Speed limits and their effect on air pollution in Mexico City: A quasi-experimental study.

Speed limits are an evidence-based intervention to prevent traffic collisions and deaths, yet their impact on air pollution in cities is understudied. The objective of this study was to investigate the association between lower speed limits and air pollution. We leverage the introduction of a new road safety policy in Mexico City in December 2015 which lowered speed limits, increased fines, and installed speed radars to enforce compliance. We tested whether the policy had an impact on particulate matter (PM2.5) and nitrogen dioxide (NO2) at the city level, and whether air-quality monitoring stations' proximity to speed radars moderated this effect due to more acceleration and deceleration around radars. NO2 and PM2.5 concentrations from January 2014 to December 2018 were obtained from the National System of Air Quality Information. Air-quality monitoring stations were classified as in close-proximity or far-from-speed radars. Interrupted time series analyses were conducted for each outcome separately, using linear mixed models and adjusting for seasonality and time-varying confounders: registered vehicles, temperature, wind-speed and relative humidity. The results suggest improvement in both contaminants after the speed limits policy. For NO2, the pre-policy trend was flat, while the post-policy trend showed a decline in concentrations of 0.04 ppb/week. For PM2.5, concentrations were increasing pre-policy by 0.08 µg/m3 per week, then this trend flattened in the post-policy period to a weekly, non-significant, increase of 0.03 µg/m3 (p = 0.08). Air-quality monitors' proximity to speed radars did not moderate the effect of the policy on either of the pollutants. In conclusion, the speed limits policy implemented in Mexico City in 2015 was associated with improvements in air pollution.

Ambient nitrogen dioxide in 47 187 neighbourhoods across 326 cities in eight Latin American countries: population exposures and associations with urban features.

BACKGROUND: Health research on ambient nitrogen dioxide (NO2) is sparse in Latin America, despite the high prevalence of NO2-associated respiratory diseases in the region. This study describes within-city distributions of ambient NO2 concentrations at high spatial resolution and urban characteristics associated with neighbourhood ambient NO2 in 326 Latin American cities. METHODS: We aggregated estimates of annual surface NO2 at 1 km2 spatial resolution for 2019, population counts, and urban characteristics compiled by the SALURBAL project to the neighbourhood level (ie, census tracts). We described the percentage of the urban population living with ambient NO2 concentrations exceeding WHO air quality guidelines. We used multilevel models to describe associations of neighbourhood ambient NO2 concentrations with population and urban characteristics at the neighbourhood and city levels. FINDINGS: We examined 47 187 neighbourhoods in 326 cities from eight Latin American countries. Of the roughly 236 million urban residents observed, 85% lived in neighbourhoods with ambient annual NO2 above WHO guidelines. In adjusted models, higher neighbourhood-level educational attainment, closer proximity to the city centre, and lower neighbourhood-level greenness were associated with higher ambient NO2. At the city level, higher vehicle congestion, population size, and population density were associated with higher ambient NO2. INTERPRETATION: Almost nine out of every ten residents of Latin American cities live with ambient NO2 concentrations above WHO guidelines. Increasing neighbourhood greenness and reducing reliance on fossil fuel-powered vehicles warrant further attention as potential actionable urban environmental interventions to reduce population exposure to ambient NO2. FUNDING: Wellcome Trust, National Institutes of Health, Cotswold Foundation.

Long-term exposure to ambient fine particulate matter and carotid intima media thickness at bilateral, left and right in adults from Mexico City: Results from GEA study.

