Gerardo Mejia - Academia.edu (original) (raw)
Papers by Gerardo Mejia
Environmental Sustainability Issues in the South Texas–Mexico Border Region, 2013
ABSTRACT The United States (U.S.) – Mexico border region have experienced high economic and popul... more ABSTRACT The United States (U.S.) – Mexico border region have experienced high economic and population growth which have led to environmental consequences, such as air pollution, that affect human health. The objective of this study was to assess the impacts of air quality on public health for the South Texas – Northeastern Mexico border region by means of environmental health indicators that correlate air quality data with epidemiological data for respiratory and cardiovascular illness, and facilitates interpretation of outcomes and trends. The study established that particulate matter (PM), both PM10 and PM2.5, have a significant effect on heart disease, stroke, and asthma in South Texas. The data show that asthma is prevalent along the border region, and for the Mexican State of Tamaulipas, the study demonstrated a higher correlation between PM10 and asthma than any other disease. The study also shows a statistically strong correlation between ambient ozone (O3) concentrations and mortality due to heart disease. Although some correlation appears to exist between other air pollutants such as carbon monoxide (CO), O3 and PM2.5 with mortality rates due to stroke, chronic lower respiratory disease (CLRD), and with morbidity rate due to asthma, the statistical significance of these correlations were not supported by the t-test results.
Environmental Sustainability Issues in the South Texas–Mexico Border Region, 2013
ABSTRACT The prevalence of asthma, allergic rhinitis, and eczema in school children in the cities... more ABSTRACT The prevalence of asthma, allergic rhinitis, and eczema in school children in the cities of Northeastern Mexican State of Tamaulipas and potential correlation with ambient pollution factors were studied using the International Study of Asthma and Allergies in Childhood (ISAAC) epidemiology research methodology Phase 1. The study indicates that asthma and rhinitis are more prevalent than eczema in both elementary and middle school children with rhinitis prevalence significantly higher in Reynosa elementary school children. Asthma was more prevalent in Nuevo Laredo middle school children than in the other cities’ middle school children likely due to higher frequency of smoking among children as a very strong correlation was found between asthma occurrence and children smoking habits. Lead and pesticide intoxications are higher in middle school children than in elementary school children. Middle school children in Nuevo Laredo exhibit two or more time the pesticide intoxications than middle school children in Reynosa and Matamoros; however, the study indicates that Matamoros has the highest outdoor fumigation and Nuevo Laredo the lowest indoor fumigation. Indoor air quality may also be a factor as the study shows the combined results for the three cities of Matamoros, Reynosa, and Nuevo Laredo that 60 % of households use coal or wood for heating purposes, and 60 % of households use natural gas for cooking.
Environment International, 1997
This study characterized and estimated emissions of air pollutants from fuel burning on the Mexic... more This study characterized and estimated emissions of air pollutants from fuel burning on the Mexican side of the Lower Rio Grande border region, from Matamoros to Reynosa, Mexico. In the methodology of this study, emissions were estimated using emission factors ...
Rising global temperatures and seawater temperatures have led to an increase in extreme weather p... more Rising global temperatures and seawater temperatures have led to an increase in extreme weather patterns leading to droughts and floods. These natural phenomena, in turn, affect the supply of drinking water in some communities, which causes an increase in the prevalence of diseases related to the supply of drinking water. The objective of this work is to demonstrate the effects of global warming on human health in the population of Monterrey, Mexico after Hurricane Alex. We interpolated data using statistical downscaling of climate projection data for 2050 and 2080 and correlated it with disease occurrence. We found a remarkable rise in the incidence of transmissible infectious disease symptoms. Gastrointestinal symptoms predominated and were associated with drinking of contaminated water like tap water or water from communal mobile water tanks, probably because of the contamination of clean water, the disruption of water sanitation, and the inability to maintain home hygiene practi...
Salud Pública de México, 2014
Objetivo. Establecer las concentraciones de plomo (Pb) en sangre en niños escolares de 1998 y 200... more Objetivo. Establecer las concentraciones de plomo (Pb) en sangre en niños escolares de 1998 y 2008, así como su asociación con factores de riesgo. Material y métodos. Se llevó a cabo un monitoreo de Pb en sangre de niños de entre 6 y 12 años que cursan educación primaria en 17 escuelas diferentes, ubicadas en distintas zonas del área metropolitana de Monterrey, de 1998 a 2008. Resultados. Se obtuvieron niveles séricos de 9.6 ± 3.0 (μg/dL rango de 3.18 a 20.88) en 1998 y de 4.5±4.8 μg/dL (rango de 3.3 a 53.7) en 2008, lo que mostró una disminución de 2.1 veces en nivel de Pb (p menor que 0.01). Conclusiones. La reducción de los niveles séricos de Pb demuestran los mejores controles ambientales e industriales y probablemente el éxito de retirar el Pb de la gasolina durante los años noventa.
