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.

GAPS-megacities: A new global platform for investigating persistent organic pollutants and chemicals of emerging concern in urban air.

A pilot study was initiated in 2018 under the Global Atmospheric Passive Sampling (GAPS) Network named GAPS-Megacities. This study included 20 megacities/major cities across the globe with the goal of better understanding and comparing ambient air levels of persistent organic pollutants and other chemicals of emerging concern, to which humans residing in large cities are exposed. The first results from the initial period of sampling are reported for 19 cities for several classes of flame retardants (FRs) including organophosphate esters (OPEs), polybrominated diphenyl ethers (PBDEs), and halogenated flame retardants (HFRs) including new flame retardants (NFRs), tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCDD). The two cities, New York (USA) and London (UK) stood out with ∼3.5 to 30 times higher total FR concentrations as compared to other major cities, with total concentrations of OPEs of 15,100 and 14,100 pg/m3, respectively. Atmospheric concentrations of OPEs significantly dominated the FR profile at all sites, with total concentrations in air that were 2-5 orders of magnitude higher compared to other targeted chemical classes. A moderately strong and significant correlation (r = 0.625, p < 0.001) was observed for Gross Domestic Product index of the cities with total OPEs levels. Although large differences in FR levels were observed between some cities, when averaged across the five United Nations regions, the FR classes were more evenly distributed and varied by less than a factor of five. Results for Toronto, which is a 'reference city' for this study, agreed well with a more in-depth investigation of the level of FRs over different seasons and across eight sites representing different urban source sectors (e.g. traffic, industrial, residential and background). Future sampling periods under this project will investigate trace metals and other contaminant classes, linkages to toxicology, non-targeted analysis, and eventually temporal trends. The study provides a unique urban platform for evaluating global exposome.

Air quality variations in Northern South America during the COVID-19 lockdown.

Lockdown measures led to air pollution decrease in several countries around the world such as China and India, whereas other regions experimented an increase in pollutant concentrations. Northern South America (NSA) was one of those areas where pollution changed during lockdown due to high fire activity. This study aims to analyze, for the first time in NSA, the behavior of selected criteria air pollutants during the implementation of the SARS-CoV-2 lockdown in two high populated cities of the region: Bogotá and Medellín in Colombia. A set of tools including surface measurements, as well as satellite and modeled data were used. 24-hour average concentrations of PM10, PM2.5, and NO2 were collected from air quality stations for the lockdown period ranging from February 21 to June 30, 2020. The Copernicus Atmosphere Monitoring Service (CAMS) was used to analyze the fire flux OC as a biomass burning (BB) indicator, and tropospheric NO2 concentrations were retrieved from TROPOMI. The HYSPLIT model was used to analyze back trajectories and fire data were obtained from MODIS sensor measurements. Our analysis shows short-term background NO2, PM10, and PM2.5 concentration reductions of 60%, 44%, and 40%, respectively, for the strict lockdown; and 62%, 58%, and 69% for the relaxed lockdown. Corresponding long-term reductions were of 50%, 32%, and 9% for the strict lockdown; and 37%, 29%, and 19% for the relaxed lockdown. Regional BB increased PM2.5 concentrations by 20 µg/m3 during the strict lockdown, and the Saharan dust event increased PM10 concentrations up to 168 µg/m3 in Bogotá, and 104 µg/m3 in Medellín, bringing an additional risk of morbidity and mortality for population. Regional BB has several causes that need to be properly managed to benefit local air quality improvement plans. Future cleaner transport policies equivalent to reduced lockdown mobility could bring pollution close to WHO guidelines.

Air pollution emission effects of changes in transport supply: the case of Bogotá, Colombia.

