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Pollen is one of the primary causes of allergic rhinoconjunctivitis in urban centers. In the present study, the concentrations of 39 different pollens in the Santiago de Chile metropolitan area over the period 2009–2013 are characterized. The pollen was monitored daily using Burkard volumetric equipment. The contribution of each type of pollen and the corresponding time trends are evaluated. The concentrations of the pollens are compared with the established threshold levels for the protection of human health. The results show that the total amount of pollen grains originating from trees, grasses, weeds and indeterminate sources throughout the period of the study was 258,496 grains m-3, with an annual average of 51,699 ± 3,906 grains m-3 year-1. The primary source of pollen is Platanus orientalis, which produces 61.8% of the analyzed pollen. Grass pollen is the third primary component of the analyzed pollen, with a contribution of 5.82%. Among the weeds, the presence of Urticacea (3.74%) is remarkable. The pollination pattern of the trees is monophasic, and the grasses have a biphasic pattern. The trends indicate that the total pollen and tree pollen do not present a time trend that is statistically significant throughout the period of the study, whereas the grass pollen and weed pollen concentrations in the environment present a statistically significant decreasing trend. The cause of this decrease is unclear. The pollen load has doubled over the past decade. When the observed concentrations of the pollens were compared with the corresponding threshold levels, the results indicated that over the period of the study, the pollen concentrations were at moderate, high and very high levels for an average of 293 days per year. Systematic counts of the pollen grains are an essential method for diagnosing and treating patients with pollinosis and for developing forestation and urban planning strategies. [ABSTRACT FROM AUTHOR]

The study examined weekday–weekend differences in ozone, NOx (NO and NO2) and VOC concentrations in Santiago, Chile, from 1999 to 2007. The results provide evidence for the occurrence of an atmospheric phenomenon that produces higher ozone concentrations during weekends despite lower concentrations of ozone precursors. This phenomenon is known as the weekend effect (WE). The overall ozone decrease since the spring of 2004 was a consequence of the implementation of several urban pollution control measures. Although these measures caused a decline in the number of days that exceed the national standard from two-thirds to one-third of summer days, the WE, which became statistically significant beginning in September 2004, could not be eliminated. Furthermore, VOC/NOx ratios decreased during the same period (2004), especially in the most industrialized area of Santiago. Similarly, under these regimes, the VOC/NOx ratios were higher on Sundays than on weekdays and caused higher ozone concentrations on Sundays. [Copyright &y& Elsevier]

High concentration of fine airborne particulates is considered one of the major environmental pollutants in Santiago, the Chilean Capital city, which in 1997 was declared a PM10 saturated zone. To date there is no control of the amounts of fine and coarse aerosols concentrations and the source and chemical characterizations of the PM2.5 particulates in the carbonaceous fractions are not well known even though this fraction could be represented almost the 50% in mass of the PM2.5. In this work, we present for the first time determinations of primary organic aerosol (POA) and secondary organic aerosol composition (SOA) fractions of the total mass of PM2.5 particulates collected in the urban atmosphere of Santiago City. Our purpose is to know the anthropogenic contributions to the formation of SOA. To accomplish this we used the elemental carbon (EC) and organic carbon (OC) determinations developed by automatic monitoring stations installed in the city during the period 2002–2005, with a particular analysis of the summer time occurred in February 2004. Based on the EC tracer method, we have estimated the POA and SOA fraction and our data permit us to estimate the SOA reaching up to 20% of total organic aerosol matter, in good agreement to other measurements observed in large cities of Europe and U.S.A. [Copyright &y& Elsevier]

Introduction: Understanding suicidal ideation and its association with childhood adversity is crucial for preventing suicide. Although the "healthy immigrant effect", whereby immigrants are healthier than the native-born population, has been well documented across studies, little research has examined the presence of such effect on lifetime suicidal ideation (LSI) and its association to early adversity. Objectives: The aim of this study was to compare the prevalence of LSI between the immigrant and native-born population in Chile and explore the association between childhood adversity and suicidal ideation in immigrants. Methods: Data fromtwo cross-sectional health surveys: the Santiago Immigrant Wellbeing Study (STRING, n=1,091; 2019) and the Chilean National Health Survey (ENS2016, n=3,432) were used. Each study usedmultistage probability sampling and estimates were weighted to approximate the distribution of demographic variables in each population. Outcomes included LSI measured by WHOCIDI and an adapted version of the Adverse Childhood Experience Questionnaire. Multivariate logistic regression was employed. Results: indicated that immigrants were less likely to report LSI compared with the native-born population. Moreover, male and female immigrants had lower risk of having SI than native-born counterparts. After controlling for socioeconomic status, social support, and health conditions, childhood adversities predicted an increased risk of LSI in immigrants. No gender differences were found in the effects of childhood adversity on suicidal thoughts. Conclusions: Findings confirm the presence of a healthy immigrant effect in LSI and support a life course perspective, highlighting the importance of assessing early life disadvantages to understand suicidal ideation among immigrants. [ABSTRACT FROM AUTHOR]