School environment associates with lung function and autonomic nervous system activity in children: a cross-sectional study

Abstract

Children are in contact with local environments, which may affect respiratory symptoms and allergic sensitization. We aimed to assess the effect of the environment and the walkability surrounding schools on lung function, airway inflammation and autonomic nervous system activity. Data on 701 children from 20 primary schools were analysed. Lung function, airway inflammation and pH from exhaled breath condensate were measured. Pupillometry was performed to evaluate autonomic activity. Land use composition and walkability index were quantified within a 500 m buffer zone around schools. The proportion of effects explained by the school environment was measured by mixed-effect models. We found that green school areas tended to be associated with higher lung volumes (FVC, FEV1 and FEF25–75%) compared with built areas. FVC was significantly lower in-built than in green areas. After adjustment, the school environment explained 23%, 34% and 99.9% of the school effect on FVC, FEV1, and FEF25–75%, respectively. The walkability of school neighbourhoods was negatively associated with both pupil constriction amplitude and redilatation time, explaining −16% to 18% of parasympathetic and 8% to 29% of sympathetic activity. Our findings suggest that the environment surrounding schools has an effect on the lung function of its students. This effect may be partially mediated by the autonomic nervous system.

The neighbourhood natural environment is associated with asthma in children: A birth cohort study

“…A possible reason for these contradicting results may derive from the fact that these studies only took into account availability/accessibility to green space, disregarding the richness of species in these areas. Some of the reported protective effects of green environments may actually be associated with the autonomic nervous system changes attributed to the contact with nature rather than a higher biodiversity, leading to stress reduction, lower heart rate and lower allostatic load in individuals living in those areas 12,17 . In other words, larger green areas do not necessarily hold higher number of species, and, in fact, even small green spaces can hold a significant amount of species richness depending on their habitat quality 18 .…”

Association between the density and type of trees around urban schools and exhaled nitric oxide levels in schoolchildren

“…has been previously considered by Paciência et al (9) since it is considered a reasonable walking distance for children as described by Brownson et al (30).…”

“…Both early-and late-life exposures to greenness were reported to be protective factors of asthma (11). We recently showed that schools´ neighborhoods may have an effect on lung function, as green areas around schools tended to be associated with improved lung function in schoolchildren, being linked with higher lung volumes comparatively with built areas (9). Furthermore, Cavaleiro Rufo et al (16) found a positive association between the exposure to species richness in schools and lung function, independently of the asthma and atopic status.…”

“…Several recent studies have shown that exposure to greenness may also be protective of asthma and allergic diseases (9)(10)(11)(12). Ruokolainen et al (10) found an inverse association between higher forest and agricultural land within 2 to 5 km around children and adolescents' homes and the risk of atopic sensitization.…”

“…The underlying mechanisms associated with exposure to green areas and asthma and allergic diseases are not well understood. However, accumulating data suggested that biodiversity and air pollution may be associated with human microbiota composition, changes in autonomic nervous system, airway inflammation and, consequently influence the development of asthma and allergic diseases (9,15,17).…”