrations were measured by Gas Chromatography-Mass Spectrometry (GC-MS) after Pressurised Hot Water Extraction (PHWE) and Membrane Assisted Solvent Extraction (MASE). Mean PM10 mass concentration ranged from 37.0 µg m-3 to 45.7 µg m-3 in ITA-2 and MED-2 sites, respectively. Al, Ca, Mg and Na (from 6249 ng m-3 for Mg at MED-1 site to 10,506 ng m-3 for Ca at MED-2 site) were the major elements in PM10 samples, whilst As, Be, Bi, Co, Cs, Li, Ni, Sb, Se, Tl and V were found at trace levels (< 5.4 ng m-3). Benzo[g,h,i] perylene (BghiP), benzo[b + j]fluoranthene (BbjF) and indene(1,2,3-c,d)pyrene (IcdP) were the most profuse PAHs in PM10 samples, with average concentrations of 0.82-0.86, 0.60-0.78 and 0.47-0.58 ng m-3, respectively. Results observed in the four sampling sites showed a similar dispersion pattern of pollutants, with temporal fluctuations which seems to be associated to the meteorology of the valley. A PM source apportionment study were carried out by using the positive matrix factorization (PMF) model, pointing to re-suspended dust, combustion processes, quarry activity and secondary aerosols as PM10 sources in the study area. Among them, combustion was the major PM10 contribution (accounting from 32.1 to 32.9% in ITA-1 and ITA-2, respectively), followed by secondary aerosols (accounting for 13.2% and 23.3% ITA-1 and MED-1, respectively). Finally, a moderate carcinogenic risk was observed for PM10-bound PAHs exposure via inhalation, whereas significant carcinogenic risk was estimated for carcinogenic metal(oid)s exposure in the area during the sampling period.

Spatio-temporal analysis of PM2.5 and policies in Northwestern South America

This paper analyzes the spatio-temporal variations, and exceedances of the PM_2.5 concentrations in Northwestern South America at different scales to assess the implemented policies and identify the involved phenomena. Through reanalysis and ground-based data, we found that high PM_2.5 levels in most cities of the region are caused by wildfires and local emissions, including the capital cities of Venezuela, Ecuador, Colombia, and Panamá. In-situ measurements suggest that the majority of the cities comply with the local but not with the WHO guidelines, indicating that local annual limits should be more restrictive. Two peaks in the daily variations of PM_2.5 (related to vehicle emissions) and also a steeper decrease around noon (associated with an increase in wind speed and in the boundary layer height) were identified. The trend-analysis shows that Bogotá and Medellín have a decreasing PM_2.5 annual-trend (between -0.8μgm^-3 and -1.7μgm^-3) that corresponds to effective policies. In contrast, Cali has a positive annual-trend (0.8μgm^-3) most likely because of Short-Range Transport produced by a northerly-flow from a highly polluted neighboring city, which also affects Cali's PM_2.5 diurnal cycle, or by local-dynamics. The exceedances show that the policies are working on an annual but not at a daily time-scale. These results serve as a first input for additional studies, with the aim of gaining a better understanding of the contaminant before adapting current policies or implementing new policies and measures that need to include a joint international, regional, and inter-city efforts regarding pollution transport.

Short-Term Associations between PM10 and Respiratory Health Effects in Visby, Sweden

The old Swedish city Visby, located on the island Gotland, has, for several years, reported higher PM₁₀ concentrations than any other city in Sweden. In Visby, local limestone is used, both in road paving and as sand used for anti-slip measures, resulting in a clear annual pattern of PM₁₀ with the highest concentrations during winter/spring when studded tires are allowed. This study analyzes the short-term associations between PM₁₀ and daily number of patients with acute respiratory problems (ICD–10 diagnoses: J00–J99) seeking care at the hospital or primary healthcare units in Visby during the period of 2013–2019. The daily mean of PM₁₀ was on average 45 µg m⁻³ during winter/spring and 18 µg m⁻³ during summer/autumn. Four outcome categories were analyzed using quasi-Poisson regression models, stratifying for period and adjusting for calendar variables and weather. An increase in respiratory visits was associated with increasing concentrations in PM₁₀ during the summer/autumn period, most prominent among children, where asthma visits increased by 5% (95% CI: 2–9%) per 10 µg m⁻³ increase in PM₁₀. For the winter/spring period, no significant effects were observed, except for the diagnose group ‘upper airways’ in adults, where respiratory visits increased by 1% (95% CI: 0.1–1.9%) per 10 µg m⁻³ increase. According to the results, limestone in particles seem to be relatively harmless at the exposure concentrations observed in Visby, and this is in line with the results from a few experimental and occupational studies.