BACKGROUND: PM2.5 exposure has been associated with intima-media thickness (cIMT) increase. However, very few studies distinguished between left and right cIMT in relation to PM2.5 exposure. AIM: To evaluate associations between chronic exposure to PM2.5 and cIMT at bilateral, left, and right in adults from Mexico City. METHODS: This study comprised 913 participants from the control group, participants without personal or family history of cardiovascular disease, of the Genetics of Atherosclerosis Disease Mexican study (GEA acronym in Spanish), recruited at the Instituto Nacional de Cardiología Ignacio Chávez from June 2008 to January 2013. To assess the associations between chronic exposure to PM2.5 (per 5 µg/m3 increase) at different lag years (1-4 years) and cIMT (bilateral, left, and right) we applied distributed lag non-linear models (DLNMs). RESULTS: The median and interquartile range for cIMT at bilateral, left, and right, were 630 (555, 735), 640 (550, 750), and 620 (530, 720) µm, respectively. Annual average PM2.5 exposure was 26.64 µg/m3, with median and IQR, of 24.46 (23.5-25.46) µg/m3. Results from DLNMs adjusted for age, sex, body mass index, low-density lipoproteins, and glucose, showed that PM2.5 exposure for year 1 and 2, were positively and significantly associated with right-cIMT [6.99% (95% CI: 3.67; 10.42) and 2.98% (0.03; 6.01), respectively]. Negative associations were observed for PM2.5 at year 3 and 4 and right-cIMT; however only year 3 was statistically significant [-2.83% (95% CI: 5.12; -0.50)]. Left-cIMT was not associated with PM2.5 exposure at any lag year. The increase in bilateral cIMT followed a similar pattern as that observed for right-cIMT, but with lower estimates. CONCLUSIONS: Our results suggest different susceptibility between left and right cIMT associated with PM2.5 exposure highlighting the need of measuring both, left and right cIMT, regarding ambient air pollution in epidemiological studies.

Use of self-help groups by people living with HIV in Central America.

Self-help groups (SHGs) for people living with HIV (PLHIV) are organizations created by the community to provide individuals with security, affection, improved self-esteem, and a sense of belonging. However, SHGs have also been used by the government to help implement HIV control policies. This study aimed to identify the characteristics associated with the use of SHGs by PLHIV and the routes and displacement patterns adopted by users. An analytical cross-sectional study was conducted based on data collected in six Central American countries during 2012. Using a list of SHGs, a random sampling was conducted in two stages. Firstly, the SHGs were selected. Then, the selected SHGs were visited and every third user who attended the SHG was surveyed. Logistic regression models were used to identify the characteristics associated with the use of SHGs and with attending the nearest SHGs. A spatial analysis was performed to identify the routes followed by users to reach the SHGs from their home communities. We found that the characteristics significantly associated with higher odds of SHG usage were country of residence and schooling level. The average and median distances traveled by users to attend SHGs were 20 and 5 kilometers, respectively. PLHIV do not use the SHGs closest to their locality, perhaps for fear of stigma and discrimination. We recommend that research on this topic use a mixed qualitative-quantitative methodology to better understand utilization decisions, user expectations, and the degree to which these are being met.

Prenatal Co-Exposure to Manganese, Mercury, and Lead, and Neurodevelopment in Children during the First Year of Life.

Lead (Pb), mercury (Hg), and manganese (Mn) are neurotoxic, but little is known about the neurodevelopmental effects associated with simultaneous prenatal exposure to these metals. We aimed to study the associations of Pb, Hg, and Mn prenatal levels (jointly and separately) with neurodevelopment in the first year of life. Methods: Pb, Hg, and Mn blood lead levels were measured in 253 pregnant women. Their offspring's neurodevelopment was assessed through the Bayley Scale of Infant Development III® at one, three, six, and twelve months. The metals' mean blood levels (µg/L) were Pb = 11.2, Hg = 2.1, and Mn = 10.2. Mean language, cognitive, and motor development scores of the infants at each age were between low-average and average. Multilevel models' results showed that language development coefficients of the offspring decreased by 1.5 points per 1 µg/dL increase in maternal blood lead levels (p = 0.002); the magnitude of the aforementioned association increased in children with maternal blood Mn < 9.6 µg/L (ß = -1.9, p = 0.003) or Hg > 1.9 µg/L (ß = -1.6, p = 0.013). Cognitive and motor development had negative associations with maternal blood Pb levels; the latter was statistically significant when the interaction term between Pb, Mn, and Hg was included (ß = -0.037, p = 0.03). Prenatal exposure to low Pb levels may impair infants' neurodevelopment in the first year of life, even more so if they are exposed to Hg or deficient in Mn.

Long-Term Exposure to Ozone and Fine Particulate Matter and Risk of Premature Coronary Artery Disease: Results from Genetics of Atherosclerotic Disease Mexican Study.

