Allergic symptoms in association with naturalness, greenness, and greyness: A cross-sectional study in schoolchildren in the Alps

Association of residential greenness with incident allergic rhinitis among adults: A prospective analysis of UK Biobank

BACKGROUND

Limited studies have assessed the impact of residential greenness exposure on allergic rhinitis in adults, and its relationship with ambient air pollutants remains unknown.

OBJECTIVE

To investigate the association of residential greenness with allergic rhinitis incidence and explore the mediation effects of ambient air pollutants in adults using data from a prospective cohort study in UK Biobank.

METHODS

Greenness was defined as the area-weighted mean of greenness coverage based on the land used data from the Generalized Land Use Database for England (GLUD) 2005 in the UK Biobank. Multiple Cox proportional hazard models and a generalized additive model incorporating restricted cubic splines were used to model the potential nonlinear effect of residential greenness on allergic rhinitis incidence and the potential mediation effect of ambient air pollutants.

RESULTS

Among the 281,699 subjects included in the analysis, 3260 allergic rhinitis incident cases occurred after a median follow-up of 14 years. With per 10% increase in residential greenness at a 300-m buffer, a 2.5% (95% CI: 1.0%, 4.0%) decreased risk of allergic rhinitis was observed. An L-shaped, non-linear dose-response relationship was indicated with a threshold of 54.9% greenness above which no excess allergic rhinitis risk was seen. PM10 partially mediated the relationship between greenness and allergic rhinitis incidence with a mediation effect of 26.9% (95% CI: 12.6%, 41.2%). A similar pattern of association was found at 1000-m buffer size.

CONCLUSION

This study demonstrates a significant beneficial effect of residential greenness on reducing allergic rhinitis incidence. Greenness may erase air pollutants and mitigate the rhinitis risk from air pollution.

Prenatal and postnatal early life exposure to greenness and particulate matter of different size fractions in relation to childhood rhinitis - A multi-center study in China

The impact of early life exposure to residential greenness on childhood rhinitis and its interaction with particulate matter (PM) of different size fractions remain inconsistent. Herein, we recruited 40,486 preschool children from randomly selected daycare centers in 7 cities in China from 2019 to 2020, and estimated exposure to residential greenness by the normalized difference vegetation index (NDVI) with a 500 m buffer. Exposure to ambient PM (PM1, PM2.5, and PM10) was evaluated using a satellite-based prediction model (daily, at a resolution of 1 km × 1 km). By mixed-effect logistic regression, NDVI values during pregnancy, in the first (0-1 year old) and the second (1-2 years old) year of life were negatively associated with lifetime rhinitis (LR) and current rhinitis (CR) (P < 0.001). PM in the same time windows was associated with increased risks of LR and CR in children, with smaller size fraction of PM showing greater associations. The negative associations between prenatal and postnatal NDVI and LR and CR in preschool children remained robust after adjusting for concomitant exposure to PM, whereas the associations of postnatal NDVI and rhinitis showed significant interactions with PM. At lower levels of PM, postnatal NDVI remained negatively associated with rhinitis and was partly mediated by PM (10.0-40.9 %), while at higher levels of PM, the negative associations disappeared or even turned positive. The cut-off levels of PM were identified for each size fraction of PM. In conclusion, prenatal exposure to greenness had robust impacts in lowering the risk of childhood rhinitis, while postnatal exposure to greenness depended on the co-exposure levels to PM. This study revealed the complex interplay of greenness and PM on rhinitis in children. The exposure time window in prenatal or postnatal period and postnatal concomitant PM levels played important roles in influencing the associations between greenness, PM and rhinitis.

Greenness and its composition and configuration in association with allergic rhinitis in preschool children

BACKGROUND

Few studies focus on the associations of green space composition and configuration with children's allergic rhinitis (AR).

METHODS

A multi-center population-based cross-sectional study was performed in 7 cities in mainland of China between 2019 and 2020, recruiting 36,867 preschool children. Information on the current AR symptoms and demographics were collected by questionnaire. Exposure to residential greenness was estimated by Normalized Difference Vegetation Index (NDVI, 1000 m buffer) around the residences. Greenness composition was estimated in 3 main categories: forest, grassland, shrubland. Configuration of each category and total greenness (a spatial resolution of 10 m × 10 m) was estimated by 6 landscape pattern metrics to quantify their area, shape complexity, aggregation, connectivity, and patch density. Exposure to daily ambient particulate matter (PM1, PM2.5 and PM10, a spatial resolution of 1 km × 1 km) was estimated. Multilevel logistic regression models were applied to analyze the associations of greenness and its composition and configuration with AR, and mediation effects by PMs were examined by mediation analysis models.

