Complex interplay between greenness and air pollution in respiratory health

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.

The exposome in respiratory diseases: multiple preventable risk factors from early life to adulthood

The increasing global burden of respiratory diseases over the last decades raises questions about the impact of environmental factors during industrialisation and urbanisation. Although the knowledge of environmental epidemiology is growing, it is still unclear what the most critical exposure windows are for respiratory health. In addition, the relationships between different environmental exposures can be complex. The exposome approach investigating all non-genetic factors on health has been developed in recent years but has been little applied in respiratory health to date. This journal club article reviews three recent publications investigating the effects of environmental exposures, considered separately or in an exposome approach with different exposure windows, on respiratory health outcomes. These three studies highlight targets for action in primary and secondary prevention. Two studies, using data from the INMA and RHINESSA cohorts, support the regulation and reduction of phthalates and air pollution, respectively. Moreover, the exposome approach conducted in the NutriNet-Santé cohort emphasises that risk reduction must involve a multi-interventional approach targeting both specific early-life risk factors and promotion of a healthy lifestyle in adulthood. These three articles also present research perspectives in environmental epidemiology.

Short-term PM1 and PM2.5 exposure and asthma mortality in Jiangsu Province, China: What's the role of neighborhood characteristics?

BACKGROUND

Evidence suggests that particulate matter (PM) with smaller particle sizes (such as PM₁, PM with an aerodynamic diameter≤1 µm) may have more toxic health effects. However, the short-term association between PM₁ and asthma mortality remains largely unknown.

OBJECTIVE

This study aimed to examine the short-term effects of PM₁ and PM_2.5 on asthma mortality, as well as to investigate how neighborhood characteristics modified this association.

METHODS

Daily data on asthma mortality were collected from 13 cities in Jiangsu Province, China, between 2016 and 2017. A time-stratified case-crossover design was attempted to examine the short-term effects of PM₁ and PM_2.5 on asthma mortality. Individual exposure levels of PM₁ and PM_2.5 on case and control days were determined based on individual's residential addresses. Stratified analyses by neighborhood characteristics (including green space, tree canopy, blue space, population density, nighttime light and street connectivity) were conducted to identify vulnerable living environments.

RESULTS

Mean daily concentrations of PM₁ and PM_2.5 on case days were 33.8 μg/m³ and 54.3 μg/m³. Each 10 μg/m³ increase in three-day-averaged (lag02) PM₁ and PM_2.5 concentrations were associated with an increase of 6.66% (95%CI:1.18%,12.44%) and 2.39% (95%CI: 0.05%-4.78%) asthma mortality, respectively. Concentration-response curves showed a consistent increase in daily asthma mortality with increasing PM₁ and PM_2.5 concentrations. Subgroup analyses indicated that the effect of PM₁ appeared to be evident in neighborhood characteristics with high green space, low urbanization level and poor street connectivity.

CONCLUSION

This study suggested an association between short-term PM₁ and PM_2.5 exposures and asthma mortality. Several neighborhood characteristics (such as green space and physical supportive environment) that could modify the effect of PM₁ on asthma mortality should be further explored.