Source Apportionment of Atmospheric PM10 in Makkah Saudi Arabia by Modelling Its Ion and Trace Element Contents with Positive Matrix Factorization and Generalised Additive Model

In this paper, the emission sources of PM10 are characterised by analysing its trace elements (TE) and ions contents. PM10 samples were collected for a year (2019−2020) at five sites and analysed. PM10 speciated data were analysed using graphical visualization, correlation analysis, generalised additive model (GAM), and positive matrix factorization (PMF). Annual average PM10 concentrations (µg/m3) were 304.68 ± 155.56 at Aziziyah, 219.59 ± 87.29 at Misfalah, 173.90 ± 103.08 at Abdeyah, 168.81 ± 82.50 at Askan, and 157.60 ± 80.10 at Sanaiyah in Makkah, which exceeded WHO (15 µg/m3), USEPA (50 µg/m3), and the Saudi Arabia national (80 µg/m3) annual air quality standards. A GAM model was developed using PM10 as a response and ions and TEs as predictors. Among the predictors Mg, Ca, Cr, Al, and Pb were highly significant (p < 0.01), Se, Cl, and NO2 were significant (p < 0.05), and PO4 and SO4 were significant (p < 0.1). The model showed R-squared (adj) 0.85 and deviance explained 88.1%. PMF identified four main emission sources of PM10 in Makkah: (1) Road traffic emissions (explained 51% variance); (2) Industrial emissions and mineral dust (explained 27.5% variance); (3) Restaurant and dwelling emissions (explained 13.6% variance); and (4) Fossil fuel combustion (explained 7.9% variance).

Impact of different sources on the oxidative potential of ambient particulate matter PM10 in Riyadh, Saudi Arabia: A focus on dust emissions

In this study, we employed Principal Component Analysis (PCA) and Multi-Linear Regression (MLR) to identify the most significant sources contributing to the toxicity of PM10 in the city center of Riyadh. PM10 samples were collected using a medium-volume air sampler during cool (December 2019-March 2020) and warm (May 2020-August 2020) seasons, including dust and non-dust events. The collected filters were analyzed for their chemical components (i.e., water-soluble ions, metals, and trace elements) as well as oxidative potential and elemental and organic carbon (EC/OC) contents. Our measurements revealed comparable extrinsic oxidative potential (P-value = 0.30) during the warm (1.2 ± 0.1 nmol/min-m3) and cool (1.1 ± 0.1 nmol/min-m3) periods. Moreover, we observed higher extrinsic oxidative potential of PM10 samples collected during dust events (~30% increase) compared to non-dust samples. Our PCA-MLR analysis identified soil and resuspended dust, secondary aerosol (SA), local industrial activities and petroleum refineries, and traffic emissions as the four sources contributing to the ambient PM10 oxidative potential in central Riyadh. Soil and resuspended dust were the major source contributing to the oxidative potential of ambient PM10, accounting for 31% of the total oxidative potential. Secondary aerosols (SA) were the next important source of PM10 toxicity in the area as they contributed to about 20% of the PM10 oxidative potential. Results of this study revealed the major role of soil and resuspended road dust on PM10 toxicity and can be helpful in adopting targeted air quality policies to reduce the population exposure to PM10.

Poor regulation implications in a low and middle income country based on PAH source apportionment and cancer risk assessment

Ambient particle-bound polycyclic aromatic hydrocarbons (PAHs) were collected for one year at an urban background site, and spatially and temporally compared to yearly averages in three coastal cities in Lebanon. The samples were quantified using gas chromatography-mass spectrometry (GC-MS) and source apportioned with an optimized robust method using positive matrix factorization (PMF). Three major sources were found to contribute to PAH emissions at the urban background site, namely, traffic (48%), diesel generators (23%), and incineration (29%). The cancer risk was found higher than what was measured at the same site in previous years with an increase of 35%. Improper regulations of the sources (incineration, power plant, diesel generators and traffic) identified in the different sites resulted in PAH intraurban variability. It is essential to study the chemical components of particulate matter (PM) in order to assess toxicity. In particular, particle-bound PAHs and their oxidation products are known for their carcinogenicity as well as their persistence in the atmosphere, which facilitate their transport to new locations. In the absence of law enforcement, unregulated sources and their total contribution to ambient PAHs present a major health risk. This calls for the attention of development funding agencies and their need to implement sustainable "carbon-free" funding strategies in support of urban development of low and middle-income countries (LMICs).