RESULTS

The prevalence of self-reported current AR in preschool children was 33.1%. Two indicators of forest, Aggregation Index of forest patches (AIforest) (odds ratio (OR):0.92, 95% Confidential Interval (CI): 0.88-0.97), and Patch Cohesion of forest (COHESIONforest) (OR: 0.93, 95% CI:0.89-0.98) showed significantly negative associations with AR symptoms. Mediation analyses found the associations were partially mediated by PMs. Age, exclusive breastfeed duration and season were the potential effect modifiers. The associations varied across seven cities.

CONCLUSION

Our findings suggest the inverse associations of the aggregation and connectivity of forest patches surrounding residence addresses with AR symptoms. Since the cross-sectional study only provides associations rather than causation, further studies are needed to confirm our results as well as the underlying mechanisms.

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.

Impact of socioeconomic factors on allergic diseases

Allergic and immunologic conditions, including asthma, food allergy, atopic dermatitis, and allergic rhinitis, are among the most common chronic conditions in children and adolescents that often last into adulthood. Although rare, inborn errors of immunity are life-altering and potentially fatal if unrecognized or untreated. Thus, allergic and immunologic conditions are both medical and public health issues that are profoundly affected by socioeconomic factors. Recently, studies have highlighted societal issues to evaluate factors at multiple levels that contribute to health inequities and the potential steps toward closing those gaps. Socioeconomic disparities can influence all aspects of care, including health care access and quality, diagnosis, management, education, and disease prevalence and outcomes. Ongoing research, engagement, and deliberate investment of resources by relevant stakeholders and advocacy approaches are needed to identify and address the impact of socioeconomics on health care disparities and outcomes among patients with allergic and immunologic diseases.

Greenness and chronic respiratory health issues: a systematic review and meta-analysis

Introduction

The number of chronic respiratory disease (CRD) individuals worldwide has been continuously increasing. Numerous studies have shown that greenness can improve chronic respiratory health issues through different mechanisms, with inconsistent evidence. By quantitatively summarizing existing studies, our purpose is to determine the connection between greenness exposure and various chronic respiratory health.

Methods

We conducted a comprehensive search on PubMed, EMBASE, and Web of Science core databases to identify relevant studies on the correlation between greenness exposure and chronic respiratory health issues. Studies published up to January 2023 were included in the search. The study used the most frequent indicator (normalized difference vegetation index [NDVI]) as the definition of greenness exposure.

Results

We finally identified 35 studies for meta-analysis. We calculated pooled effects across studies using a random-effects model and conducted a subgroup analysis by age and buffer zones to discuss the effects on chronic respiratory health issues. This study showed that 0.1 increments in NDVI were significantly related to lower rates of asthma incidence, lung cancer incidence, and chronic obstructive pulmonary disease (COPD) mortality risk; the pooled RRs were 0.92 (95% CI: 0.85-0.98), 0.62 (95% CI: 0.40-0.95), and 0.95 (95% CI: 0.92- 0.99), respectively. For the age subgroup, the higher greenness exposure level was related to the incidence rate of asthma among teenagers aged 13-18years (RR: 0.91; 95% CI: 0.83-0.99). For the buffer subgroup, a positive relationship with greenness exposure and asthma incidence/prevalence at 200-300m and 800- 1000m buffers, as well as the COPD mortality at 800-1000m buffer, the pooled RRs were 0.92 (95% CI: 0.86-0.98), 0.87 (95% CI: 0.81-0.93), and 0.93 (95% CI: 0.88- 0.98), respectively. Evidence of publication bias was not detected in this study.

Discussion

Our study is the first global meta-analysis between greenness and various CRDs to report an inverse association. Further research is needed in order to determine the effect of greenness exposure on different CRDs. Therefore, when planning for green development, more consideration must be given to public health and green management as intervention measures.

https://www.crd.york.ac.uk/PROSPEROFILES/384029_STRATEGY_20230116.pdf.