The Monterrey Metropolitan Area (MMA) is the third largest urban area in Mexico. Its population i... more The Monterrey Metropolitan Area (MMA) is the third largest urban area in Mexico. Its population is around 4 million and the vehicle fleet around 1.6 million, being the metropolitan zone with more vehicles per capita in Mexico. Industry, commerce and population are increasing fast in the MMA. Traffic activities are saturating the city and the introduction of used vehicles from the U.S. will increase the fleet and may have an important contribution in emissions. The emission inventory of the MMA has not been actualized since 1995 and only an aggregated emission inventory by municipality was published in 1999. In this work we present and discuss the results of the 2005 mobile source emission inventory. The MMA vehicle fleet was classified in accordance with the Mobile6.2 Mexico model. This is the most recent model developed for use in Mexico to estimate mobile source emissions. The results of the study show that about 14% of vehicles are from 1981 and before, 51% are in the range 1982-1999, and only 35 % are models 2000 to 2006. The 2006 models considered were sold at the end of 2005. We calculated emissions of CO, NO, SO 2, VOCs, PM 10 , PM 2.5 , NH 3 and CO 2. The results show that more than 6.3 millions of tons of CO2 were emitted and 0.58 million tons of the other pollutants (84.5% of CO, 9.6% of VOCs, 5.45% of NO and the rest of the other pollutants). Private vehicles (sedans and SUVs) contribute with 63.9% of the emissions and public transportation vehicles (taxis and buses) with 20.9%. Important findings are that vehicles 1987 and before contribute with 60% of the CO emissions and with almost 70% VOCs emissions. We estimate that the introduction of 300 thousand used vehicles may have an impact on emissions in the order of 12.7%.
The Monterrey Metropolitan Area (MMA) is the third largest urban area in Mexico. Its population i... more The Monterrey Metropolitan Area (MMA) is the third largest urban area in Mexico. Its population is around 4 million and the vehicle fleet around 1.6 million, being the metropolitan zone with more vehicles per capita in Mexico. Industry, commerce and population are increasing fast in the MMA. Traffic activities are saturating the city and the introduction of used vehicles from the U.S. will increase the fleet and may have an important contribution in emissions. The emission inventory of the MMA has not been actualized since 1995 and only an aggregated emission inventory by municipality was published in 1999. In this work we present and discuss the results of the 2005 mobile source emission inventory. The MMA vehicle fleet was classified in accordance with the Mobile6.2 Mexico model. This is the most recent model developed for use in Mexico to estimate mobile source emissions. The results of the study show that about 14% of vehicles are from 1981 and before, 51% are in the range 1982-...
![Research paper thumbnail of [A decade of lead monitoring in schoolchildren in the metropolitan area of Monterrey NL, Mexico]](https://attachments.academia-assets.com/68676053/thumbnails/1.jpg)
](Salud pública de México
To establish the blood lead concentration and associated risk factors in schoolchildren during 19... more To establish the blood lead concentration and associated risk factors in schoolchildren during 1998 and 2008. A blood lead screening was conducted in schoolchildren of 6-12 years of age, enrolled in 17 elementary schools of the metropolitan area of Monterrey, México, during 1998 and 2008. The mean blood lead level were 9.6 ± 3.0 (µg/dL range of 3.18 to 20.88) in 1998 and 4.5±4.8 µg/dL (range of 3.3 to 53.7) showing a 2.1-times reduction in blood lead levels (p<0.01). This reduction in blood lead levels demonstrate environmental and industrial control improvements and the benefits of fading out the leaded gasoline during the 1990's.
Journal of Environmental Engineering, 2015
ABSTRACT Mobile-source emission inventories in countries such as Mexico still require empirical d... more ABSTRACT Mobile-source emission inventories in countries such as Mexico still require empirical data to complement modeling tools because these tools are based on few local observations. In this study, emission factors (EFs) were determined for 10 light-duty gasoline-powered vehicles as a function of cruising speed under real-world driving conditions typical of the Monterrey metropolitan area, the third largest urban center in Mexico. Greater variability in the EF was found when the vehicles were operated at lower speeds, specifically at 10 km/h ; however, above 40 km/h , the changes were marginal. Engine size was the factor that most influenced the emissions of CO 2 , which were significantly greater in vehicles with an engine size above 2 L. A reduction trend in the CO-to-NO x ratio of newer model vehicles was observed. Upon comparison of the experimental results with the results obtained from the MOBILE6.2-Mexico and the MOVES 2010a models, it was determined that the latter model better described the values of the EFs, the emission profile as a function of speed, and the CO-to-NO x ratio of the tailpipe gases. Read More: http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EE.1943-7870.0000935
Revista Panamericana de Salud Pública, 2009
Journal of the Air & Waste Management Association, 2012
The Monterrey Metropolitan Area (MMA) has shown a high concentration of PM2.5 in its atmosphere s... more The Monterrey Metropolitan Area (MMA) has shown a high concentration of PM2.5 in its atmosphere since 2003. The contribution of possible sources of primary PM2.5 and its precursors is not known. In this paper we present the results of analyzing the chemical composition of sixty 24-hr samples of PM2.5 to determine possible sources of PM2.5 in the MMA. The samples were collected at the northeast and southeast of the MMA between November 22 and December 12, 2007, using low-volume devices. Teflon and quartz filters were used to collect the samples. The concentrations of 16 airborne trace elements were determined using x-ray fluorescence (XRF). Anions and cations were determined using ion chromatography. Organic carbon (OC) and elemental carbon (EC) were determined by thermal optical analysis. The results show that Ca had the maximum mean concentration of all elements studied, followed by S. Enrichment factors above 50 were calculated for S, Cl, Cu, Zn, Br and Pb. This indicates that these elements may come from anthropogenic sources. Overall, the major average components of PM2.5 were OC (41.7%), SO4(2-) (22.9%), EC (7.4%), crustal material (11.4%), and NO3- (12.6%), which altogether accounted for 96% of the mass. Statistically, we did not find any difference in SO4(2-) concentrations between the two sites. The fraction of secondary organic carbon was between 24% and 34%. The results of the factor analysis performed over 10 metals and OC and EC show that there are three main sources of PM2.5: crustal material and vehicle exhaust; industrial activity; and fuel oil burning. The results show that SO4(2-), OC, and crustal material are important components of PM2.5 in MMA. Further work is necessary to evaluate the proportion of secondary inorganic and organic aerosol in order to have a better understanding of the sources and precursors of aerosols in the MMA.