Effects of deployment of electric vehicles on air quality in the urban area of Turin (Italy)

This study aims to evaluate and quantify the environmental, health, and economic benefits due to the penetration of electric vehicles in the fleet composition by replacing conventional vehicles in an urban area. This study has been performed for the city of Turin, where road transport represents one of the main primary emission sources. Air pollution data were evaluated by ADMS-Roads, the flow traffic data used for simulation come from a real-time monitoring. Instead, statistics on mortality and hospitalizations due to cardiovascular and respiratory diseases were collected from the regional health information system and the National Health Institute and implemented in the BenMap software to evaluate the health and economic impacts. In both cases, two scenarios to evaluate the annual benefits of reducing PM₁₀, PM_2.5 and NO₂ were used: reduction to the levels gained by the assumptions of 2025 and 2030 Scenario and the PM₁₀, PM_2.5 and NO₂ concentrations were considered for evaluating short-term and long-term effects. The analysis performed doesn't include background pollution levels, i.e. the concentrations percentage reductions are only related to the local contribution, therefore derived from the contribution only of traffic source. The results show that fleet electrification has a potential benefit for concentrations reduction in comparison to the base Scenario, especially related to NO₂, less for PM₁₀ and PM_2.5. Regarding 2025 Scenario (4 % (passenger car) and 5 % (light-duty vehicles) electric vehicles), reductions of 52 % of NO2, 35 % of PM10 and 49 % of PM2.5 are observed. Meanwhile, as regards 2030 Scenario reductions of 87 % of NO2, 36 % of PM10 and 50 % of PM2.5 are reached. Also, in terms of social costs a decrease of 47 % for the 2025 Scenario and 66 % for the 2030 Scenario in comparison to the base Scenario is arise.

Spatial Distribution and Chemical Composition of Road Dust in Two High-Altitude Latin American Cities

Road dust (RD) resuspension is one of the main sources of particulate matter in cities with adverse impacts on air quality, health, and climate. Studies on the variability of the deposited PM10 fraction of RD (RD10) have been limited in Latin America, whereby our understanding of the central factors that control this pollutant remains incomplete. In this study, forty-one RD10 samples were collected in two Andean cities (Bogotá and Manizales) and analyzed for ions, minerals, and trace elements. RD10 levels varied between 1.8–45.7 mg/m2, with an average of 11.8 mg/m2, in Bogotá and between 0.8–26.7 mg/m2, with an average of 5.7 mg/m2, in Manizales. Minerals were the most abundant species in both cities, with a fraction significantly larger in Manizales (38%) than Bogotá (9%). The difference could be explained mainly by the complex topography and the composition of soil derived from volcanic ash in Manizales. The volcanic activity was also associated with SO4−2 and Cl−. Enrichment factors and principal component analysis were conducted to explore potential factors associated to sources of RD10. Elements such as Cu, Pb, Cr, Ni, V, Sb, and Mo were mainly associated with exhaust and non-exhaust traffic emissions.

Arsenic and SO2 hotspot in South-Eastern Europe: An overview of the air quality after the implementation of the flash smelting technology for copper production

This extensive study considered the air pollution data after the flash smelting technology for copper production had become fully operational. The assessment of the air quality after the implementation was significantly important, since the modernisation was necessary for reducing the environmental contamination in one of the most polluted regions in South-Eastern Europe. The concentrations of SO₂, PM₁₀ and toxic elements (As, Pb, Cd, Ni) in PM₁₀ samples were monitored at different sites, with respect to the copper smelter, in the period 2016-2019. The air quality evaluation was performed concerning the corresponding limit and target values defined by the Serbian and European legislation, as well as the World Health Organization Air Quality Guidelines (WHO AQG). The measured SO₂ concentrations indicated frequent exceedances of the defined daily and annual limit values, at both national and European level. Although exceedances were not as pronounced as in the period before the implementation of the new technology, the episodes of extreme air pollution with SO₂ persisted on the daily basis. The maximum daily SO₂ concentration of 2125 μg m^-3 was more than 100 times higher compared to the WHO AQG, but lower compared to the period before the implementation of the flash smelting technology. The air quality considering PM₁₀ and especially As levels in PM₁₀ samples was notably poorer after the modernisation. The annual target value for As, defined by the European and Serbian Regulation, was exceeded at all the measuring sites, with maximum exceedance of more than 90 times at the suburban site during 2019. The frequent exceedances of the corresponding annual limit and target values were also denoted for Pb and Cd in PM₁₀ samples. The analysed data emphasised that the Bor area could still be characterised as an environmental hotspot in Serbia and beyond.

