Association between greenspace and lung function in Italian children-adolescents

Different greenness exposure in Europe and respiratory outcomes in youths. A systematic review and meta-analysis

The existing evidence on the association between greenness and respiratory outcomes remains inconclusive. We aimed at systematically summarizing existing literature on greenness exposure and respiratory outcomes in European children and adolescents, with a preliminary attempt to qualify the distribution of dominant tree species across different geographical areas and bioclimatic regions. Overall, 4049 studies were firstly identified by searching PubMed/MEDLINE, EMBASE, Scopus, Web of Science, GreenFile and CAB direct, up to 29 August 2023. Eighteen primary studies were included in the systematic review and six were meta-analyzed. No overall significant association was observed between the Normalized Difference Vegetation Index, assessed within 500-m buffers (i.e. NDVI-500), and the odds of asthma for 0.3-increase in the exposure (OR: 0.97, 95% CI from 0.53 to 1.78). Similarly, an overall exposure to the NDVI-300 highest tertile, as compared to the lowest tertile, was not significantly associated with asthma (OR: 0.65, 95% CI from 0.22 to 1.91): heterogeneity among studies was significant (p = 0.021). We delineated some key elements that might have mostly contributed to the lack of scientific consensus on this topic, starting from the urgent need of harmonized approaches for the operational definition of greenness. Additionally, the complex interplay between greenness and respiratory health may vary across different geographical regions and climatic conditions. At last, the inconsistent findings may reflect the heterogeneity and complexity of this relationship, rather than a lack of scientific consensus itself. Future research should compare geographical areas with similar bioclimatic parameters and dominant or potentially present vegetation species, in order to achieve a higher inter-study comparability.

Residential surrounding greenness is associated with improved lung function in adults: a cross-sectional study in eastern China

BACKGROUND

While benefits of greenness exposure to health have been reported, findings specific to lung function are inconsistent. The purpose of this study is to assess the correlations of greenness exposure with multiple lung function indicators based on chronic obstructive pulmonary disease (COPD) monitoring database from multiple cities of Anhui province in China.

METHODS

We assessed the greenness using the annual average of normalized difference vegetation index (NDVI) with a distance of 1000-meter buffer around each local community or village. Three types of lung function indicators were considered, namely indicators of obstructive ventilatory dysfunction (FVC, FEV₁, FEV₁/FVC, and FEV₁/FEV₃); an indicator of large-airway dysfunction (PEF); indicators of small-airway dysfunction (FEF_25%, FEF_50%, FEF_75%, MMEF, FEV₃, FEV₆, and FEV₃/FVC). Linear mixed effects model was used to analyze associations of greenness exposure with lung function through adjusting age, sex, educational level, occupation, residence, smoking status, history of tuberculosis, family history of lung disease, indoor air pollution, occupational exposure, PM_2.5, and body mass index.

RESULTS

A total of 2768 participants were recruited for the investigations. An interquartile range (IQR) increase in NDVI was associated with better FVC (153.33mL, 95%CI: 44.07mL, 262.59mL), FEV₁ (109.09mL, 95%CI: 30.31mL, 187.88mL), FEV₃ (138.04mL, 95%CI: 39.43mL, 236.65mL), FEV₆ (145.42mL, 95%CI: 42.36mL, 248.47mL). However, there were no significant associations with PEF, FEF_25%, FEF_50%, FEF_75%, MMEF, FEV₁/FVC, FEV₁/FEV₆, FEV₃/FVC. The stratified analysis displayed that an IQR increase in NDVI was related with improved lung function in less than 60 years, females, urban populations, nonsmokers, areas with medium concentrations of PM_2.5 and individuals with BMI of less than 28 kg/m². Sensitivity analyses based on another greenness indice (enhanced vegetation index, EVI) and annual maximum of NDVI remained consistent with the main analysis.

CONCLUSIONS

Our findings supported that exposure to greenness was strongly related with improved lung function.

Greenspace and children's lung function in China: A cross-sectional study between 2013 and 2015

This study aims to investigate how surrounding greenspace density and proximity were associated with children's lung function. Between 2013 and 2015, spirometry and a parental survey were performed with children from four primary schools in two Chinese cities. Forced expiratory volume in 1 s (FEV₁, L), forced vital capacity (FVC, L), peak expiratory flow rate (PEF, L/s), and forced expiratory flow at 25 % (FEF₂₅, L/s) and 75 % (FEF₇₅, L/s) of FVC were measured. Outdoor surrounding greenspace index incorporated residential, school and commuting greenness and was weighted using assumed daytime hours spent at home and school. Residential proximity to greenspace index was defined as walking distance to nearest park. A total of 913 children (48.7 % female) were included. Overall, an interquartile range (IQR) increase in outdoor surrounding greenspace was associated with decreased FVC (0.06 L, 95%CI 0.01-0.11), but increased FEV₁/FVC (2.03, 1.13-3.04), PEF (0.26 L/s, 0.13-0.39), and FEF₂₅ (0.30 L/s, 0.17-0.42). Residential proximity to greenspace was associated with increased FEV₁ (0.05 L, 0.02-0.08) and FVC (0.04 L, 0.01-0.07) per IQR decrease in distance. Protective effect was significant for children whose parents were less educated and those living in higher road density areas, though interactions were not significant. Structural equation modeling showed that higher level of surrounding greenspace was associated with lower ambient air pollution and in turn with better lung function. Greenspace density and proximity could influence children's lung function differently.

Greenspace and health outcomes in children and adolescents: A systematic review

An increasing body of evidence has linked greenspace and various health outcomes in children and adolescents, but the conclusions were inconsistent. For this review, we comprehensively summarized the measurement methods of greenspace, resultant health outcomes, and potential mechanisms from epidemiological studies in children and adolescents (aged ≤19 years). We searched for studies published and indexed in MEDLINE and EMBASE (via Ovid) up to April 11, 2022. There were a total of 9,291 studies identified with 140 articles from 28 countries finally assessed and included in this systematic review. Over 70% of the studies were conducted in highly urbanised countries/regions, but very limited research has been done in low-and middle-income countries and none in Africa. Measures of greenspace varied. Various health outcomes were reported, including protective effects of greenspace exposure on aspects of obesity/overweight, myopia, lung health, circulatory health, cognitive function, and general health in children and adolescents. The associations between greenspace exposure and other health outcomes were inconsistent, especially for respiratory health studies. We pooled odds ratios (OR) using random-effects meta-analysis for health outcomes of asthma (OR = 0.94, 95%CI: 0.84 to 1.06), allergic rhinitis (OR = 0.95; 95% CI: 0.73 to 1.25), and obesity/overweight (OR = 0.91, 95%CI: 0.84 to 0.98) with per 0.1 unit increase in normalized difference in vegetation index (NDVI). These associations have important implications for the assessment and management of urban environment and health in children and adolescents.