Journal of Petroleum Science and Engineering, 1995
Accurate estimates of multiphase flow functions (relative permeability and capillary pressure) ar... more Accurate estimates of multiphase flow functions (relative permeability and capillary pressure) are necessary for reliable prediction of oil recovery from a reservoir and nonaqueous phase (NAPL) contaminants from aquifers. Current methods of estimating two-phase relative permeabilities from unsteady state displacement experiments are based on Buckley-Leverett model. This model assumes that the medium is homogeneous, flow is one-dimensional and capillary effects
Journal of Petroleum Science and Engineering, 2010
Reservoir relative permeability and capillary pressure, as a function of saturation, is important... more Reservoir relative permeability and capillary pressure, as a function of saturation, is important for assessing reservoir hydrocarbon recovery, selecting the well completion method, and determining the production strategy because they are fundamental inputs to reservoir simulation for predicting lifetime production of a well. Estimation of relative permeability and capillary pressure curves at reservoir conditions is also an important task for successful planning of waterflooding and enhanced oil recovery. The relative permeability and capillary pressure data estimated from core analysis might cause concern regarding representativeness, and adjustments are typically necessary for successful production forecasting. This paper proposes a new method to obtain relative permeability and capillary pressure curves with downhole pressure-transient analysis (PTA) of mini-drillstem tests (miniDSTs) and well log-derived saturations. The new approach was based on performing miniDSTs in the free water, oil, and oil-water transition zones. Analyses of the miniDST buildup tests provided absolute formation permeability, endpoints of relative permeability to both oil and water, and curvature of the relative permeability data. Additionally, resistivity, dielectric, and nuclear magnetic resonance (NMR) logs were used to determine irreducible water, residual oil, and transition zone saturations. Combining these downhole measurements provided the relative permeability and capillary pressure curves.
AGU Spring …, 2007
Results of VOCs speciation from industrial steam boiler stacks located in Naucalpan are presented... more Results of VOCs speciation from industrial steam boiler stacks located in Naucalpan are presented and discussed. This municipality is located north of the Metropolitan Zone of the Valley of Mexico (MZVM). Speciation of VOCs is important to generate information about sources of pollution, to update emission inventories, to study the dynamics of pollutants in the atmosphere, and to estimate possible
scerp.org
The Four-state Region (FSR), as defined by the binational Border 2012 Environmental Program, incl... more The Four-state Region (FSR), as defined by the binational Border 2012 Environmental Program, includes those portions of the Mexican states of Tamaulipas, Nuevo León, and Coahuila within 100 kilometers (km) of the international border and the counties of Texas that fall ...
In this essay, we address the broad issue of environmental security in the U.S.-Mexico border reg... more In this essay, we address the broad issue of environmental security in the U.S.-Mexico border region. The heart of the paper is an examination of the two aspects of environment that are most closely related to human health and well-being: the region's water resources and its air quality. In order to frame our discussion in a context that considers the area's security, we begin by offering our perspective on how to interpret that term so that it can be applied meaningfully to the region's environment. As the next section argues, our understanding of security is expansive, allowing us to speak directly to environmental concerns, thus leaving to others questions of militarization, immigration, drug trafficking, and enforcement. 1. Environment and security: A post-realist perspective Environment and security in the U.S.-Mexico border region-and in any transboundary regionare closely intertwined. Each may and usually does affect the other. Environmental processes in one country, such as droughts, floods, sewage flows, and air pollution, may become serious enough to harm the neighboring country. Conversely, one nation's security-protection actions such as militarization, drug interdiction, fencing, and patrolling for cross-border immigrants can adversely impact the other nation's environment and natural resources. This interrelationship is further complicated by a deeper distinction between hard "traditionalist" or "realist" views of national security on the one hand-and softer, alternative, "nontraditionalist" or "post-realist" interpretations on the other hand. Adherents of the realist, or neo-Hobbesian school of thought see security as a critical part of a nation's sovereignty and therefore as a fundamental, absolute right, with an obligation to preserve it at any cost. According to this interpretation, arising from age-old competition for territory and resources, the concept of "national security" is used to justify maintenance of armies, the development of new weapons systems, and the manufacture of armaments. Military strength-and in recent history, economic power, as well-is the trump card and the nation that possesses the greatest measure of it earns the right to protect itself and its interests absolutely. This perspective prevailed across the globe until the collapse of the Soviet Union and the ensuing end of the Cold War (Dalby, 1992; A. Dinar, 2000). Realists examining environment and security in the U.S.