(1) Background: Epidemiological studies have identified associations between fine particulate matter (PM2.5) and ozone exposure with cardiovascular disease; however, studies linking ambient air pollution and premature coronary artery disease (pCAD) in Latin America are non-existing. (2) Methods: Our study was a case−control analysis nested in the Genetics of Atherosclerotic Disease (GEA) Mexican study. We included 1615 participants (869 controls and 746 patients with pCAD), recruited at the Instituto Nacional de Cardiología Ignacio Chávez from June 2008 to January 2013. We defined pCAD as history of myocardial infarction, angioplasty, revascularization surgery or coronary stenosis > 50% diagnosed before age 55 in men and age 65 in women. Controls were healthy individuals without personal or family history of pCAD and with coronary artery calcification equal to zero. Hourly measurements of ozone and PM2.5 from the Atmospheric Monitoring System in Mexico City (SIMAT in Spanish; Sistema de Monitero Atmosférico de la Ciudad de México) were used to calculate annual exposure to ozone and PM2.5 in the study participants. (3) Results: Each ppb increase in ozone at 1-year, 2-year, 3-year and 5-year averages was significantly associated with increased odds (OR = 1.10; 95% CI: 1.03−1.18; OR = 1.17; 95% CI: 1.05−1.30; OR = 1.18; 95% CI: 1.05−1.33, and OR = 1.13; 95% CI: 1.04−1.23, respectively) of pCAD. We observed higher risk of pCAD for each 5 µg/m3 increase only for the 5-year average of PM2.5 exposure (OR = 2.75; 95% CI: 1.47−5.16), compared to controls. (4) Conclusions: Ozone exposure at different time points and PM2.5 exposure at 5 years were associated with increased odds of pCAD. Our results highlight the importance of reducing long-term exposure to ambient air pollution levels to reduce the burden of cardiovascular disease in Mexico City and other metropolitan areas.

Short term exposure to ambient air pollutants and cardiovascular emergency department visits in Mexico city.

Available data on the acute cardiovascular effect of ambient air pollution (AAP) in Latin America is limited considering that over 80% of its 1 billion inhabitants live in urban settlements with poor air quality. The study aim was to evaluate the association between Cardiovascular Emergency Department Visits (CEDVs) and AAP in Mexico City from 2016 to 2019 using generalized additive models with distributed lags to examine the percentage change of CEDVs and a backward approach of time-series model to calculate attributable fractions. A total of 48,891 CEDVs were recorded in a period of 1019 days. We estimated a significant percentage increase for each 10 µg/m3 of PM10 at Lag0-5 (2.8%, 95%CI 0.6-5.0), PM2.5 at Lag0-6 (3.7%, 95%CI 0.1-7.6), O3 at Lag0-5 (1.1%, 95%CI 0.2-2.0), NO2 at Lag0-4 (2.5%, 95%CI 0.3-4.7) and for each 1 mg/m3 of CO at Lag0 (6.6%, 95%CI 0.3-13.2). Overall, 10.3% of CEDVs in Mexico City may be related to PM10 exposure, 9.5% to PM2.5, 10.3% to O3, 11% to NO2 and 5.7% to CO. AAP significantly increase cardiovascular morbidity impacting on emergency medical services.

Air pollution exposure and incidence of type 2 diabetes in women: A prospective analysis from the Mexican Teachers' Cohort.

BACKGROUND: Air pollution is a risk factor for type 2 diabetes (T2D). However, scarse longitudinal studies have evaluated this association in low- and middle-income countries, where 80% of the worldwide cases of T2D occur. OBJECTIVE: Our aim was to estimate the association between PM2.5 and NO2 exposure and incident T2D, in the Mexican Teachers' Cohort (MTC). METHODS: We selected a subsample of female teachers from the MTC from Mexico City metropolitan area (MCMA), recruited in 2008 and with active follow-up every three years. We assigned the monthly time-weighted exposures (PM2.5 and NO2) using home and work addresses, until failure, censoring or death. We developed two high resolution (1 × 1-km) spatiotemporal predictive generalized additive models of PM2.5 and NO2. Incident diabetes was identified through self-report and two administrative databases of registered diabetes patients. We fitted time-varying Cox models to estimate hazard ratios of the relation between PM2.5 and NO2 and incident T2D, adjusting for confounding variables that were identified using a causal model. RESULTS: A total of 13,669 teachers were followed-up for a maximum of 11.5 years, over which 996 incident T2D cases (88 cases per 100,000 person-months) occurred. Incident T2D increased by 72% (HR = 1.72 [1.47-2.01]) for each 10 µg/m3 increase of PM2.5, and 52% for each 10 ppb of NO2 (HR = 1.52 [1.37-1.68]). DISCUSSION: Mid-term exposure to PM2.5 and NO2 was associated with a higher risk of T2D after adjusting for indoor wood smoke, socioeconomic status, and physical activity. These associations were attenuated in two-pollutant models but remained positive when evaluated long-term exposure. This is the first prospective study to evaluate T2D risk by exposure to both pollutants, PM2.5 and NO2 in a population from an upper middle-income country in the Americas.

