Well-to-wheel emissions and abatement strategies for passenger vehicles in two Latin American cities.

More stringent standards for engines and fuels are progressively implemented as alternatives to reduce on-road vehicle emissions. While electric vehicles appear as a perfect alternative since their engines do not emit pollutants, wear and dust resuspension (W&R) and indirect emissions associated with electricity production remain significant sources of pollution. This work compares well-to-wheel emissions (WTW) and abatement strategies for various types of passenger vehicles in Bogotá and Santiago for different pollutants (CO, PM2.5, SO2, and NOx) and greenhouse gases like CO2 equivalent (CO2-Eq). Results show that WTW baseline emissions are more extensive in Bogotá than in Santiago (i.e., 58 and 30% for PM2.5 and CO2-Eq), mainly due to the higher vehicle activity and older state of Bogotá's fleet. We also evaluated extreme scenarios to assess the potential of a given vehicle technology or energy source to reduce emissions. We assessed, in particular, the replacement of all current vehicles by (1) conventional technologies with stricter emission standards and (2) battery electric vehicles powered with different energy resources. Our results indicate that replacing the current fleet with modern combustion technologies has a lower reduction potential than battery electric vehicles, but these reductions largely depend on the energy mix. Substitution by electric vehicles powered with electricity from renewable energies is the most efficient scenario in both cities. Finally, results also stress the importance of the resuspension of deposited road dust and brake and tire wear emissions in both cities as a crucial source of PM2.5, which must be better controlled.

Air pollution and COVID-19 lockdown in a large South American city: Santiago Metropolitan Area, Chile.

The implementation of confinement and physical distancing measures to restrict people's activities and transit in the midst of the COVID-19 pandemic allowed us to study how these measures affect the air quality in urban areas with high pollution rates, such as Santiago, Chile. A comparative study between the concentrations of PM10, PM2.5, NOx, CO, and O3 during the months of March to May 2020 and the corresponding concentrations during the same period in 2017-2019 is presented. A combination of surface measurements from the air quality monitoring network of the city, remote satellite measurements, and simulations of traffic activity and road transport emissions allowed us to quantify the change in the average concentrations of each pollutant. Average relative changes of traffic emissions (between 61% and 68%) implied statistically significant concentrations reductions of 54%, 13%, and 11% for NOx, CO, and PM2.5, respectively, during the pandemic period compared to historical period. In contrast, the average concentration of O3 increased by 63% during 2020 compared to 2017-2019. The nonlinear response observed in the pollution levels can be attributed to the changes in the vehicular emission patterns during the pandemic and to the role of other sources such as residential emissions or secondary PM.

Extirpación quirúrgica con cierre primario y uso de Isotretinoína en acné queloídeo de la nuca: serie de 6 casos clínicos / Acne keloidalis nuchae

El Acné queloídeo de la nuca se presenta principalmente en hombres jóvenes de raza negra; su etiología es desconocida, pero se piensa que sería multifactorial. El cuadro clínico corresponde a pápulas y pústulas que tienden a confluir en placas de aspecto queloídeo y que se observan como alopecia cicatricial, produciendo gran repercusión tanto física como psicológica en el paciente. Histológicamente se distingue una etapa temprana y una avanzada. No existe tratamiento curativo para este cuadro, pero se ha experimentado con múltiples opciones de tratamiento. En este trabajo se exponen los resultados de nuestra experiencia terapéutica con cirugía excisional asociada a cierre primario y posterior uso de Isotretinoína oral.

The Acne keloidalis nuchae occurs mainly in young black men; its etiology is unknown but is thought to be multifactorial. Clinically it presents as papules and pustules which tend to coalesce in keloid-like plaques and they are observed as scarring alopecia, producing great impact both physically and psychologically in the patient. An early and an advanced stage can be distinguished with histological techniques. There is no cure for this pathology, even though multiple treatments have been tried. In this paper, we expose the results of our therapeutic experience with excisional surgery associated with primary closure and subsequent use of oral Isotretinoin.