Villeneuve P, Kaiser DJ, Smargiassi A. The influence of urban trees and total vegetation on asthma development in children

Objective

We aimed to assess whether the influence of urban vegetation on asthma development in children (<13 years) varies by type (e.g., total vegetation, tree type, and grass) and season.

Methods

We used a cohort of all children born in Montreal, Canada, between 2000 and 2015. Children and cases were identified from linked medico-administrative databases. Exposure to residential vegetation was estimated using the Normalized Difference Vegetation Index (NDVI) for total vegetation and using the total area covered by deciduous and evergreen crowns for trees in 250 m buffers centered on residential postal codes. Seasonal variations in vegetation were modeled by setting values to zero on days outside of pollen and leaf-on seasons. Cox models with vegetation exposures, age as a time axis, and adjusted for sex, material deprivation, and health region were used to estimate hazard ratios (HR) for asthma development.

Results

We followed 352,946 children for a total of 1,732,064 person-years and identified 30,816 incident cases of asthma. While annual vegetation (total and trees) measures did not appear to be associated with asthma development, models for pollen and leaf-on seasons yielded significant nonlinear associations. The risk of developing asthma was lower in children exposed to high levels (>33,300 m2) of deciduous crown area for the leaf-on season (HR = 0.69; 95% confidence interval [CI] = 0.67, 0.72) and increased for the pollen season (HR = 1.07; 95% CI =1.02, 1.12), compared with unexposed children. Similar results were found with the Normalized Difference Vegetation Index.

Conclusion

The relationship between urban vegetation and childhood asthma development is nonlinear and influenced by vegetation characteristics, from protective during the leaf-on season to harmful during the pollen season.

The effect of greenness on allergic rhinitis outcomes in children and adolescents: A systematic review and meta-analysis

BACKGROUND

The relationship between greenness and health emerges as new public health concern. More published studies from multiple areas have explored the relationship between greenness and allergic rhinitis (AR) in children and adolescents. This study aims to determine the association between greenness and allergic rhinitis by systematic review and meta-analysis, in order to provide a more comprehensive assessment of the impact of greenness on AR in children and adolescents.

METHODS

The relative literature was systematically searched in PubMed, Embase, and Web of science lastly on September 25, 2022. Terms related to greenness and allergic rhinitis were used for searching. Summary effect estimates of greenness on AR in children and adolescents were calculated for per 10 % increase of greenness exposure with different buffer sizes by random-effects model.

RESULTS

A total of 579 studies were screened, and fourteen studies from Europe, Asia and North America were finally included. Most greenness exposure were measured by normalized difference vegetation index (NDVI). Enhanced vegetation index, outdoor-green environmental score and existed to measuring different greenness types. Greenness surrounding residences and schools were assessed. The overall effect of greenness on primary outcome was 1.00 (95%CI = 0.99-1.00). Most effect estimates of greenness were included in the NDVI-500 m group, and the pooled OR was 0.99 (95%CI = 0.97-1.01). No significant pooled estimates were found in analyses with study locations.

CONCLUSION

This study indicates no significant association between greenness exposure and AR in children and adolescents. Various exposure measures and conversion of data may affect the results of this meta-analysis. More precise assessment of personal greenness exposure in well-designed prospective studies are vital for drawing a definite association in future. Furthermore, greenness exposure surrounding schools should be paid considerable attention for its effect on AR in school-aged children and adolescents.

Environmental Exposures may Hold the Key; Impact of Air Pollution, Greenness, and Rural/Farm Lifestyle on Allergic Outcomes

PURPOSE OF REVIEW

There has been an increased prevalence of allergy. Due to this relatively rapid rise, changes in environmental exposures are likely the main contributor. In this review, we highlight literature from the last 3 years pertaining to the role of air pollution, greenness, and the rural/farm lifestyle and their association with the development of allergic sensitization, atopic dermatitis, food allergy, and allergic rhinitis in infancy and childhood. Because asthma has a more complex pathophysiology, it was excluded from this review.