Use of self-help groups by people living with HIV in Central America / Uso de grupos de autoayuda por personas que viven con el VIH en América Central / Uso de grupos de autoajuda por pessoas vivendo com HIV na América Central

Self-help groups (SHGs) for people living with HIV (PLHIV) are organizations created by the community to provide individuals with security, affection, improved self-esteem, and a sense of belonging. However, SHGs have also been used by the government to help implement HIV control policies. This study aimed to identify the characteristics associated with the use of SHGs by PLHIV and the routes and displacement patterns adopted by users. An analytical cross-sectional study was conducted based on data collected in six Central American countries during 2012. Using a list of SHGs, a random sampling was conducted in two stages. Firstly, the SHGs were selected. Then, the selected SHGs were visited and every third user who attended the SHG was surveyed. Logistic regression models were used to identify the characteristics associated with the use of SHGs and with attending the nearest SHGs. A spatial analysis was performed to identify the routes followed by users to reach the SHGs from their home communities. We found that the characteristics significantly associated with higher odds of SHG usage were country of residence and schooling level. The average and median distances traveled by users to attend SHGs were 20 and 5 kilometers, respectively. PLHIV do not use the SHGs closest to their locality, perhaps for fear of stigma and discrimination. We recommend that research on this topic use a mixed qualitative-quantitative methodology to better understand utilization decisions, user expectations, and the degree to which these are being met.

Los grupos de autoayuda (GAA) para personas que viven con el VIH (PVVIH) son organizaciones creadas por la comunidad para proporcionarles seguridad, afecto, mejor autoestima y un sentido de pertenencia. Sin embargo, el gobierno también ha utilizado los GAA para ayudar a implementar políticas de control del VIH. Se buscó identificar las características asociadas con el uso de GAA por PVVIH y las rutas y patrones de desplazamiento adoptados por los usuarios. Este es un estudio analítico transversal basado en datos recogidos en seis países centroamericanos en 2012. A través de una lista de GAA, se construyó un muestreo aleatorio de dos etapas. Primero, se seleccionaron los GAA. Luego, los participantes recibieron una visita, y se evaluó cada tercio de ellos. Se utilizaron modelos de regresión logística para identificar las características asociadas al uso y visitas a los GAA más cercanos a los usuarios. Se realizó un análisis espacial para identificar las rutas que los voluntarios tomaron para llegar a los GAA en sus comunidades de origen. Se constató que las características significativamente asociadas con mayores probabilidades de uso de los GAA fueron el país de residencia y la escolaridad. Las distancias medias y medianas recorridas por los usuarios para visitar los GAA fueron de 20 kilómetros y 5 kilómetros, respectivamente. Las PVVIH no utilizan los GAA más cercanos a su casa, tal vez por miedo al estigma y a la discriminación. Se necesitan investigaciones sobre este tema que utilicen una metodología mixta cualitativa-cuantitativa para comprender mejor las decisiones de uso, las expectativas de los usuarios y el grado en que se están atendiendo.

Grupos de autoajuda (GAAs) para pessoas vivendo com HIV (PVHIV) são organizações criadas pela comunidade para proporcioná-los segurança, afeto, melhor autoestima e senso de pertencimento. No entanto, o governo também tem usado os GAAs para ajudar a implementar políticas de controle do HIV. Buscamos identificar as características associadas ao uso de GAAs por PVHIV e as rotas e padrões de deslocamento adotados pelos usuários. Este é um estudo analítico transversal realizado com base em dados coletados em seis países da América Central em 2012. Através de uma lista de GAAs, uma amostragem aleatória em dois estágios foi construída. Em primeiro lugar, os GAAs foram selecionados. Em seguida, eles foram visitados e cada terceiro de seus participantes foi avaliado. Foram utilizados modelos de regressão logística para identificar as características associadas ao uso e às visitas aos GAAs mais próximos aos usuários. Foi realizada uma análise espacial para identificar as rotas que voluntários tomavam para chegar aos GAAs em suas comunidades de origem. Verificamos que as características significativamente associadas com maiores chances de uso dos GAAs foram país de residência e escolaridade. As distâncias médias e medianas percorridas por usuários para visitar os GAAs foram de 20 quilômetros e 5 quilômetros, respectivamente. As PVHIV não utilizam os GAAs mais próximos de onde moram, talvez por medo de estigma e discriminação. Recomendamos que as pesquisas sobre este tema utilizem uma metodologia qualitativa-quantitativa mista para entender melhor as decisões de utilização, as expectativas dos usuários e o grau em que eles estão sendo atendidos.

