Valeria Campos

This study estimated the relative risks (RRs) of respiratory and cardiovascular mortality and morbidity due to short-term ozone exposure in 13 polluted communes across Chile’s Santiago Metropolitan and Valparaíso regions. Data on daily ozone, meteorology, and pollutants were sourced from the National Air Quality Information System (NAQIS), while health outcomes (mortality, hospital admissions, and emergency visits) were obtained from the Department of Health Statistics. A Poisson regression model, adjusted for trends, meteorology, day-of-week effects, and pollutants, quantified RRs for a 10 ppb ozone increase, ranging from 1.004 to 1.198 (95% CI). The highest risks were in Santiago’s Eastern zone (cerebrovascular, RR 1.171, 95% CI: 1.018–1.347), Western zone (cardiovascular, RR 1.198, 95% CI: 1.049–1.369), and Valparaíso’s Viña del Mar (ischemic heart disease, RR 1.127, 95% CI: 1.017–1.248). The 5–64-year age group was most affected, particularly in terms of emergency visits. Reducing ozone to the WHO guideline (100 µg/m³) could avoid 837,498 cases in Santiago and 17,992 in Valparaíso annually, resulting in economic savings of $7,439,930,640 and $1,044,568,800, respectively. These results highlight the need for stricter air quality policies to reduce ozone-related health burdens.

The 2023–2024 blackouts in Quito, Ecuador, led to severe air quality deterioration, primarily driven by diesel generator use and increased vehicular traffic. This study analyzed data from seven urban and peri-urban monitoring stations, applying meteorologically normalized data and machine learning models (Boosted Regression Trees and Random Forests) to isolate the direct impact of blackouts on pollutant concentrations. The results revealed that PM₁₀ increased by up to 45% and PM_2.5 by 30%, frequently exceeding regulatory limits, particularly in industrial and residential zones. SO₂ exhibited the most extreme rise, surging by 390%, with peak values reaching 500 µg/m³ in areas heavily reliant on high-sulfur diesel generators. The NO₂ concentrations exceeded 200 µg/m³ in high-traffic areas, while O₃ showed dual behavior, decreasing in urban cores due to titration effects but increasing by 15% in suburban valleys, driven by photochemical interactions. A comparison between 2023 and 2024 blackouts highlighted worsening pollution trends, with longer (8–12 h) outages in 2024 causing severe environmental impacts. The findings demonstrate that blackouts significantly worsen air quality, posing critical public health risks. This study underscores the urgent need for policy interventions to mitigate the environmental impact of energy disruptions. Key recommendations include stricter fuel quality standards, diesel generator emission controls, and an accelerated transition to renewable energy. These results provide scientific evidence for future environmental regulations, supporting sustainable air quality management strategies to minimize future energy crises’ health and ecological consequences.

Tropospheric ozone is generated by photochemical reactions by precursor pollutants, or it can also proceed from stratospheric intrusion. In addition to affecting the population's health, ozone exposure threatens biodiversity conservation and the production of food and forest products.A prior study by this research group assessed public ozone monitoring stations across Chile, revealing that only stations near the Andes Mountains in central Chile exceed the national standard of 61 ppb. The highest concentrations were observed at Las Condes station (790 m.a.s.l.) and Los Andes station (830 m.a.s.l.).In this context, the present study aimed to determine whether tropospheric ozone exists in high concentrations in the Andes Mountains range at higher altitudes and its behavior. For this reason, an ozone monitoring station was installed at the NUNATAK-1 refuge laboratory, located in Portillo (32.844ºS, 70.129ºW), east of the Los Andes station, at 3,000 m.a.s.l. The monitoring period for this study spanned from October 6, 2022, to October 18, 2023, with minute resolution using Thermo Scientific™ 49iQ Ozone Monitor, which employs a dual cell UV photometry (sample and reference) to measure the amount of ozone in the air from ppb levels up to 200 ppm, (detection limit: 0.50 ppb in 60 second averaging time; precision: ±1.0 ppb; response time: 20 seconds).During the monitoring period, hourly averages of up to 80 ppb were observed, and the 99th percentile of the maximum daily 8-hour moving average was 61.56 ppb, exceeding the Chilean standard. The Portillo records were compared with Chile's most contaminated monitoring stations, Las Condes and Los Andes, using an ANOVA test, and a p-value ≤ 0.05 was obtained. Therefore, it is concluded that there are statistically significant differences between the stations. The LSD test further determined that Portillo exhibited a significantly higher average ozone concentration, with levels averaging 55% higher than those in Los Andes and 58% higher than those in Las Condes.In the northern hemisphere, elevated tropospheric ozone levels have been observed in high-altitude regions, including the western US, western Europe, central Japan, central China, Himalayas, Greenland, southern Algeria, and Izaña. However, in the southern hemisphere, ozone in mountainous areas has not been studied as extensively due to poor data coverage. This study unveils ozone records spanning a year in the Andes Mountains, revealing even higher concentrations than those observed in urban areas in Chile. Therefore, tropospheric ozone could be harming the biodiversity of the Andes Mountain range in central Chile. Furthermore, ozone could adversely affect the health of climbers and hikers exploring the Andes Mountain range.Subsequent studies should determine whether the tropospheric ozone recorded in the Andes Mountains range results from long-distance ozone or precursor pollutants transport from urban source regions, or ozone intrusion from the stratosphere. Photochemical modeling is recommended for a more comprehensive understanding and monitoring campaigns of the vertical ozone profile using radiosonde.Acknowledgment to ANID Project: Anillo ACONCAGUA ACT210021, Fondecyt Regular 1221526, FOVI230167, and ANID National PhD Scholarship 21202033.

Mercury is a toxic pollutant that can negatively impact the population’s health and the environment. The research on atmospheric mercury is of critical concern because of the diverse process that this pollutant suffers in the atmosphere as well as its deposition capacity, which can provoke diverse health issues. The Minamata Convention encourages the protection of the adverse effects of mercury, where research is a part of the strategies and atmospheric modelling plays a critical role in achieving the proposed aim. This paper reviews the study of modelling atmospheric mercury based on the southern hemisphere (SH). The article discusses diverse aspects focused on the SH such as the spatial distribution of mercury, its emissions projections, interhemispheric transport, and deposition. There has been a discrepancy between the observed and the simulated values, especially concerning the seasonality of gaseous elemental mercury and total gaseous mercury. Further, there is a lack of research about the emissions projections in the SH and mercury deposition, which generates uncertainty regarding future global scenarios. More studies on atmospheric mercury behaviour are imperative to better understand the SH’s mercury cycle.

The effect of magnesium chloride as an additive of hydrothermal carbonization (HTC) of lignocellulosic biomass (Pinus radiata sawdust) was studied. The HTC tests were carried out at fixed conditions of temperature and residence time of 220 °C and 1 h, respectively, and varying the dose of magnesium chloride in the range 0.0–1.0 g MgCl₂/g biomass. The carbonized product (hydrochar) was tested in order to determine its calorific value (HHV) while using PARR 6100 calorimeter, mass yield by gravimetry, elemental analysis using a LECO TruSpec elemental analyzer, volatile matter content, and ash content were obtained by standardized procedures using suitable ovens for it. The results show that using a dose of 0.75 g MgCl₂/g biomass results in an impact on the mass yield that was almost equal to change operating conditions from 220 to 270 °C and from 0.5 to 1 h, without additive. Likewise, the calorific value increases by 33% for this additive dose, resulting in an energy yield of 68%, thus generating a solid fuel of prominent characteristics.