Air quality modeling to inform pollution mitigation strategies in a Latin American megacity

Poor air quality disproportionally impacts cities in low- and middle-income countries. In Bogotá, Colombia, a metropolitan area with over 10 million inhabitants, fine particulate matter (PM_2.5) levels regularly exceed air quality guidelines, leading to detrimental effects on health. Although there is public interest to improve the city's air quality, the main sources of PM_2.5 pollution have not been clearly identified and the use of modeling for policy development in Bogotá has been limited. Here, we apply a modeling framework based on the Community Multiscale Air Quality Modeling System (CMAQ) to conduct seasonal simulations of air pollution in Bogotá and reveal the emissions sectors with the largest contributions to PM_2.5. Based on these results, we project and compare the air quality benefits of potential pollution mitigation strategies focused on these sources. The analysis finds that resuspended dust from unpaved roads is the largest local source of PM_2.5 and can contribute over 30% of seasonally-averaged concentration across the city. Vehicles, industrial activity, and unpaved road dust combined are responsible for over 60% of PM_2.5 pollution in Bogotá. A scenario analysis shows that paving roads can lead to PM_2.5 decreases of nearly 10 μg/m³ by 2030 in some areas of the city, but air quality will deteriorate significantly over others in the absence of additional emissions control measures. Mitigation strategies designed to target the sectors with the largest contributions to PM_2.5, including road cleaning systems, controls for industrial point sources, cleaner transportation fuels, and updated vehicle fleets, can largely avert projected increases in concentrations, although the impacts of different approaches vary throughout the city. This study is the first to use a comprehensive model to determine sector contributions to air pollution and inform potential emissions control policies in Bogotá, demonstrating an approach to guide pollution management in developing cities facing comparable challenges.

Spatial distribution and sources of potentially toxic elements in road dust and its PM10 fraction of Moscow megacity

For the first time, the contents of potentially toxic elements (PTEs) in road dust and in its PM₁₀ fraction were studied in Moscow from June 09 to July 30, 2017 on roads with different traffic intensities, inside courtyards with parking lots, and on pedestrian walkways in parks. The contents of PTEs in road dust and PM₁₀ fraction were analyzed by ICP-MS and ICP-AES. The main pollutants of road dust and its PM₁₀ fraction included Sb, Zn, W, Sn, Bi, Cd, Cu, Pb, and Mo. PM₁₀ was a major carrier of W, Bi, Sb, Zn, Sn (accounts for >65% of their total contents in road dust); Cu (>50%); and Cd, Pb, Mo, Co, Ni (30-50%). PM₁₀ fraction was 1.2-6.4 times more polluted with PTEs than bulk samples. Resuspension of roadside soil particles accounted for 34% of the mass of PTEs in road dust and for 64% in the PM₁₀ fraction. Other important sources of PTEs were non-exhaust vehicles emissions (~ 20% for dust and ~14% for PM₁₀) and industrial emissions (~20% and ~6%). The road dust and PM₁₀ particles were most contaminated in the central part of the city due to the large number of cars and traffic congestions. Local anomalies of individual PTEs were observed near industrial zones mainly in the west, south, and southeast of Moscow. In the yards of residential buildings the total enrichment of road dust and PM₁₀ with PTEs was only 1.1-1.5 times lower than that on major roads which poses a serious danger to the population spending a significant part of their lives in residential areas. The spatial pattern of the PTEs distribution in road dust and its PM₁₀ fraction should assist in more efficient planning of washing and mechanical cleaning of the road surface from dust to minimize the risk to public health.

Assessment of metals in PM10 filters and Araucaria heterophylla needles in two areas of Quito, Ecuador

The reliability of Araucaria heterophylla needles as a biomonitor was evaluated by analyzing the concentration of metals in PM₁₀ filters and in Araucaria heterophylla needles. The sampling campaign was carried out at two sites in the city of Quito, Ecuador, in 2017–2019. Concentrations of Cr, Cu, K, Mn, Pb, Zn, Ca, Fe, Al and Mg were determined in PM₁₀ filters and in Araucaria heterophylla needles using an Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES). The annual mean concentrations of PM₁₀ ranged between 24.9 and 26.3 μg m⁻³, exceeding the limit established by the World Health Organization (20 μg m⁻³). Statistical analyses, performed for the PM₁₀ filters, showed that dust resuspension and anthropogenic activities were important sources for PM₁₀ emissions in the city. Metals related to natural emissions (Ca, Mg, K, Al and Fe) dominated in both types of samples, while the minor metals were those related to anthropogenic emissions (Zn, Cu, Cr and Pb). The former were positively associated with the needle samples, while the latter were associated with PM₁₀ filters. This work not only improved scientific knowledge on the concentrations of PM₁₀ and metals in the Andean city of Quito, but also greatly contributed to the progress of research on the use of Araucaria heterophylla needles as a biomonitor.