Health and Economic Impacts Assessment of O3 Exposure in Mexico.

Health effects related to exposure to air pollution such as ozone (O3) have been documented. The World Health Organization has recommended the use of the Sum of O3 Means Over 35 ppb (SOMO35) to perform Health Impact Assessments (HIA) for long-term exposure to O3. We estimated the avoidable mortality associated with long-term exposure to tropospheric O3 in 14 cities in Mexico using information for 2015. The economic valuation of avoidable deaths related to SOMO35 exposure was performed using the willingness to pay (WTP) and human capital (HC) approaches. We estimated that 627 deaths (95% uncertainty interval (UI): 227-1051) from respiratory diseases associated with the exposure to O3 would have been avoided in people over 30 years in the study area, which confirms the public health impacts of ambient air pollution. The avoidable deaths account for almost 1400 million USD under the WTP approach, whilst the HC method yielded a lost productivity estimate of 29.7 million USD due to premature deaths. Our findings represent the first evidence of the health impacts of O3 exposure in Mexico, using SOMO35 metrics.

Exposure to PM2.5 and Obesity Prevalence in the Greater Mexico City Area.

Exposure to PM2.5 has been associated with the prevalence of obesity. In the Greater Mexico City Area (GMCA), both are ranked among the highest in the world. Our aim was to analyze this association in children, adolescents, and adults in the GMCA. We used data from the 2006 and 2012 Mexican National Surveys of Health and Nutrition (ENSANUT). Participants' past-year exposure to ambient PM2.5 was assessed using land use terms and satellite-derived aerosol optical depth estimates; weight and height were measured. We used survey-adjusted logistic regression models to estimate the odds ratios (ORs) of obesity (vs. normal-overweight) for every 10 µg/m3 increase in annual PM2.5 exposure for children, adolescents, and adults. Using a meta-analysis approach, we estimated the overall odds of obesity. We analyzed data representing 19.3 million and 20.9 million GMCA individuals from ENSANUT 2006 and 2012, respectively. The overall pooled estimate between PM2.5 exposure and obesity was OR = 1.96 (95% CI: 1.21, 3.18). For adolescents, a 10 µg/m3 increase in PM2.5 was associated with an OR of 3.53 (95% CI: 1.45, 8.58) and 3.79 (95% CI: 1.40, 10.24) in 2006 and 2012, respectively. More studies such as this are recommended in Latin American cities with similar air pollution and obesity conditions.

Ambient fine particulate matter in Latin American cities: Levels, population exposure, and associated urban factors.

BACKGROUND: Exposure to particulate matter (PM2.5) is a major risk factor for morbidity and mortality. Yet few studies have examined patterns of population exposure and investigated the predictors of PM2.5 across the rapidly growing cities in lower- and middle-income countries. OBJECTIVES: Characterize PM2.5 levels, describe patterns of population exposure, and investigate urban factors as predictors of PM2.5 levels. METHODS: We used data from the Salud Urbana en America Latina/Urban Health in Latin America (SALURBAL) study, a multi-country assessment of the determinants of urban health in Latin America, to characterize PM2.5 levels in 366 cities comprising over 100,000 residents using satellite-derived estimates. Factors related to urban form and transportation were explored. RESULTS: We found that about 172 million or 58% of the population studied lived in areas with air pollution levels above the defined WHO-AQG of 10 µg/m3 annual average. We also found that larger cities, cities with higher GDP, higher motorization rate and higher congestion tended to have higher PM2.5. In contrast cities with higher population density had lower levels of PM2.5. In addition, at the sub-city level, higher intersection density was associated with higher PM2.5 and more green space was associated with lower PM2.5. When all exposures were examined adjusted for each other, higher city per capita GDP and higher sub-city intersection density remained associated with higher PM2.5 levels, while higher city population density remained associated with lower levels. The presence of mass transit was also associated with lower PM2.5 after adjustment. The motorization rate also remained associated with PM2.5 and its inclusion attenuated the effect of population density. DISCUSSION: These results show that PM2.5 exposures remain a major health risk in Latin American cities and suggest that urban planning and transportation policies could have a major impact on ambient levels.