-Mexico case would undoubtedly be most interested in instances where conflicts threaten stability and well-being in one of the states. Salient illustrations include such events as Mexico's delay during the drought of the mid-2000s in meeting treaty obligations to supply critical water to the Rio Grande/Río Bravo; the United States' decision to line the All-American Canal, depriving Mexican farmers of crossborder seepage; and the border security wall's flood causation in Nogales, Sonora, in 2008. Realists would view such instances as serious assaults on their nation's security and would advocate forceful, unilateral measures to impose solutions. But by the late 1970s and early 1980s, although the Cold War still raged, a number of writers-Lester R. Brown was among the vanguard-challenged the realist view of international relations and began in effect "rethinking security" (Brown, 1997; Ullman, 1983; Dalby, 1992). In the early debates, the non-traditionalists argued for a radical expansion of the concept of security to include social, economic, demographic, agricultural, and natural-resources-related matters. Among those at the forefront of this movement to "securitize" environmental issues 1 (Liverman, 2009) were scholars writing about environmental change. Norman Myers and Jessica Mathews, both writing in 1989, were among the early proponents of this view. They saw clearly that because security is contingent on stability and peace, environmental problems and population growth were critical aspects of national security (Myers, 1989; Mathews, 1989) 2. Appreciating the nuances of the rapidly changing relationship between humanity and natural systems and resources, Brown, Myers, Mathews, and other non-traditionalists recognized tradeoffs between security and other values. One important result of this insight was a rise in the importance of environmental issues and the consequent attention to cooperative approaches to transboundary conflicts (A. Dinar, 2010, forthcoming). In this vein, Aaron Wolf, in a seminal 1998 essay (and in a decade of work since), effectively refuted the notion that international water conflicts will inescapably lead to water wars; he demonstrates that historically, cooperation on transboundary waterways disputes has been far and away the prevalent outcome for more than two millennia (Wolf, 1998; 2007; Campbell and Weitz, 2007a). These findings are relevant for the U.S.-Mexico border region. In the years since the initial redefinition of security, writers have continued broadening the term to encompass food security and poverty, climate variability and change, water security, and energy. This more holistic conception of security underlines environmental problems that threaten the health and wellbeing of individuals or economic security of countries (Falkenmark, 2000). The topic water and security has arisen as byproduct of the growing interest in environment and security. Expanding the definition security yet further, Karen O'Brien and Robin Leichenko (2000) proposed a linkage of globalization and climate change, terming the risk from those two combined forces, "double exposure." Through the work of the Global Environmental Change and Human Security [GECHS] project and other efforts, this initial pairing has grown to be multidimensional. This line of reasoning links multiple forces such as globalization, energy demand, poverty, disease, and conflict, which acting in concert, could severely impact communities, society, environment, and stability-in other words, by definition, national security. This more comprehensive line of thinking has been growing. 3 The environmental-human security dimensions are in fact the reason behind the establishment of the United Nations Institute for Environment and Human Security (UNU-EHS) in 2004, under the United Nations University umbrella. For UNU-EHS (2005, p. 3) safeguarding human security requires a new approach, and better knowledge of many interrelated variables-social, political, economic, technological and environmental-which determine the impact of extreme events
Paso del Norte Air …, 2005
Although far from comprehensive with regard to temporal and spatial coverage, the first geographi... more Although far from comprehensive with regard to temporal and spatial coverage, the first geographic information system (GIS)-referenced database on Paso del Norte air quality parameters and impacts is already facilitating development of a variety of advanced models, including diagnostic meteorological models and particulate matter (PM) source and receptor models. When used in conjunction with each other, these models shed light on some of the complex atmospheric transport, reaction, and deposition processes that have confounded past attempts at understanding and predicting Paso del Norte air quality problems in general and fluctuations in ambient PM composition and concentrations in particular.
The Mexico-United States border area has become an increasingly important region due to its comme... more The Mexico-United States border area has become an increasingly important region due to its commercial, industrial and urban growth. As a result, environmental concerns have risen. Treaties like the North American Free Trade Agrement (NAFTA) have further motivated the development of environmental impact assessment in the area. Of particular concern is air quality, and how the activities on both sides of the border contribute to its degradation. This paper presents results of applying a three-dimensional photochemical airshed model to study air pollution dynamics along the Mexico-United States border. In addition, studies were conducted to assess how size resolution impacts the model performance. The model performed within acceptable statistic limits using 12.5 x 12.5 km 2 grid cells, and the benefits using finer grids were limited. Results were further used to assess the influence of grid-cell size on the modeling of control strategies, where coarser grids lead to significant loss of information.
AIChE Journal, 1996
This volume contains 102 papers presented at the National Heat Transfer Symposium of Japan. They ... more This volume contains 102 papers presented at the National Heat Transfer Symposium of Japan. They are divided into numerous sections, the titles of which include: enhancement of convective heat transfer; radiation heat transfer; modelling and numerical analysis of two-phase flow; visualization and measurement of twophase flow; film boiling; heat exchangers; heat transfer in combustion; heat pumps and refrigeration.