Evaluation of factors influencing road dust loadings in a Latin American urban center

Vehicle non-exhaust emissions are a major component of particle matter, including the direct wear of tires, brakes, road, and the resuspension of deposited particles. It is suggested that resuspended PM (RPM) emissions can be at the same magnitude or even larger than combustion emissions in urban centers. Factors affecting RPM can be included in four categories: road characteristics, traffic condition, land use, and meteorology. In order to study and evaluate these influencing factors, road dust less than 10 micrometers (RD10) was collected in 41 sites across Bogotá. The sampling points had diverse characteristics. RD10 levels varied between 1.0 and 45.8 mg/m² with an average of 8.9 ± 8.4 mg/m². Lower RD10 values were observed when vegetation density was high, pavement condition good, driving speeds fast and construction activities absent. On the contrary, RD10 increased under heavy-duty traffic influence and dry conditions. Among dust mitigation measures, management of land-use variables could be as important as traffic control and road maintenance. Implications: This study documented for the first time in Latin America dust loadings less than 10 micrometers, information that can be used to estimate resuspended particle matter emissions in the region. The influence of meteorology, traffic characteristics, road condition, and land-use variables was analyzed and quantified. The management of land-use variables could be as important as traffic control and road maintenance for road dust mitigation. Further research interests are discussed.

Analysis of incidence of air quality on human health: a case study on the relationship between pollutant concentrations and respiratory diseases in Kennedy, Bogotá

Thousands of deaths associated with air pollution each year could be prevented by forecasting the behavior of factors that pose risks to people's health and their geographical distribution. Proximity to pollution sources, degree of urbanization, and population density are some of the factors whose spatial distribution enables the identification of possible influence on the presence of respiratory diseases (RD). Currently, Bogotá is among the cities with the poorest air quality in Latin America. Specifically, the locality of Kennedy is one of the zones in the city with the highest recorded concentration levels of local pollutants over the last 10 years. From 2009 to 2016, there were 8619 deaths associated with respiratory and cardiovascular diseases in the locality. Given these characteristics, this study set out to identify and analyze the areas in which the primary socioeconomic and environmental conditions contribute to the presence of symptoms associated with RD. To this end, information collected in field by performing georeferenced surveys was analyzed through geostatistical and machine learning tools which carried out cluster and pattern analyses. Random forests and AdaBoost were applied to establish hot spots where RD could occur, given the conjugation of predictor variables in the micro-territory. It was found that random forests outperformed AdaBoost with 0.63 AUC. In particular, this study's approach applies to densely populated municipalities with high levels of air pollution. In using these tools, municipalities can anticipate environmental health situations and reduce the cost of respiratory disease treatments.

Spatial distribution of fine and coarse particulate matter during a southwest monsoon in Peninsular Malaysia

This study aimed to determine the spatial distribution of PM_2.5 and PM₁₀ collected in four regions (North, Central, South and East Coast) of Peninsular Malaysia during the southwest monsoon. Concurrent measurements of PM_2.5 and PM₁₀ were performed using a high volume sampler (HVS) for 24 h (August to September 2018) collecting a total of 104 samples. All samples were then analysed for water soluble inorganic ions (WSII) using ion chromatography, trace metals using inductively coupled plasma-mass spectroscopy (ICP-MS) and polycyclic aromatic hydrocarbon (PAHs) using gas chromatography-mass spectroscopy (GC-MS). The results showed that the highest average PM_2.5 concentration during the sampling campaign was in the North region (33.2 ± 5.3 μg m^-3) while for PM₁₀ the highest was in the Central region (38.6 ± 7.70 μg m^-3). WSII recorded contributions of 22% for PM_2.5 and 20% for PM₁₀ mass, with SO₄^2- the most abundant species with average concentrations of 1.83 ± 0.42 μg m^-3 (PM_2.5) and 2.19 ± 0.27 μg m^-3 (PM₁₀). Using a Positive Matrix Factorization (PMF) model, soil fertilizer (23%) was identified as the major source of PM_2.5 while industrial activity (25%) was identified as the major source of PM₁₀. Overall, the studied metals had hazard quotients (HQ) value of <1 indicating a very low risk of non-carcinogenic elements while the highest excess lifetime cancer risk (ELCR) was recorded for Cr VI in the South region with values of 8.4E-06 (PM_2.5) and 6.6E-05 (PM₁₀). The incremental lifetime cancer risk (ILCR) calculated from the PAH concentrations was within the acceptable range for all regions.