Revisión rápida: contaminación del aire y morbimortalidad por Covid-19 / Quick review: air pollution and morbi-mortality by Covid-19

Resumen Objetivo: Analizar la evidencia sobre la relación entre la contaminación del aire y un riesgo mayor de morbimortalidad por Covid-19. Material y métodos: Se utilizó una adaptación de la metodología de revisiones rápidas de Cochrane. La búsqueda se realizó en PubMed y MedRxiv y se limitó hasta el 28 y 26 de abril, respectivamente. Los títulos y resúmenes fueron revisados por cinco investigadores que, a su vez, revisaron los textos completos de la selección final. Resultados: Se encontraron 450 manuscritos, 15 cumplieron los criterios de inclusión. La evidencia encontrada reporta que la incidencia y el riesgo de morbilidad y mortalidad por Covid-19 se incrementan con la exposición crónica y aguda a la contaminación del aire, particularmente a material particulado (PM2.5, PM10) y dióxido de nitrógeno. Conclusiones: Se requieren más estudios especialmente en ciudades latinoamericanas. Es necesario fortalecer las recomendaciones en las ciudades con mayores niveles de contaminantes y reducir sus emisiones.

Abstract Objective: To analyze the evidence on the relationship between air pollution and an increased risk of morbidity and mortality from Covid-19. Materials and methods: An adaptation of the Cochrane rapid review methodology was used. The search was performed in PubMed and MedRxiv and was limited until April 28 and 26, respectively. The titles and abstracts were reviewed by five researchers who, in turn, reviewed the full texts of the final selection. Results: 450 manuscripts were found, 15 met the inclusion criteria. The evidence reports that the incidence and risk of morbidity and mortality from Covid-19 increase with chronic and acute exposure to air pollution, particularly to particulate matter (PM2.5, PM10) and nitrogen dioxide. Conclusions: More studies are required especially in Latin American cities. It is necessary to strengthen the recommendations in cities with higher levels of pollutants and to reduce their emissions.

Assessing the Influence of Socioeconomic Status and Air Pollution Levels on the Public Perception of Local Air Quality in a Mexico-US Border City.

Air pollution in developing countries is a growing concern. It is associated with urbanization and social and economic structures. The understanding of how social factors can influence the perception and the potential impact of air pollution have not been addressed sufficiently. This paper addresses the social vulnerability and exposure to PM10 association and its influence on the air quality perception of residents in Mexicali, a Mexico-US border city. This study used individual variables and population census data, as well as statistical and spatial analyses. A cluster of socially vulnerable populations with high exposure to coarse particulate matter (PM10) was found in the city's peripheral areas. The spatial distribution of the local perception of air quality varied by the exposure zones of the estimated PM10 concentrations. Respondents living in very high exposure areas perceive air quality as "poor," contrarily to a worse perception in areas of intermediate and lower exposure to PM10. Proximity to stationary sources of pollution was associated with a poor perception of air quality. Results also indicate that low household income and poor air quality perceived at the place of residence negatively influences the perceived changes in the air quality over time. The knowledge of chronic health effects related to air pollution was scarce in the sampled population, especially in the areas with very high exposure and high social vulnerability. These findings can serve as a support in local air quality management.

Air pollution and children's respiratory health: a scoping review of socioeconomic status as an effect modifier.

OBJECTIVES: Air pollution is a leading environmental risk, and socioeconomic status (SES) is postulated as an effect modifier, especially in children. There is a growing interest in exploring this modifier. The present manuscript reviews SES as an effect modifier in children's respiratory health. METHODS: A search in the PubMed and SCOPUS databases was conducted in September 2017 to identify studies with the inclusion criteria of being centred on children, respiratory outcomes, air pollutants and SES measurement. RESULTS: A total of 17 studies were included. Twelve used single SES variables, and the remaining studies included composite SES indices. Household income (9) and parental education (8) were frequently evaluated. The significance of the effect modifier was found in nine studies that demonstrated a higher risk for individuals living in a lower SES. Sources of heterogeneity included SES measurement, health outcomes and geographical aggregation. CONCLUSIONS: The results suggest a higher modification in the effect of SES, generally indicating greater risk for children in lower SES. Children's characteristics need to be more carefully theorized and measured in this area, including the use of transdisciplinary approaches.

Children's acute respiratory symptoms associated with PM2.5 estimates in two sequential representative surveys from the Mexico City Metropolitan Area.

