Association between the concentration and the elemental composition of outdoor PM2. 5 and respiratory diseases in schoolchildren : a multicenter study in the Mediterranean area

Asthma is a worldwide health problem and its prevalence has been increasing in many countries, especially in young children [1]. Asthma prevalence is particularly high in industrialized countries, even though a change in trend was noticed in the most recent years [2]. Multiple genetic factors increase the risk of developing asthma, whilst environmental conditions play a fundamental role in the expression of its symptoms [3]. In fact, the avoidance of air pollution has been suggested as a nonpharmacological intervention for the prevention of asthma exacerbations in the latest Global Initiative for Asthma (GINA) Guidelines [1]. Exposure to outdoor air pollution increases asthma symptoms, and asthmatic children are at increased risk of adverse effects from poor air quality [4,5]. The World Health Organization (WHO) stated that a high level of outdoor pollutant concentration is a determinant of worsening asthma symptoms in both children and adults [6]. In particular, high airborne particulate matter (PM) concentration has been associated with worsening of symptoms, especially in sensitive children [7], and the prevalence of allergic respiratory diseases is higher in urban areas and still on the rise [8]. Children vulnerability to atmospheric pollution was attributed to their high breath rate and to both physiological and anatomical immaturity [9]. A number of studies have demonstrated an association between respiratory symptoms, the diagnosis of asthma, and proximity of residences to industrial settlements such as oil refineries, petrochemical plants [10–12], and power plants [13,14]. Thus, living in urban environments or in proximity to industrial complexes may worsen respiratory health in children. The aim of the study was to assess the potential role of residing in different areas which had varying levels of pollution on current allergic respiratory diseases in schoolchildren. Thus, by means of a multicenter cross-sectional study, we evaluated children living in areas close to petrochemical and power plants in a ...