PM10 spatial distribution and metals speciation study in the Bilbao metropolitan area during the 2017-2018 period

Speciation of respirable particles is becoming increasingly important from an epidemiological and analytical point of view to determine the potential effects of air pollution on human health. For this reason, current laws and analytical sampling methods focus on particle size, as it turns out to be the main factor for the greater or lesser penetration into the airways. In this sense, particles of less than 10 μm in diameter (<10 μm), referred to as PM₁₀, are the particles that have a higher capacity for access to the respiratory tract and, therefore, more significant effect on them. In this sense, one of the most important factors that have a key role in the PM₁₀ atmospheric pollution effect is the dispersion effect with the direct influence of natural effects such as wind, rain, topography apart from others. In this work, PM₁₀ data extracted from the Basque Government environmental stations (19 sampling points) in the Biscay province (Basque Country, north of Spain) were combined with the results obtained from the use of self-made passive samplers (SMPS) in the same sampling points areas and subsequently, the sample analysis with a non-invasive elemental technique (Scanning Electron Microscope coupled to Energy Dispersive X-ray Spectrometry) was carried out. Thanks to this methodology, it was possible to determine a wide variety of metals in PM₁₀ such as Al, Fe, Cr, Ni, Pb, Zn, Ti, etc. Most of them present as oxides and others as part of natural aggregations such as quartz, aluminosilicates, phosphates etc.

Estimating the air quality and health impacts of biomass burning in northern South America using a chemical transport model

Biomass burning (BB) emissions significantly deteriorate air quality in many regions worldwide, impact human health and perturbing Earth's radiation budget and climate. South America is one of largest contributors to BB emissions globally. After Amazonia, BB emissions from open and agricultural fires of Northern South America (NSA) are the most significant. Recent evidence shows a strong correlation between fire counts in NSA and Brown Carbon in some Colombian cities, suggesting a substantial seasonal contribution of regional BB sources to air pollution levels in the densely populated areas of NSA. In this work we use the atmospheric regional chemical transport model WRF-Chem to assess the contribution of open BB events to pollutant concentration and to estimate potential health impacts associated with wildfire events in NSA. Three nested domains are used to simulate atmospheric composition in the Northern part of South America and the Caribbean. Simulations included biogenic and anthropogenic emissions from a global emission inventory merged with local emissions for the city of Bogotá. Two modelling scenarios were considered, a base case without BB emissions (NO_FIRE) and a sensitivity scenario with BB emissions. Simulations were carried out for periods of strong BB activity in NSA. In the NO_FIRE scenario, aerosol concentrations are unrealistically low. When BB emissions are is included background PM_2.5 concentrations increase 80%. The increment in aerosol concentrations is mainly driven by Secondary Organic Aerosols. In the case of Bogotá, the most densely populated city in the domain, monthly mean increase in PM_2.5 is 3.3 μg m^-3 and 4.3 ppb for O₃. Modeled meteorological and air pollution fields are in better agreement with observations when high spatial resolution (3 × 3 km) is used in the simulations. The total estimated short-term all-cause mortality associated to BB during February in the region is 171 cases, 88 PM_2.5-related and 83 O₃-related mortality.

Seasonal variations in PM10 inorganic composition in the Andean city

Particulate matter (PM) is one of the key pollutants causing health risks worldwide. While the preoccupation for increased concentrations of these particles mainly depends on their sources and thus chemical composition, some regions are yet not well investigated. In this work the composition of chemical elements of atmospheric PM₁₀ (particles with aerodynamic diameters ≤ 10 µm), collected at the urban and suburban sites in high elevation tropical city, were chemically analysed during the dry and wet seasons of 2017-2018. A large fraction (~ 68%) of PM₁₀ composition in Quito, Ecuador is accounted for by water-soluble ions and 16 elements analysed using UV/VIS spectrophotometer and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). Hierarchical clustering analysis was performed to study a correlation between the chemical composition of urban pollution and meteorological parameters. The suburban area displays an increase in PM₁₀ concentrations and natural elemental markers during the dry (increased wind intensity, resuspension of soil dust) season. Meanwhile, densely urbanized area shows increased total PM₁₀ concentrations and anthropogenic elemental markers during the wet season, which may point to the worsened combustion and traffic conditions. This might indicate the prevalence of cardiovascular and respiratory problems in motorized areas of the cities in the developing world.

