Exposure to airborne fine particulate matter (PM_2.5) carries substantial health risks, particularly for younger children (0–10 years). Epidemiological evidence indicates that children are more susceptible to PM health effects than adults. We conducted a literature review to obtain an overview of existing knowledge regarding the correlation of exposure to short- and long-term PM concentrations with respiratory symptoms and disease in children. A collection of scientific papers and topical reviews were selected in cooperation with two experienced paediatricians. The literature review was performed using the keywords “air pollution”, “particulate matter”, “children’s health” and “respiratory” from 1950 to 2016, searching the databases of Scopus, Google Scholar, Web of Science, and PubMed. The search provided 45,191 studies for consideration. Following the application of eligibility criteria and experts’ best judgment to titles and abstracts, 28 independent studies were deemed relevant for further detailed review and knowledge extraction. The results showed that most studies focused mainly on the effect of short-term exposure in children, and the reported associations were relatively homogeneous amongst the studies. Most of the respiratory diseases observed in outdoor studies were related to changes in lung function and exacerbation of asthma symptoms. Allergic reactions were frequently reported in indoor studies. Asthma exacerbation, severe respiratory symptoms and moderate airway obstruction on spirometry were also observed in children due to various sources of indoor pollution in households and schools. Mixed indoor and outdoor studies indicate frequent occurrence of wheezing and deterioration of lung function. There is good evidence of the adverse effect of short-term exposure to PM on children’s respiratory health. In terms of long-term exposure, fine particles (PM_0.1–PM_2.5) represent a higher risk factor than coarse particles (PM_2.5–PM₁₀). Additional research is required to better understand the heterogeneous sources and the association of PM and adverse children’s health outcomes. We recommend long-term cooperation between air quality specialists, paediatricians, epidemiologists, and parents in order to improve the knowledge of PM effects on young children’s respiratory health.

The aim of this study was to link the concentrations of particulate matter with an aerodynamic diameter below 2.5 μm (PM_2.5) and associated heavy metals with occurrence of wheezing and hospitalizations due to wheezing in 111 children who live near metallurgical plants in Targoviste City, Romania. A group of 72 children with high levels of immunoglobulin E (IgE) and eosinophils, as well as frequent wheezing episodes, was geolocated on digital thematic maps. Monitoring campaigns and medical assessments were performed over two consecutive years (2013–2014). The multiannual average concentrations of PM_2.5 ranged from 4.6 to 22.5 μg m⁻³, up to a maximum value of 102 μg m⁻³. Significant correlations (p < 0.01) were observed between the locations of the children with respiratory issues and the PM_2.5 multiannual average (r = 0.985) and PM_2.5 maximum (r = 0.813). Fe, Ni, Cd, and Cr were the main marker elements of the emissions from steel production and metal-working facilities in the Targoviste area. The results support the hypothesis that increased PM_2.5 levels directly influence wheezing symptom and asthma attacks in the analyzed group. IgE, eosinophils, and wheezing episodes may be considered key indicators with which to evaluate the adverse effects of PM_2.5 air pollution on children’s health.

The overall objective of this research was to study children’s respiratory illness levels in Targoviste (Romania) in relationship to the outdoor concentrations of airborne particulate matter with an aerodynamic diameter below 2.5 µm (PM_2.5). We monitored and analysed the PM_2.5 concentrations according to a complex experimental protocol. The health trial was conducted over three months (October–December 2015) and required the active cooperation of the children’s parents to monitor carefully the respiratory symptoms of the child, i.e., coughing, rhinorrhoea, wheezing, and fever, as well as their outdoor program. We selected the most sensitive children (n = 25; age: 2–10 years) with perturbed respiratory health, i.e., wheezing, asthma, and associated symptoms. The estimated average PM_2.5 doses were 0.8–14.5 µg·day⁻¹ for weekdays, and 0.4–6.6 µg·day⁻¹ for the weekend. The frequency and duration of the symptoms decreased with increasing age. The 4- to 5-year old children recorded the longest duration of symptoms, except for rhinorrhoea, which suggested that this age interval is the most vulnerable to exogenous trigger agents (p < 0.01) compared to the other age groups. PM_2.5 air pollution was found to have a direct positive correlation with the number of wheezing episodes (r = 0.87; p < 0.01) in November 2015. Monitoring of wheezing occurrences in the absence of fever can provide a reliable assessment of the air pollution effect on the exacerbation of asthma and respiratory disorders in sensitive children.

This study aims to analyze the performances and correlation of the standardized precipitation index (SPI) and standardized precipitation evaporation index (SPEI) from the perspective of supplying effective indicators for drought risk management prevention. Indices have been evaluated using long time series of precipitation and temperature data (from 1961 to 2020) gauged and validated in the land monitoring system of the Umbria region (central Italy). Results show how SPEI can evaluate better the drought phenomena, both in terms of occurred events and in terms of trends. In particular, SPEI can appreciate the effects of the increase in temperatures, which in the next years could be predominant in c limate change. Currently, the high correlation between SPEI and SPI (R² > 0.8 and r > 0.9) makes possible the use of SPI instead of SPEI in drought analysis; however, this correlation, evaluated on the two times series 1961–1990 and 1991–2020, shows a decreasing tendency; then, it could be no longer reliable in the future. These results should lead to increasingly synergistic monitoring of rainfall and temperature data, limiting as much as possible the lack of temporal overlap of the two sensors at the gauging stations. The possibility of using ERA 5 reanalysis data was also explored for the years that presented severe droughts by comparing them to the station-based observations. While the temperature data is reliable, the total precipitation parameter seems less affordable, and then, other available gridded datasets, e.g., CHIRPS, MERRA2, and Terraclimate, should have to be considered to improve the modeled precipitation’s suitability. Graphical abstract