Environmental Sustainability Issues in the South Texas–Mexico Border Region, 2013
ABSTRACT The United States (U.S.) – Mexico border region have experienced high economic and popul... more ABSTRACT The United States (U.S.) – Mexico border region have experienced high economic and population growth which have led to environmental consequences, such as air pollution, that affect human health. The objective of this study was to assess the impacts of air quality on public health for the South Texas – Northeastern Mexico border region by means of environmental health indicators that correlate air quality data with epidemiological data for respiratory and cardiovascular illness, and facilitates interpretation of outcomes and trends. The study established that particulate matter (PM), both PM10 and PM2.5, have a significant effect on heart disease, stroke, and asthma in South Texas. The data show that asthma is prevalent along the border region, and for the Mexican State of Tamaulipas, the study demonstrated a higher correlation between PM10 and asthma than any other disease. The study also shows a statistically strong correlation between ambient ozone (O3) concentrations and mortality due to heart disease. Although some correlation appears to exist between other air pollutants such as carbon monoxide (CO), O3 and PM2.5 with mortality rates due to stroke, chronic lower respiratory disease (CLRD), and with morbidity rate due to asthma, the statistical significance of these correlations were not supported by the t-test results.
Environmental Sustainability Issues in the South Texas–Mexico Border Region, 2013
ABSTRACT The prevalence of asthma, allergic rhinitis, and eczema in school children in the cities... more ABSTRACT The prevalence of asthma, allergic rhinitis, and eczema in school children in the cities of Northeastern Mexican State of Tamaulipas and potential correlation with ambient pollution factors were studied using the International Study of Asthma and Allergies in Childhood (ISAAC) epidemiology research methodology Phase 1. The study indicates that asthma and rhinitis are more prevalent than eczema in both elementary and middle school children with rhinitis prevalence significantly higher in Reynosa elementary school children. Asthma was more prevalent in Nuevo Laredo middle school children than in the other cities’ middle school children likely due to higher frequency of smoking among children as a very strong correlation was found between asthma occurrence and children smoking habits. Lead and pesticide intoxications are higher in middle school children than in elementary school children. Middle school children in Nuevo Laredo exhibit two or more time the pesticide intoxications than middle school children in Reynosa and Matamoros; however, the study indicates that Matamoros has the highest outdoor fumigation and Nuevo Laredo the lowest indoor fumigation. Indoor air quality may also be a factor as the study shows the combined results for the three cities of Matamoros, Reynosa, and Nuevo Laredo that 60 % of households use coal or wood for heating purposes, and 60 % of households use natural gas for cooking.
Environment International, 1997
This study characterized and estimated emissions of air pollutants from fuel burning on the Mexic... more This study characterized and estimated emissions of air pollutants from fuel burning on the Mexican side of the Lower Rio Grande border region, from Matamoros to Reynosa, Mexico. In the methodology of this study, emissions were estimated using emission factors ...
Rising global temperatures and seawater temperatures have led to an increase in extreme weather p... more Rising global temperatures and seawater temperatures have led to an increase in extreme weather patterns leading to droughts and floods. These natural phenomena, in turn, affect the supply of drinking water in some communities, which causes an increase in the prevalence of diseases related to the supply of drinking water. The objective of this work is to demonstrate the effects of global warming on human health in the population of Monterrey, Mexico after Hurricane Alex. We interpolated data using statistical downscaling of climate projection data for 2050 and 2080 and correlated it with disease occurrence. We found a remarkable rise in the incidence of transmissible infectious disease symptoms. Gastrointestinal symptoms predominated and were associated with drinking of contaminated water like tap water or water from communal mobile water tanks, probably because of the contamination of clean water, the disruption of water sanitation, and the inability to maintain home hygiene practi...
Salud Pública de México, 2014
Objetivo. Establecer las concentraciones de plomo (Pb) en sangre en niños escolares de 1998 y 200... more Objetivo. Establecer las concentraciones de plomo (Pb) en sangre en niños escolares de 1998 y 2008, así como su asociación con factores de riesgo. Material y métodos. Se llevó a cabo un monitoreo de Pb en sangre de niños de entre 6 y 12 años que cursan educación primaria en 17 escuelas diferentes, ubicadas en distintas zonas del área metropolitana de Monterrey, de 1998 a 2008. Resultados. Se obtuvieron niveles séricos de 9.6 ± 3.0 (μg/dL rango de 3.18 a 20.88) en 1998 y de 4.5±4.8 μg/dL (rango de 3.3 a 53.7) en 2008, lo que mostró una disminución de 2.1 veces en nivel de Pb (p menor que 0.01). Conclusiones. La reducción de los niveles séricos de Pb demuestran los mejores controles ambientales e industriales y probablemente el éxito de retirar el Pb de la gasolina durante los años noventa.