Transportation policy and planning decisions, including decisions on new infrastructure and public transport improvements, affect local and global environmental conditions. This work studies the effect of increased road capacity on traffic-related emissions in Bogotá using a tool that couples a transportation model with emission factors from COPERT IV. We followed a parametric approach varying transport supply and demand, comparing three scenarios: a baseline scenario that represents the transportation system in Bogota in 2015; scenario 1 incorporates five highway capacity-enhancement projects in Bogotá and assumes insensitive travel demand; scenario 2 incorporates the new highway projects but assumes a demand increase of 13% in vehicle trips with private cars. Results include daily and annual values of traffic-related emissions of five air pollutant criteria: CO, NOx, PM10, SO2, and VOC for the baseline scenario, scenario 1, and scenario 2. We found a reduction in emissions after adding highway capacity and assuming inelastic demand (scenario 1). Scenario 1 results in a 15% reduction in PM10 emissions and a 10% reduction in NOx emissions. In contrast, results for scenario 2 suggest increased emissions for all air pollutant criteria (e.g., VOC and CO emissions increase by 21% and 22% compared with the baseline scenario). Therefore, new traffic demand would eliminate the emission savings observed in scenario 1 and could potentially further degrade air quality in Bogotá. While an exact estimate of induced demand that may result from highway expansion in Bogotá is not available, this analysis highlights that such projects could lead to an increase in emissions unless there is a combined effort to managing demand of private vehicle trips.

Development of a high-resolution traffic emission model: Lessons and key insights from the case of Bogotá, Colombia.

This paper presents a traffic-related air emissions inventory of a developing megacity using a traffic assignment model that results in a detailed temporal and spatial emission representation, disaggregating emissions sources by vehicle type and hour of the day, for five criteria air pollutants.

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

Bogota registers frequent episodes of poor air quality from high PM10 concentrations. It is one of the main Latin American megacities, located at 2600 m in the tropical Andes, but there is insufficient data on PM10 source contribution. A characterization of the chemical composition and the source apportionment of PM10 at an urban background site in Bogota was carried out in this study. Daily samples were collected from June 2015 to May 2016 (a total of 311 samples). Organic carbon (OC), elemental carbon (EC), water soluble compounds (SO42-, Cl-, NO3-, NH4+), major elements (Al, Fe, Mg, Ca, Na, K, P) and trace metals (V, Cd, Pb, Sr, Ba, among others) were analyzed. The results were interpreted in terms of their variability during the rainy season (RS) and the dry season (DS). The data obtained revealed that the carbonaceous fraction (∼51%) and mineral dust (23%) were the main PM10 components, followed by others (15%), Secondary Inorganic Compounds (SIC) (11%) and sea salt (0.4%). The average concentrations of soil, SIC and OC were higher during RS than DS. However, peak values were observed during the DS due to photochemical activity and forest fires. Although trace metals represented <1% of PM10, high concentrations of toxic elements such as Pb and Sb on RS, and Cu on DS, were obtained. By using a PMF model, six factors were identified (∼96% PM10) including fugitive dust, road dust, metal processing, secondary PM, vehicles exhaust and industrial emissions. Traffic (exhaust emissions + road dust) was the major PM10 source, accounting for ∼50% of the PM10. The results provided novel data about PM10 chemical composition, its sources and its seasonal variability during the year, which can help the local government to define control strategies for the main emission sources during the most critical periods.

Cuantificación de hidrocarburos policíclicos aromáticos urinarios en policías de tránsito del área metropolitana de Bogotá / Quantifying polycyclic aromatichydrocarbons in urine samples taken from traffic police working in Bogota's metropolitan area

Objetivos Cuantificar niveles urinarios de 1-hidroxipireno (1-OHP) y 3-hidroxibenzo [a] pireno (3-BAP) metabolitos de hidrocarburos policíclicos aromáticos (HAP) de interés toxicológico y relacionar su detección con el grado de exposición a material particulado de tamaño menor a 10 micras (PM10) u otros factores, en una población de Policías de Tránsito ocupacionalmente expuestos en el área metropolitana de Bogotá D.C. Métodos Se realizó un estudio de corte transversal en 524 Policías de Tránsito de los cuales 413 desarrollaban funciones operativas y 111 administrativas. Se tomaron muestras de orina de todos los individuos incluidos, para la determinación de metabolitos de HAP mediante cromatografía de gases con detección de masas. Se analizó la presencia de factores asociados con la detección de los metabolitos como tabaquismo, consumo de alimentos asados, lugar de residencia y exposición a PM10. Como medida de asociación se calcularon Odds Ratio (OR). Resultados Se encontraron niveles de 1-OHP y 3-BAP superiores en los individuos expuestos con OR significativos para detección de los metabolitos de 6,3 (IC 95% (3,6-11,1)) y 15,6 (IC 95% (6,2-39)), respectivamente. Se hallaron OR significativos para detección de metabolitos de HAP y exposición a PM10, tabaquismo y consumo de alimentos asados. Discusión Existe una asociación importante y significativa entre la exposición laboral a contaminación ambiental y la detección de metabolitos de HAP de importancia toxicológica en muestras de orina. Factores tales como tabaquismo, consumo de alimentos asados recientemente y exposición a PM10 también se encontraron asociados positivamente con la detección de dichos metabolitos pero en menor proporción.(AU)

