Aglomeración urbana en la estimación de escenarios de riesgo sanitario por emisiones de gasolineras: el caso de Ensenada, Baja California / Urban crowding in the estimation of health risk scenarios caused by emissions from gas stations: the case of Ensenada, Baja California / Aglomeração urbana na estimação de cenários de risco para a saúde por emissões em postos de gasolina: o caso da cidade de Ensenada, Baixa Califórnia

Resumen Objetivo: se propone una herramienta conceptual y metodológica mediante la cual es posible representar la contribución de los componentes sociales, económicos y territoriales en la aglomeración de personas dentro de una ciudad, para delimitar zonas de riesgo sanitario por la exposición a emisiones de gasolina en estaciones de servicio. Resultados: el modelo propuesto facilita la focalización, identificación y priorización las zonas de riesgo por contaminación ambiental por BTEX liberados por gasolineras. Discusión: la inclusión en modelos espaciales de riesgo, del número de personas que acuden a construcciones como escuelas y hospitales que generan aglomeración, trasciende el ámbito conceptual y ofrece aspectos metodológicos e instrumentales para lograr modelos más robustos y aplicables en otras ciudades. Las agencias gubernamentales deben considerar estos resultados para el establecimiento de reglas, permisos y procedimientos de ejecución con el fin de reducir la contaminación del medio ambiente y, con esto, mejorar las condiciones sanitarias en el entorno complejo de una zona urbana. Conclusiones: el análisis espacial integrado no resuelve las complicadas negociaciones políticas y sociales que se tienen que hacer en la toma de decisiones sobre los riesgo sanitario, lo que sí mejora es la capacidad de los científicos y tomadores de decisiones en la identificación, evaluación, control y reducción de estos riesgos asociados con las emisiones de las estaciones de servicio.

Abstract Objective: a conceptual and methodological tool is proposed which makes it possible to represent how social, economic and territorial components contribute to the crowding of people within a city. This tool aims to define the areas with health risk due to exposure to gasoline emissions from gas stations. Results: the proposed model can facilitate the targeting, identification and prioritization of zones at risk of environmental contamination by the BTEX released from gas stations in the city. Discussion: when a spatial model of risk includes the number of people going to buildings that generate crowding such as schools and hospitals, the conceptual scope is transcended and methodological and instrumental aspects are offered in order to achieve more robust models that are applicable to other cities. Government agencies should take these results into account when establishing rules, permits and enforcement procedures to reduce environmental contamination. This would thus improve the health conditions in the complex environment of an urban area. Conclusions: integrated spatial analysis does not solve the complicated social and political negotiations that must take place in any decision making concerning health risk. However, it does improve the ability of scientists and decision-makers to identify, assess, control and reduce the risks associated with emissions from gas stations.

Resumo Objetivo: Propõe-se uma ferramenta conceitual e metodológica por meio da qual é possível representar a contribuição dos componentes sociais, econômicos e territoriais na aglomeração de pessoas em uma cidade, para demarcar zonas de risco para a saúde por causa da exposição a emissões de gasolina em postos de abastecimento. Resultados: O modelo proposto facilita a focalização, identificação e priorização das zonas de risco por poluição ambiental por BTEX emitidos pelos postos de gasolina. Discussão: A inclusão em modelos espaciais de risco, do número de pessoas que frequentam estabelecimentos como escolas e hospitais que geram aglomeração, transcende o âmbito conceitual e oferece aspectos metodológicos e instrumentais para conseguir modelos mais robustos e aplicáveis em outras cidades. As agências governamentais precisam considerar estes resultados para a criação de regras, autorizações e procedimentos de execução com o propósito de reduzir a poluição do meio-ambiente e, assim, melhorar as condições de saúde no entorno complexo de uma zona urbana. Conclusões: A análise espacial integrada não resolve as complicadas negociações políticas e sociais que devem acontecer na tomada de decisões sobre os riscos de saúde, mas o que melhora é a capacidade dos cientistas tomadores de decisões na identificação, avaliação, controle e redução destes riscos associados com as emissões dos postos de abastecimento.

Low-wind/high particulate matter episodes in the Calexico/Mexicali region.

The U.S. Environmental Protection Agency (EPA) currently classifies Imperial County, CA, as a nonattainment area for PM10 (particulate matter [PM] < or = 10 microm in diameter), and this region suffers from high rates of chronic bronchitis and childhood asthma. Although high annual and daily average PM levels can have negative health and economic effects, recent studies have identified an association between adverse health effects and short-term PM spikes of tens of micrograms per cubic meter. This study identified PM episodes in Calexico/Mexicali that involve PM concentration spikes with concentrations up to 10 times greater than those reported to cause adverse health effects. These episodes appear to be relatively common during the winter months, are associated with wind speeds below 2 m/sec and stable boundary level heights below 500 m, and can comprise a large portion of the 24-hr PM levels. The organic composition of the PM10 samples collected during the low-wind/ high-PM episodes differed from that collected at other times. However, a preliminary source attribution identified only one significant difference between the source classes: agricultural burning accounted for 6.7% of organic-fraction PM10 for low-wind/high-PM episodes versus 0.25% at other times. This preliminary source attribution also revealed that motor vehicles were the most important relative contributor to organic PM10.

Black carbon and polycyclic aromatic hydrocarbon emissions from vehicles in the United States-Mexico border region: pilot study.

The investigators developed a system to measure black carbon (BC) and particle-bound polycyclic aromatic hydrocarbon (PAH) emission factors during roadside sampling in four cities along the United States-Mexico border, Calexico/Mexicali and El Paso/Juarez. The measurement system included a photoacoustic analyzer for BC, a photoelectric aerosol sensor for particle-bound PAHs, and a carbon dioxide (CO2) analyzer. When a vehicle with measurable emissions passed the system probe, corresponding BC, PAH, and CO2 peaks were evident, and a fuel-based emission factor was estimated. A picture of each vehicle was also recorded with a digital camera. The advantage of this system, compared with other roadside methods, is the direct measurement of particulate matter components and limited interference from roadside dust. The study revealed some interesting trends: Mexican buses and all medium-duty trucks were more frequently identified as high emitters of BC and PAH than heavy-duty trucks or passenger vehicles. In addition, because of the high daily mileage of buses, they are good candidates for additional study. Mexican trucks and buses had higher average emission factors compared with U.S. trucks and buses, but the differences were not statistically significant. Few passenger vehicles had measurable BC and PAH emissions, although the highest emission factor came from an older model passenger vehicle licensed in Baja California.