RECENT FINDINGS

Recent studies support a role for air pollution, greenness, and rural/farming lifestyle influencing atopic outcomes that continue to be defined. While many studies have examined singular environmental exposures, the interconnectedness of these exposures and others points to a need for future work to consider an individual's whole exposure. Environmental exposures' influence on atopic disease development remains an ongoing and important area of study.

Association between exposure to greenness and atopic march in children and adults-A systematic review and meta-analysis

Introduction

Allergic diseases are a global public health problem. Food allergy, atopic dermatitis (AD), allergic rhinoconjunctivitis, allergic rhinitis (AR) and asthma represent the natural course of allergic diseases, also known as the "atopic march". In recent years, a large number of studies have been published on the association between greenness exposure and allergic diseases. However, systematic reviews on the association between greenness exposure and multiple allergic diseases or atopic march are lacking.

Methods

In this study, PubMed, EMBASE, ISI Web of Science, and Scopus were systematically searched. Meta-analyses were performed if at least three studies reported risk estimates for the same outcome and exposure measures.

Results

Of 2355 records, 48 studies were included for qualitative review. Five birth cohort studies, five cross-sectional studies, and one case-control study were included for asthma meta-analysis, respectively. Four birth cohort studies were included for AR meta-analysis. Our results support that exposure to a greener environment at birth reduces the risk of asthma and AR in childhood. In addition, higher greenness exposure was associated with decreased odds of current asthma in children.

Discussion

There was a large heterogeneity among the included studies and most of them did not specify the vegetation type and causative allergens. Therefore the study results need to be further validated. In addition, a small number of studies evaluated the association between greenness and food allergy, AD and allergic rhinoconjunctivitis. More research is needed to strengthen our understanding of the association between greenness and allergic diseases.

The PAD-US-AR dataset: Measuring accessible and recreational parks in the contiguous United States

Most spatial epidemiological studies of nature-health relationships use generalized greenspace measures. For instance, coarse-resolution spatial data containing normalized difference vegetative index (NDVI) values are prominent despite criticisms, such as the inability to restrain exposure estimates to public and private land. Non-threatening natural landscapes can improve health by building capacities for health-promoting behaviors. Recreational and accessible parks may best activate such behaviors. We curated the Parks and Protected Areas Database of the U.S. (PAD-US) to identify parks that are accessible for outdoor recreation. Our title adds "AR" to "PAD-US" where A = Accessible and R = Recreational. We validated the PAD-US-AR by comparisons with greenspace datasets and sociodemographics, which demonstrated its uniqueness from other commonly employed metrics of nature exposure. The PAD-US-AR presents reliable estimates of parks in the contiguous U.S. that are accessible for outdoor recreation. It has strong associations with home prices, shares of female residents, and shares of older residents. This dataset can accompany other nature exposure metrics in environmental epidemiology and allied research fields.

Association of individual green space exposure with the incidence of asthma and allergic rhinitis: a systematic review and meta-analysis

The association between allergic respiratory diseases, such as asthma and allergic rhinitis (AR), and green space (GS) remains controversial. Our study aimed to summarize and synthesize the association between individual GS exposure and the incidence of asthma/AR. We systematically summarized the qualitative relationship between GS exposure and asthma and AR. The pooled odds ratio (OR) with 95% confidence intervals (CIs) was used to estimate the effect of the Normalized Difference Vegetation Index (NDVI) on asthma and AR. A total of 21 studies were included for systematic review, and 8 of them underwent meta-analysis. In the meta-analysis of current asthma, the 0 < radius ≤ 100 m group, 100 < radius ≤ 300 m group, and 500 < radius ≤ 1000 m group presented weak negative associations between the NDVI and current asthma. For ever asthma, slight positive associations existed in the 0 < radius ≤ 100 m group and 300 < radius ≤ 500 m group. In addition, the NDVI might slightly reduce the risk of AR in radius of 100 m and 500 m. Our findings suggest that the effects of GS exposure on asthma and AR were not significant. Differences in GS measurements, disease diagnoses and adjusted confounders across studies may have an impact on the results. Subsequent studies should consider potential confounding factors and use more accurate GS exposure measurements to better understand the impact of GS exposure on respiratory disease in the population.