Miasis foruncular por Dermatobia Hominis: un diagnóstico emergente en Chile / Foruncular myiasis due to Dermatobia Hominis: a diagnosis emerging in Chile

Las lesiones cutáneas son causa frecuente de consulta en viajeros siendo las picaduras de insectos unas de las más prevalentes. Damos a conocer un caso de paciente que presenta una lesión dolorosa en cuero cabelludo, tras viaje a la selva boliviana, refractario a tratamiento antibiótico empírico y con estudio complementario inconcluyente. Finalmente, se realizó estudio macroscópico de la costra, que determinó que se trataba de una larva de Dermatobia Hominis. Este caso demuestra la importancia de tomar en cuenta estos agentes no presentes en Chile y que son causantes de patologías dermatológicas del viajero.

Cutaneous lesions are frequent cause of consultation in travelers, being insect bites one of the most prevalent. We present a case of a patient with a painful lesion on the scalp, after a trip to the Bolivian jungle, refractory to empirical antibiotic treatment and with an inconclusive complementary study. Finally, macroscopic study of the crust was carried out, which determined that it was a larva of Dermatobia Hominis. This case demonstrates the importance of taking into account these agents not present in Chile and that are the cause of dermatological pathologies of the traveler.

[Primary cutaneous anaplastic large cell lymphoma: Report of one case]. / Linfoma anaplástico de células grandes CD30 positivo cutáneo primario: reporte de un caso.

Primary cutaneous anaplastic large cell lymphoma (PCALCL) is within the spectrum of cutaneous CD30-positive lymphoproliferative disorders. It presents as localized or multifocal tumors or plaques and carries an excellent long-term prognosis even in cases with regional and/or ipsilateral lymph node involvement or in cases of recurrent disease. We report a 34 year-old female with a thigh lesion. Skin biopsy confirmed the diagnosis of PCALCL. The patient was strictly monitored but no treatment was instituted and the tumor regressed spontaneously. After 24 months of follow-up the patient remains free of disease without new lesions.

Linfoma anaplástico de células grandes CD30 positivo cutáneo primario: reporte de un caso / Primary cutaneous anaplastic large cell lymphoma: Report of one case

Primary cutaneous anaplastic large cell lymphoma (PCALCL) is within the spectrum of cutaneous CD30-positive lymphoproliferative disorders. It presents as localized or multifocal tumors or plaques and carries an excellent long-term prognosis even in cases with regional and/or ipsilateral lymph node involvement or in cases of recurrent disease. We report a 34 year-old female with a thigh lesion. Skin biopsy confirmed the diagnosis of PCALCL. The patient was strictly monitored but no treatment was instituted and the tumor regressed spontaneously. After 24 months of follow-up the patient remains free of disease without new lesions.

Cellular neurothekeoma: case report and its (un) relation with nerve sheath myxoma.

Neurothekeoma is an uncommon, benign neoplasm presenting in young adults, primarily on the head and neck. It was initially related to nerve sheath myxoma but with the advent of immunohistochemistry, new insights into its cellular differentiation and origin have emerged, unlinking Neurothekeoma and nerve sheath myxoma. Herein we describe a 19-year-old male who had had a frontal, flesh-colored, asymptomatic papule for 2 years. Histology showed a dermal fusocellular-spindle cell tumor, including an eosinophilic cytoplasm with mild cellular pleomorphism and moderately dense fibrous stroma. IHQ was positive for CD10 and negative for S100 and Claudin-1. These findings were compatible with cellular Neurothekeoma. The lesion was completely extirpated and at the 6-month follow-up, the patient was asymptomatic and had experienced no recurrences.