The Monterrey Metropolitan Area (MMA) is the third largest urban area in Mexico. Its population i... more The Monterrey Metropolitan Area (MMA) is the third largest urban area in Mexico. Its population is around 4 million and the vehicle fleet around 1.6 million, being the metropolitan zone with more vehicles per capita in Mexico. Industry, commerce and population are increasing fast in the MMA. Traffic activities are saturating the city and the introduction of used vehicles from the U.S. will increase the fleet and may have an important contribution in emissions. The emission inventory of the MMA has not been actualized since 1995 and only an aggregated emission inventory by municipality was published in 1999. In this work we present and discuss the results of the 2005 mobile source emission inventory. The MMA vehicle fleet was classified in accordance with the Mobile6.2 Mexico model. This is the most recent model developed for use in Mexico to estimate mobile source emissions. The results of the study show that about 14% of vehicles are from 1981 and before, 51% are in the range 1982-1999, and only 35 % are models 2000 to 2006. The 2006 models considered were sold at the end of 2005. We calculated emissions of CO, NO, SO 2, VOCs, PM 10 , PM 2.5 , NH 3 and CO 2. The results show that more than 6.3 millions of tons of CO2 were emitted and 0.58 million tons of the other pollutants (84.5% of CO, 9.6% of VOCs, 5.45% of NO and the rest of the other pollutants). Private vehicles (sedans and SUVs) contribute with 63.9% of the emissions and public transportation vehicles (taxis and buses) with 20.9%. Important findings are that vehicles 1987 and before contribute with 60% of the CO emissions and with almost 70% VOCs emissions. We estimate that the introduction of 300 thousand used vehicles may have an impact on emissions in the order of 12.7%.
The Monterrey Metropolitan Area (MMA) is the third largest urban area in Mexico. Its population i... more The Monterrey Metropolitan Area (MMA) is the third largest urban area in Mexico. Its population is around 4 million and the vehicle fleet around 1.6 million, being the metropolitan zone with more vehicles per capita in Mexico. Industry, commerce and population are increasing fast in the MMA. Traffic activities are saturating the city and the introduction of used vehicles from the U.S. will increase the fleet and may have an important contribution in emissions. The emission inventory of the MMA has not been actualized since 1995 and only an aggregated emission inventory by municipality was published in 1999. In this work we present and discuss the results of the 2005 mobile source emission inventory. The MMA vehicle fleet was classified in accordance with the Mobile6.2 Mexico model. This is the most recent model developed for use in Mexico to estimate mobile source emissions. The results of the study show that about 14% of vehicles are from 1981 and before, 51% are in the range 1982-...
Salud pública de México
To establish the blood lead concentration and associated risk factors in schoolchildren during 19... more To establish the blood lead concentration and associated risk factors in schoolchildren during 1998 and 2008. A blood lead screening was conducted in schoolchildren of 6-12 years of age, enrolled in 17 elementary schools of the metropolitan area of Monterrey, México, during 1998 and 2008. The mean blood lead level were 9.6 ± 3.0 (µg/dL range of 3.18 to 20.88) in 1998 and 4.5±4.8 µg/dL (range of 3.3 to 53.7) showing a 2.1-times reduction in blood lead levels (p<0.01). This reduction in blood lead levels demonstrate environmental and industrial control improvements and the benefits of fading out the leaded gasoline during the 1990's.
Journal of Environmental Engineering, 2015
ABSTRACT Mobile-source emission inventories in countries such as Mexico still require empirical d... more ABSTRACT Mobile-source emission inventories in countries such as Mexico still require empirical data to complement modeling tools because these tools are based on few local observations. In this study, emission factors (EFs) were determined for 10 light-duty gasoline-powered vehicles as a function of cruising speed under real-world driving conditions typical of the Monterrey metropolitan area, the third largest urban center in Mexico. Greater variability in the EF was found when the vehicles were operated at lower speeds, specifically at 10 km/h ; however, above 40 km/h , the changes were marginal. Engine size was the factor that most influenced the emissions of CO 2 , which were significantly greater in vehicles with an engine size above 2 L. A reduction trend in the CO-to-NO x ratio of newer model vehicles was observed. Upon comparison of the experimental results with the results obtained from the MOBILE6.2-Mexico and the MOVES 2010a models, it was determined that the latter model better described the values of the EFs, the emission profile as a function of speed, and the CO-to-NO x ratio of the tailpipe gases. Read More: http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EE.1943-7870.0000935
Revista Panamericana de Salud Pública, 2009
Journal of the Air & Waste Management Association, 2012
The Monterrey Metropolitan Area (MMA) has shown a high concentration of PM2.5 in its atmosphere s... more The Monterrey Metropolitan Area (MMA) has shown a high concentration of PM2.5 in its atmosphere since 2003. The contribution of possible sources of primary PM2.5 and its precursors is not known. In this paper we present the results of analyzing the chemical composition of sixty 24-hr samples of PM2.5 to determine possible sources of PM2.5 in the MMA. The samples were collected at the northeast and southeast of the MMA between November 22 and December 12, 2007, using low-volume devices. Teflon and quartz filters were used to collect the samples. The concentrations of 16 airborne trace elements were determined using x-ray fluorescence (XRF). Anions and cations were determined using ion chromatography. Organic carbon (OC) and elemental carbon (EC) were determined by thermal optical analysis. The results show that Ca had the maximum mean concentration of all elements studied, followed by S. Enrichment factors above 50 were calculated for S, Cl, Cu, Zn, Br and Pb. This indicates that these elements may come from anthropogenic sources. Overall, the major average components of PM2.5 were OC (41.7%), SO4(2-) (22.9%), EC (7.4%), crustal material (11.4%), and NO3- (12.6%), which altogether accounted for 96% of the mass. Statistically, we did not find any difference in SO4(2-) concentrations between the two sites. The fraction of secondary organic carbon was between 24% and 34%. The results of the factor analysis performed over 10 metals and OC and EC show that there are three main sources of PM2.5: crustal material and vehicle exhaust; industrial activity; and fuel oil burning. The results show that SO4(2-), OC, and crustal material are important components of PM2.5 in MMA. Further work is necessary to evaluate the proportion of secondary inorganic and organic aerosol in order to have a better understanding of the sources and precursors of aerosols in the MMA.