BACKGROUND: Respiratory diseases are a major component of morbidity in children and their symptoms may be spatially and temporally exacerbated by exposure gradients of fine particulate matter (PM2.5) in large polluted urban areas, like the Mexico City Metropolitan Area (MCMA). OBJECTIVES: To analyze the association between satellite-derived and interpolated PM2.5 estimates with children's (≤9 years old) acute respiratory symptoms (ARS) in two probabilistic samples representing the MCMA. METHODS: We obtained ARS data from the 2006 and 2012 National Surveys for Health and Nutrition (ENSaNut). Two week average exposure to PM2.5 was assessed for each household with spatial estimates from a hybrid model with satellite measurements of aerosol optical depth (AOD-PM2.5) and also with interpolated PM2.5 measurements from ground stations, from the Mexico City monitoring network (MNW-PM2.5). We used survey-adjusted logistic regressions to analyze the association between PM2.5 estimates and ARS reported on children. RESULTS: A total of 1,005 and 1,233 children were surveyed in 2006 and 2012 representing 3.1 and 3.5 million children, respectively. For the same years and over the periods of study, the estimated prevalence of ARS decreased from 49.4% (95% CI: 44.9,53.9%) to 37.8% (95% CI: 34,41.7%). AOD-PM2.5 and MNW-PM2.5 estimates were associated with significantly higher reports of ARS in children 0-4 years old [OR2006 = 1.29 (95% (CI): 0.99,1.68) and OR2006 = 1.24 (95% CI: 1.08,1.42), respectively]. We observed positive non-significant associations in 2012 in both age groups and in 2006 for children 5-9 years old. No statistically significant differences in health effect estimates of PM2.5 were found comparing AOD-PM2.5 or MNW-PM2.5 for exposure assessment. CONCLUSIONS: Our findings suggest that PM2.5 is a risk factor for the prevalence of ARS in children and expand the growing evidence of the utility of new satellite AOD-based methods for estimating health effects from acute exposure to PM2.5.

[Trends in the prevalence of ARIs and ADDs in early childhood and associated factors: Ensanut 2012 and 100k.] / Tendencias en la prevalencia de IRA y EDA en la primera infancia y factores asociados: Ensanut 2012 y 100k.

OBJECTIVE: To compare the prevalence of acute respiratory infections (ARI) and acute diarrheal disease (ADD) among children younger than five years of age living in localities with less than 100 000 inhabitants in Encuesta Nacional de Salud y Nutrición (Ensanut) 2012 and Ensanut 100k (2018). In Ensanut 100k, we evaluate the associated factors. MATERIALS AND METHODS: Analysis of both surveys and of the Mexican Meteorological System. RESULTS: The estimated prevalence of ARI was 45.1% in 2012 vs. 32.9% in 2018. The decrease was significant among medium and high-income households. There were no changes in trends for ADD. Among households with lower EC, ARI was associated with roofing material, temperature, and rainy precipitation while ADD was associated with lack of piped water. CONCLUSIONS: The estimated prevalence of ARI has decreased in medium and high income households. Some households and weather conditions are associated with ARI and ADD.

OBJETIVO: Estimar y comparar las prevalencias de infec- ciones respiratorias agudas (IRA) y enfermedades diarreicas agudas (EDA) en menores de cinco años, residentes en localidades con menos de 100 000 habitantes, mediante análisis de la Encuesta Nacional de Salud y Nutrición (Ensanut) 2012 y la Ensanut 100k (2018). En la Ensanut 100k se evaluaron los factores asociados con IRA y EDA. MATERIAL Y MÉTODOS: Análisis de ambas encuestas e información meteorológica de la Comisión Nacional del Agua. RESULTADOS: La prevalencia global estimada de IRA fue de 45.1% en 2012 vs. 32.9% en 2018. La disminución fue significativa en hogares de medianas y mayores capacidades económicas (CE). No se observaron cambios significativos para las EDA. En hogares con menores CE, las IRA se asociaron con material del techo y temperatura y las EDA con privación de agua entubada. CONCLUSIONES: Entre 2012 y 2018, la prevalencia de IRA disminuyó en hogares de medianas y mayores CE. Algunas condiciones de vivienda y meteorológicas se asocian con IRA y EDA.