Cellular neurothekeoma: case report and its (un) relation with nerve sheath myxoma

Neurothekeoma is an uncommon, benign neoplasm presenting in young adults, primarily on the head and neck. It was initially related to nerve sheath myxoma but with the advent of immunohistochemistry, new insights into its cellular differentiation and origin have emerged, unlinking Neurothekeoma and nerve sheath myxoma. Herein we describe a 19-year-old male who had had a frontal, fl esh-colored, asymptomatic papule for 2 years. Histology showed a dermal fusocellular-spindle cell tumor, including an eosinophilic cytoplasm with mild cellular pleomorphism and moderately dense fi brous stroma. IHQ was positive for CD10 and negative for S100 and Claudin-1. These fi ndings were compatible with cellular Neurothekeoma. The lesion was completely extirpated and at the 6-month follow-up, the patient was asymptomatic and had experienced no recurrences.

Eritema flagelado / Flagellate erythema

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Estimating the health benefits from natural gas use in transport and heating in Santiago, Chile.

Chilean law requires the assessment of air pollution control strategies for their costs and benefits. Here we employ an online weather and chemical transport model, WRF-Chem, and a gridded population density map, LANDSCAN, to estimate changes in fine particle pollution exposure, health benefits, and economic valuation for two emission reduction strategies based on increasing the use of compressed natural gas (CNG) in Santiago, Chile. The first scenario, switching to a CNG public transportation system, would reduce urban PM2.5 emissions by 229 t/year. The second scenario would reduce wood burning emissions by 671 t/year, with unique hourly emission reductions distributed from daily heating demand. The CNG bus scenario reduces annual PM2.5 by 0.33 µg/m³ and up to 2 µg/m³ during winter months, while the residential heating scenario reduces annual PM2.5 by 2.07 µg/m³, with peaks exceeding 8 µg/m³ during strong air pollution episodes in winter months. These ambient pollution reductions lead to 36 avoided premature mortalities for the CNG bus scenario, and 229 for the CNG heating scenario. Both policies are shown to be cost-effective ways of reducing air pollution, as they target high-emitting area pollution sources and reduce concentrations over densely populated urban areas as well as less dense areas outside the city limits. Unlike the concentration rollback methods commonly used in public policy analyses, which assume homogeneous reductions across a whole city (including homogeneous population densities), and without accounting for the seasonality of certain emissions, this approach accounts for both seasonality and diurnal emission profiles for both the transportation and residential heating sectors.

Comparison of vehicle activity and emission inventory between Beijing and Shanghai.

Vehicle emission inventory is a critical element for air quality study. This study created systemic methods to establish a vehicle emission inventory in Chinese cities. The methods were used to obtain credible results of vehicle activity in Beijing and Shanghai. On the basis of the vehicle activity data, the International Vehicle Emission model is used to establish vehicle emission inventories. The emissions analysis indicates that 3 t of particulate matter (PM), 199 t of nitrogen oxides (NO(x)), 192 t of volatile organic compounds (VOCs), and 2403 t of carbon monoxide (CO) are emitted from on-road vehicles each day in Beijing, whereas 4 t of PM, 189 t of NO(x), 113 t of VOCs, and 1009 t of CO are emitted in Shanghai. Although common features were found in these two cities (many new passenger cars and a high taxi proportion in the fleet), the emission results are dissimilar because of the different local policy regarding vehicles. The method to quantify vehicle emission on an urban scale can be applied to other Chinese cities. Also, knowing how different policies can lead to diverse emissions is beneficial knowledge for other city governments.

Hot emission model for mobile sources: application to the metropolitan region of the city of Santiago, Chile.

Depending on the final application, several methodologies for traffic emission estimation have been developed. Emission estimation based on total miles traveled or other average factors is a sufficient approach only for extended areas such as national or worldwide areas. For road emission control and strategies design, microscale analysis based on real-world emission estimations is often required. This involves actual driving behavior and emission factors of the local vehicle fleet under study. This paper reports on a microscale model for hot road emissions and its application to the metropolitan region of the city of Santiago, Chile. The methodology considers the street-by-street hot emission estimation with its temporal and spatial distribution. The input data come from experimental emission factors based on local driving patterns and traffic surveys of traffic flows for different vehicle categories. The methodology developed is able to estimate hourly hot road CO, total unburned hydrocarbons (THCs), particulate matter (PM), and NO(x) emissions for predefined day types and vehicle categories.