Dissolved and Suspended Forms of Metals and Metalloids in Snow Cover of Megacity: Partitioning and Deposition Rates in Western Moscow

Concentrations and ratio of dissolved and suspended forms of metals and metalloids (MMs) in snow cover and their deposition rates from the atmosphere in the western part of Moscow were studied. Forms of MMs were separated using a filter with pore diameter of 0.45 μm; their concentrations were measured by ICP-MS and ICP-AES methods. Anthropogenic impact in Moscow caused a significant increase in dust load (2–7 times), concentration of solid particles in snow cover (2–5 times), and mineralization of snow meltwater (5–18 times) compared to the background level. Urban snow contains Sn, Ti, Bi, Al, W, Fe, Pb, V, Cr, Rb, Mo, Mn, As, Co, Cu, Ba, Sb, Mg mainly in suspended form, and Ca and Na in dissolved form. The role of suspended MMs in the city significantly increases compared to the background region due to high dust load, usage of de-icing salts, and the change of acidic background conditions to alkaline ones. Anthropogenic emissions are the main sources of suspended Ca, W, Co, V, Sr, Ti, Mg, Na, Mo, Zn, Fe, Sb, and Cu in the snow cover of traffic zone. These elements’ concentrations in roadside snow cover exceed the background values more than 25 times. The highest concentrations and deposition rates of MMs in the snow of Moscow are localized near the large and medium roads.

Hazardous trace elements in thoracic fraction of airborne particulate matter: Assessment of temporal variations, sources, and health risks in a megacity

The deleterious health effects of thoracic fractions seem to be more related to the chemical composition of the particles than to their mass concentration. The presence of hazardous materials in PM₁₀ (e.g., heavy metals and metalloids) causes risks to human health. In this study, twelve trace elements (Cd, Cr, Pb, Zn, Cu, Ni, Sn, Ba, Co, As, V, and Sb) in 315 samples of ambient PM₁₀ were analyzed. The samples were collected at an urban background site in a Latin American megacity (Bogota, Colombia) for one year. The concentrations and temporal variabilities of these elements were examined. According to the results, Cu (52 ng/m³), Zn (44 ng/m³), Pb (25 ng/m³), and Ba (20 ng/m³) were the traces with the highest concentrations, particularly during the dry season (January to March), which was characterized by barbecue (BBQ) charcoal combustion and forest fires. In addition, the differences between the results of weekdays and weekends were identified. The determined enrichment factor (EF) indicated that Zn, Pb, Sn, Cu, Cd, and Sb mainly originated from anthropogenic sources. Moreover, a speciation analysis of inorganic Sb (EF > 300) was conducted, which revealed that Sb(V) was the main Sb species in the PM₁₀ samples (>80%). Six causes for the hazardous elements were identified based on the positive matrix factorization (PMF) model: fossil fuel combustion and forest fires (60%), road dust (19%), traffic-related emissions (9%), copper smelting (8%), the iron and steel industry (2%), and an unidentified industrial sector (2%). Furthermore, a health risk assessment of the carcinogenic elements was performed. Accordingly, the cancer risk of inhalation exposure to Co, Ni, As, Cd, Sb(III), and Pb was negligible for children and adults at the sampling site. For adults, the adjusted Cr(VI) level was slightly higher than the minimal acceptable risk level during the study period (1.4 × 10^-6).