Tendencias en la prevalencia de IRA y EDA en la primera infancia y factores asociados: Ensanut 2012 y 100k / Trends in the prevalence of ARIs and ADDs in early childhood and associated factors: Ensanut 2012 and 100k

Resumen: Objetivo: Estimar y comparar las prevalencias de infecciones respiratorias agudas (IRA) y enfermedades diarreicas agudas (EDA) en menores de cinco años, residentes en localidades con menos de 100 000 habitantes, mediante análisis de la Encuesta Nacional de Salud y Nutrición (Ensanut) 2012 y la Ensanut 100k (2018). En la Ensanut 100k se evaluaron los factores asociados con IRA y EDA. Material y métodos: Análisis de ambas encuestas e información meteorológica de la Comisión Nacional del Agua. Resultados: La prevalencia global estimada de IRA fue de 45.1% en 2012 vs. 32.9% en 2018. La disminución fue significativa en hogares de medianas y mayores capacidades económicas (CE). No se observaron cambios significativos para las EDA. En hogares con menores CE, las IRA se asociaron con material del techo y temperatura y las EDA con privación de agua entubada. Conclusiones: Entre 2012 y 2018, la prevalencia de IRA disminuyó en hogares de medianas y mayores CE. Algunas condiciones de vivienda y meteorológicas se asocian con IRA y EDA.

Abstract: Objective: To compare the prevalence of acute respiratory infections (ARI) and acute diarrheal disease (ADD) among children younger than five years of age living in localities with less than 100 000 inhabitants in Encuesta Nacional de Salud y Nutrición (Ensanut) 2012 and Ensanut 100k (2018). In Ensanut 100k, we evaluate the associated factors. Materials and methods: Analysis of both surveys and of the Mexican Meteorological System. Results: The estimated prevalence of ARI was 45.1% in 2012 vs. 32.9% in 2018. The decrease was significant among medium and high-income households. There were no changes in trends for ADD. Among households with lower EC, ARI was associated with roofing material, temperature, and rainy precipitation while ADD was associated with lack of piped water. Conclusions: The estimated prevalence of ARI has decreased in medium and high income households. Some households and weather conditions are associated with ARI and ADD.

Quantifying health impacts and economic costs of PM2.5 exposure in Mexican cities of the National Urban System.

OBJECTIVES: To estimate avoidable mortality, potential years of life lost and economic costs associated with particulate matter PM2.5 exposure for 2 years (2013 and 2015) in Mexico using two scenarios of reduced concentrations (i.e., mean annual PM2.5 concentration < 12 µg/m3 and mean annual PM2.5 concentration < 10 µg/m3). METHODS: The health impact assessment method was followed. This method consists of: identification of health effects, selection of concentration-response functions, estimation of exposure, quantification of impacts quantification and economic assessment using the willingness to pay and human capital approaches. RESULTS: For 2013, we included data from 62 monitoring sites in ten cities, (113 municipalities) where 36,486,201 live. In 2015, we included 71 monitoring sites from fifteen cities (121 municipalities) and 40,479,629 inhabitants. It was observed that reduction in the annual PM2.5 average to 10 µg/would have prevented 14,666 deaths and 150,771 potential years of life lost in 2015, with estimated costs of 64,164 and 5434 million dollars, respectively. CONCLUSIONS: Reducing PM2.5 concentration in the Mexican cities studied would reduce mortality by all causes by 8.1%, representing important public health benefits.

Air pollution management and control in Latin America and the Caribbean: implications for climate change.

OBJECTIVE: To assess the status of the legal framework for air quality control in all countries of Latin America and Caribbean (LAC); to determine the current distribution of air monitoring stations and mean levels of air pollutants in all capital and large cities (more than 100 000 inhabitants); and to discuss the implications for climate change and public policymaking. METHODS: From January 2015-February 2016, searches were conducted of online databases for legislation, regulations, policies, and air pollution programs, as well as for the distribution of monitoring stations and the mean annual levels of air pollution in all LAC countries. RESULTS: Only 117 cities distributed among 17 of 33 LAC countries had official information on ground level air pollutants, covering approximately 146 million inhabitants. The annual mean of inhalable particles concentration in most of the cities were over the World Health Organization Air Quality Guidelines; notably, only Bolivia, Peru, and Guatemala have actually adopted the guidelines. Most of the cities did not have information on particulate matter of 2.5 microns or less, and only a few measured black carbon. CONCLUSIONS: The air quality regulatory framework should be updated to reflect current knowledge on health effects. Monitoring and control of ground level pollutants should be extended and strengthened to increase awareness and protect public health. Using the co-benefits of air pollution control for health and climate as a framework for policy and decision-making in LAC is recommended.