Journal of Petroleum Science and Engineering, 1995
Accurate estimates of multiphase flow functions (relative permeability and capillary pressure) ar... more Accurate estimates of multiphase flow functions (relative permeability and capillary pressure) are necessary for reliable prediction of oil recovery from a reservoir and nonaqueous phase (NAPL) contaminants from aquifers. Current methods of estimating two-phase relative permeabilities from unsteady state displacement experiments are based on Buckley-Leverett model. This model assumes that the medium is homogeneous, flow is one-dimensional and capillary effects
Journal of Petroleum Science and Engineering, 2010
Reservoir relative permeability and capillary pressure, as a function of saturation, is important... more Reservoir relative permeability and capillary pressure, as a function of saturation, is important for assessing reservoir hydrocarbon recovery, selecting the well completion method, and determining the production strategy because they are fundamental inputs to reservoir simulation for predicting lifetime production of a well. Estimation of relative permeability and capillary pressure curves at reservoir conditions is also an important task for successful planning of waterflooding and enhanced oil recovery. The relative permeability and capillary pressure data estimated from core analysis might cause concern regarding representativeness, and adjustments are typically necessary for successful production forecasting. This paper proposes a new method to obtain relative permeability and capillary pressure curves with downhole pressure-transient analysis (PTA) of mini-drillstem tests (miniDSTs) and well log-derived saturations. The new approach was based on performing miniDSTs in the free water, oil, and oil-water transition zones. Analyses of the miniDST buildup tests provided absolute formation permeability, endpoints of relative permeability to both oil and water, and curvature of the relative permeability data. Additionally, resistivity, dielectric, and nuclear magnetic resonance (NMR) logs were used to determine irreducible water, residual oil, and transition zone saturations. Combining these downhole measurements provided the relative permeability and capillary pressure curves.
AGU Spring …, 2007
Results of VOCs speciation from industrial steam boiler stacks located in Naucalpan are presented... more Results of VOCs speciation from industrial steam boiler stacks located in Naucalpan are presented and discussed. This municipality is located north of the Metropolitan Zone of the Valley of Mexico (MZVM). Speciation of VOCs is important to generate information about sources of pollution, to update emission inventories, to study the dynamics of pollutants in the atmosphere, and to estimate possible
scerp.org
The Four-state Region (FSR), as defined by the binational Border 2012 Environmental Program, incl... more The Four-state Region (FSR), as defined by the binational Border 2012 Environmental Program, includes those portions of the Mexican states of Tamaulipas, Nuevo León, and Coahuila within 100 kilometers (km) of the international border and the counties of Texas that fall ...
In this essay, we address the broad issue of environmental security in the U.S.-Mexico border reg... more In this essay, we address the broad issue of environmental security in the U.S.-Mexico border region. The heart of the paper is an examination of the two aspects of environment that are most closely related to human health and well-being: the region's water resources and its air quality. In order to frame our discussion in a context that considers the area's security, we begin by offering our perspective on how to interpret that term so that it can be applied meaningfully to the region's environment. As the next section argues, our understanding of security is expansive, allowing us to speak directly to environmental concerns, thus leaving to others questions of militarization, immigration, drug trafficking, and enforcement. 1. Environment and security: A post-realist perspective Environment and security in the U.S.-Mexico border region-and in any transboundary regionare closely intertwined. Each may and usually does affect the other. Environmental processes in one country, such as droughts, floods, sewage flows, and air pollution, may become serious enough to harm the neighboring country. Conversely, one nation's security-protection actions such as militarization, drug interdiction, fencing, and patrolling for cross-border immigrants can adversely impact the other nation's environment and natural resources. This interrelationship is further complicated by a deeper distinction between hard "traditionalist" or "realist" views of national security on the one hand-and softer, alternative, "nontraditionalist" or "post-realist" interpretations on the other hand. Adherents of the realist, or neo-Hobbesian school of thought see security as a critical part of a nation's sovereignty and therefore as a fundamental, absolute right, with an obligation to preserve it at any cost. According to this interpretation, arising from age-old competition for territory and resources, the concept of "national security" is used to justify maintenance of armies, the development of new weapons systems, and the manufacture of armaments. Military strength-and in recent history, economic power, as well-is the trump card and the nation that possesses the greatest measure of it earns the right to protect itself and its interests absolutely. This perspective prevailed across the globe until the collapse of the Soviet Union and the ensuing end of the Cold War (Dalby, 1992; A. Dinar, 2000). Realists examining environment and security in the U.S.