Characteristics and temporal variations of organic and elemental carbon aerosols in PM1 in Changchun, Northeast China

The present study offers the first evaluation of organic and elemental carbon (OC and EC) of submicron (PM₁) fraction in Changchun (Northeast China) during a year-long sampling period (October 24, 2016 to October 23, 2017). More than 288 PM₁ (particulate matter with an aerodynamic diameter of less than 1 μm) samples were collected. The PM₁ concentrations ranged from 3.78 to 451.08 μg·m^-3, with an average of 57.73 μg·m^-3, which was 1.65 times higher than the Chinese National Standard II. Following the concept of the well-known IMPROVE algorithm, OC and EC values were obtained. The OC values ranged from 1.18 to 82.54 μg∙m^-3, and the EC values were from 0.30 to 14.19 μg∙m^-3. Total carbon (TC = EC + OC) constituted 9.11-40.35% of the total PM₁ mass, and OC dominated over EC. The average OC/EC ratio was 4.78, which implied a low percentage for vehicles and a high contribution of coal and biomass consumption to PM₁. Among OC, the annual primary organic carbon (POC) value was 7.69 μg∙m^-3, accounting for 63% of the OC, while secondary organic carbon (SOC) contributed 37% with 4.12 μg∙m^-3. Among EC, CHAR (EC1) dominated over SOOT (EC2 + EC3), and the CHAR/SOOR ratio ranged from 2.91 to 28.55. The results of the OC and EC values as well as the OC/EC and CHAR/SOOT ratios suggest that possible sources of PM₁ include vehicles, coal burning, cooking, and biomass burning.

Physicochemical characterization and sources of the thoracic fraction of road dust in a Latin American megacity

Road dust has been identified as one of the main sources of outdoor PM₁₀ in Bogota (a Latin American megacity), but there are no studies that have analyzed the physicochemical characteristics and origins of its respirable fraction. A characterization of inorganic compounds (water soluble ions, major and trace elements, organic and elemental carbon) and an analysis of source contributions to the PM₁₀ fraction of road dust were carried out in this study. A total of twenty road dust samples, selected from representative industrial, residential and commercial areas, were swept and resuspended to obtain the thoracic fraction. Size distribution by laser diffraction and individual particle morphology by Scanning Electron Microscopy were also evaluated. The data obtained revealed that the volume (%) of thoracic particles was higher in samples from industrial zones where heavy vehicular traffic, industrial emissions and deteriorated pavements predominated. Crustal elements were the most abundant species, accounting for 49-62% of the thoracic mass, followed by OC (13-29%), water-soluble ions (1.4-3.8%), EC (0.8-1.9%) and trace elements (0.2-0.5%). The Coefficient of Divergence was obtained to identify the spatial variability of the samples. A source apportionment analysis was carried out considering the variability of chemical profiles, enrichment factors and ratios of Fe/Al, K/Al, Ca/Al, Ti/Al, Cu/Sb, Zn/Sb, OC/TC and OC/EC. By means of a PCA analysis, five components were identified, including local soils and pavement erosion (63%), construction and demolition activities (13%), industrial emissions (6%), brake wear (5%) and tailpipe emissions (4%). These components accounted for 91% of the total variance. The results provide data to understand better one of the main sources of PM₁₀ emissions in Bogota, such as road dust. These data will be useful to optimize environmental policies, and they may be used in future studies of human health and air quality modeling.

Using multi-site data to apportion PM-bound metal(loid)s: Impact of a manganese alloy plant in an urban area

The identification and quantification of the PM emission sources influencing a specific area is vital to better assess the potential health effects related to the PM exposure of the local population. In this work, a multi-site PM₁₀ sampling campaign was performed in seven sites located in the southern part of the Santander Bay (northern Spain), an urban area characterized by the proximity of some metal(loid) industrial sources (mainly a manganese alloy plant). The total content of V, Mn, Fe, Ni, Cu, Zn, As, Mo, Cd, Sb and Pb was determined by ICP-MS. This multi-site dataset was evaluated by positive matrix factorization (PMF) in order to identify the main anthropogenic metal(loid) sources impacting the studied area, and to quantify their contribution to the measured metal(loid) levels. The attribution of the sources was done by comparing the factor profiles obtained by the PMF analysis with representative profiles from known metal(loid) sources in the area, included in both the European database SPECIEUROPE (V2.0) and the US database EPA-SPECIATE (V4.5) or calculated from literature data. In addition, conditional bivariate probability functions (CBPF)s were used to assist in the identification of the sources. Four metal(loid) sources were identified: Fugitive and point source emissions from the manganese alloy plant (49.9% and 9.9%, respectively), non-exhaust traffic emissions (38.3%) and a minor source of mixed origin (1.8%). The PMF analysis was able to make a clear separation between two different sources from the manganese alloy plant, which represented almost 60% of the total measured metal(loid) levels, >80% of these emissions being assigned to fugitive emissions. These results will be useful for the assessment of the health risk associated with PM₁₀-bound metal(loid) exposure and for the design of efficient abatement strategies in areas impacted by similar industries.