Objective Quantifying polycyclic aromatic hydrocarbon levels in urine samples taken from a population of traffic police working in the metropolitan area of Bogotá who were occupationally exposed to 1-hydroxypyrene (1-OHP) and 3-hydroxy-benzo [a] pyrene (3-BaP) metabolites from polycyclic aromatic hydrocarbons (PAH) having toxicological interest, related to their detection, and a degree of exposure to particulate material having a size less than 10 micrometres (PM10) and/or other factors. Methods A cross-sectional study was made of 524 traffic police, 413 of whom were engaged in operational and 111 in administrative functions. Urine samples were taken from all the individuals included in the study for determining PAH metabolites by gas chromatography/mass spectrometry (GC/MS). The presence of factors associated with the detection of metabolites was analysed, such as smoking, consuming roasted/grilled food, place of residence and exposure to PM10. The odds ratio (OR) was calculated as a measure of association. Results Higher 1-OHP and 3-BaP levels were found in exposed individuals, having a significant OR for detecting 6.3 ((3.6-11.1) 95 % CI) and 15.6 ((6.2-39) 95 % CI) metabolites, respectively. Significant OR were found for detecting PAH metabolites and exposure to PM10, smoking and consuming roasted/grilled food. Discussion There was an important and significant association between work-related exposure to environmental contamination and detecting toxicologically important PAH metabolites in urine samples. Factors such as smoking, consuming freshly grilled/roasted food and exposure to PM10 were also found to be positively associated with detecting such metabolites, but to a lesser extent.(AU)

[Quantifying polycyclic aromatic hydrocarbons in urine samples taken from traffic police working in Bogota's metropolitan area]. / Cuantificación de hidrocarburos policíclicos aromáticos urinarios en policías de tránsito del área metropolitana de Bogotá

OBJECTIVE: Quantifying polycyclic aromatic hydrocarbon levels in urine samples taken from a population of traffic police working in the metropolitan area of Bogotá who were occupationally exposed to 1-hydroxypyrene (1-OHP) and 3-hydroxy-benzo[a]pyrene (3-BaP) metabolites from polycyclic aromatic hydrocarbons (PAH) having toxicological interest, related to their detection, and a degree of exposure to particulate material having a size less than 10 micrometres (PM10) and/or other factors. METHODS: A cross-sectional study was made of 524 traffic police, 413 of whom were engaged in operational and 111 in administrative functions. Urine samples were taken from all the individuals included in the study for determining PAH metabolites by gas chromatography/mass spectrometry (GC/MS). The presence of factors associated with the detection of metabolites was analysed, such as smoking, consuming roasted/grilled food, place of residence and exposure to PM10. The odds ratio (OR) was calculated as a measure of association. RESULTS: Higher 1-OHP and 3-BaP levels were found in exposed individuals, having a significant OR for detecting 6.3 ((3.6-11.1) 95 % CI) and 15.6 ((6.2-39) 95 % CI) metabolites, respectively. Significant OR were found for detecting PAH metabolites and exposure to PM10, smoking and consuming roasted/grilled food. DISCUSSION: There was an important and significant association between work-related exposure to environmental contamination and detecting toxicologically important PAH metabolites in urine samples. Factors such as smoking, consuming freshly grilled/roasted food and exposure to PM10 were also found to be positively associated with detecting such metabolites, but to a lesser extent.