-Mexico case would undoubtedly be most interested in instances where conflicts threaten stability and well-being in one of the states. Salient illustrations include such events as Mexico's delay during the drought of the mid-2000s in meeting treaty obligations to supply critical water to the Rio Grande/Río Bravo; the United States' decision to line the All-American Canal, depriving Mexican farmers of crossborder seepage; and the border security wall's flood causation in Nogales, Sonora, in 2008. Realists would view such instances as serious assaults on their nation's security and would advocate forceful, unilateral measures to impose solutions. But by the late 1970s and early 1980s, although the Cold War still raged, a number of writers-Lester R. Brown was among the vanguard-challenged the realist view of international relations and began in effect "rethinking security" (Brown, 1997; Ullman, 1983; Dalby, 1992). In the early debates, the non-traditionalists argued for a radical expansion of the concept of security to include social, economic, demographic, agricultural, and natural-resources-related matters. Among those at the forefront of this movement to "securitize" environmental issues 1 (Liverman, 2009) were scholars writing about environmental change. Norman Myers and Jessica Mathews, both writing in 1989, were among the early proponents of this view. They saw clearly that because security is contingent on stability and peace, environmental problems and population growth were critical aspects of national security (Myers, 1989; Mathews, 1989) 2. Appreciating the nuances of the rapidly changing relationship between humanity and natural systems and resources, Brown, Myers, Mathews, and other non-traditionalists recognized tradeoffs between security and other values. One important result of this insight was a rise in the importance of environmental issues and the consequent attention to cooperative approaches to transboundary conflicts (A. Dinar, 2010, forthcoming). In this vein, Aaron Wolf, in a seminal 1998 essay (and in a decade of work since), effectively refuted the notion that international water conflicts will inescapably lead to water wars; he demonstrates that historically, cooperation on transboundary waterways disputes has been far and away the prevalent outcome for more than two millennia (Wolf, 1998; 2007; Campbell and Weitz, 2007a). These findings are relevant for the U.S.-Mexico border region. In the years since the initial redefinition of security, writers have continued broadening the term to encompass food security and poverty, climate variability and change, water security, and energy. This more holistic conception of security underlines environmental problems that threaten the health and wellbeing of individuals or economic security of countries (Falkenmark, 2000). The topic water and security has arisen as byproduct of the growing interest in environment and security. Expanding the definition security yet further, Karen O'Brien and Robin Leichenko (2000) proposed a linkage of globalization and climate change, terming the risk from those two combined forces, "double exposure." Through the work of the Global Environmental Change and Human Security [GECHS] project and other efforts, this initial pairing has grown to be multidimensional. This line of reasoning links multiple forces such as globalization, energy demand, poverty, disease, and conflict, which acting in concert, could severely impact communities, society, environment, and stability-in other words, by definition, national security. This more comprehensive line of thinking has been growing. 3 The environmental-human security dimensions are in fact the reason behind the establishment of the United Nations Institute for Environment and Human Security (UNU-EHS) in 2004, under the United Nations University umbrella. For UNU-EHS (2005, p. 3) safeguarding human security requires a new approach, and better knowledge of many interrelated variables-social, political, economic, technological and environmental-which determine the impact of extreme events
Paso del Norte Air …, 2005
Although far from comprehensive with regard to temporal and spatial coverage, the first geographi... more Although far from comprehensive with regard to temporal and spatial coverage, the first geographic information system (GIS)-referenced database on Paso del Norte air quality parameters and impacts is already facilitating development of a variety of advanced models, including diagnostic meteorological models and particulate matter (PM) source and receptor models. When used in conjunction with each other, these models shed light on some of the complex atmospheric transport, reaction, and deposition processes that have confounded past attempts at understanding and predicting Paso del Norte air quality problems in general and fluctuations in ambient PM composition and concentrations in particular.
The Mexico-United States border area has become an increasingly important region due to its comme... more The Mexico-United States border area has become an increasingly important region due to its commercial, industrial and urban growth. As a result, environmental concerns have risen. Treaties like the North American Free Trade Agrement (NAFTA) have further motivated the development of environmental impact assessment in the area. Of particular concern is air quality, and how the activities on both sides of the border contribute to its degradation. This paper presents results of applying a three-dimensional photochemical airshed model to study air pollution dynamics along the Mexico-United States border. In addition, studies were conducted to assess how size resolution impacts the model performance. The model performed within acceptable statistic limits using 12.5 x 12.5 km 2 grid cells, and the benefits using finer grids were limited. Results were further used to assess the influence of grid-cell size on the modeling of control strategies, where coarser grids lead to significant loss of information.
AIChE Journal, 1996
This volume contains 102 papers presented at the National Heat Transfer Symposium of Japan. They ... more This volume contains 102 papers presented at the National Heat Transfer Symposium of Japan. They are divided into numerous sections, the titles of which include: enhancement of convective heat transfer; radiation heat transfer; modelling and numerical analysis of two-phase flow; visualization and measurement of twophase flow; film boiling; heat exchangers; heat transfer in combustion; heat pumps and refrigeration.