The associations between residential greenness and allergic diseases in Chinese toddlers: A birth cohort study

BACKGROUND

Green space in the living environment has been linked to the development of allergic diseases. However, evidence regarding early-onset allergy in toddlers was limited, and the critical exposure window remained unclear. We aimed to investigate associations between residential greenness with allergic diseases in early life.

METHODS

This prospective birth cohort study included 522 mother-child pairs in Guangzhou, China. We quantified prenatal, postnatal, and early-life (i.e., the first 1000 days of life) residential greenness, estimated from remote satellite data using normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and tree cover. We identified physician-diagnosed allergic diseases (eczema, atopic dermatitis, urticaria, allergic rhinitis, allergic conjunctivitis, food allergy, and asthma) based on medical records at age 2 years. Generalized linear regression was conducted to examine the associations of greenness with allergic outcomes.

RESULTS

The ranges of residential NDVI and EVI values in 500-m buffer during early life were 0.06-0.70 and 0.03-0.46, respectively. We found a 0.1 unit increase of NDVI in 500-m buffer throughout early life was associated with higher odds of any allergic diseases (prenatal: OR [odds ratio], 1.25; 95%CI, 1.02-1.53; postnatal: OR, 1.24; 95%CI, 1.02-1.52; early-life: OR, 1.25, 95%CI: 1.02-1.53) and higher odds of eczema (prenatal: OR, 1.28; 95%CI, 1.04-1.59; postnatal: OR, 1.24; 95%CI, 1.01-1.54; early-life: OR, 1.26, 95%CI: 1.02-1.56). The results were consistent when using EVI as a proxy for greenness. We only observed that prenatal exposure to the highest tertile of NDVI-500 was adversely associated with any allergic diseases (OR, 1.63; 95%CI, 1.03-2.58) and eczema (OR, 1.70; 95%CI: 1.04-2.78) compared with the lowest tertile.

CONCLUSIONS

This study identified detrimental associations of residential greenness with allergic diseases especially eczema among toddlers, and pregnancy appears to be the critical exposure window. Our findings highlighted the importance of urban planning to develop friendly-green neighborhood to improve maternal and child health.

Grassland allergenicity increases with urbanisation and plant invasions

Pollen allergies have been on the rise in cities, where anthropogenic disturbances, warmer climate and introduced species are shaping novel urban ecosystems. Yet, the allergenic potential of these urban ecosystems, in particular spontaneous vegetation outside parks and gardens, remains poorly known. We quantified the allergenic properties of 56 dry grasslands along a double gradient of urbanisation and plant invasion in Berlin (Germany). 30% of grassland species were classified as allergenic, most of them being natives. Urbanisation was associated with an increase in abundance and diversity of pollen allergens, mainly driven by an increase in allergenic non-native plants. While not inherently more allergenic than native plants, the pool of non-natives contributed a larger biochemical diversity of allergens and flowered later than natives, creating a broader potential spectrum of allergy. Managing novel risks to urban public health will involve not only targeted action on allergenic non-natives, but also policies at the habitat scale favouring plant community assembly of a diverse, low-allergenicity vegetation. Similar approaches could be easily replicated in other cities to provide a broad quantification and mapping of urban allergy risks and drivers.

Exposure to urban greenspace and pathways to respiratory health: An exploratory systematic review

BACKGROUND/OBJECTIVE

Urban greenspace may have a beneficial or adverse effect on respiratory health. Our objective was to perform an exploratory systematic review to synthesise the evidence and identify the potential causal pathways relating urban greenspace and respiratory health.

METHODS

We followed PRISMA guidelines on systematic reviews and searched five databases for eligible studies during 2000-2021. We incorporated a broad range of urban greenspace and respiratory health search terms, including both observational and experimental studies. Screening, data extraction, and risk of bias, assessed using the Navigation Guide criteria, were performed independently by two authors. We performed a narrative synthesis and discuss suggested pathways to respiratory health.

RESULTS

We identified 108 eligible papers (n = 104 observational, n = 4 experimental). The most common greenspace indicators were the overall greenery or vegetation (also known as greenness), green land use/land cover of physical area classes (e.g., parks, forests), and tree canopy cover. A wide range of respiratory health indicators were studied, with asthma prevalence being the most common. Two thirds (n = 195) of the associations in these studies were positive (i.e., beneficial) with health, with 31% (n = 91) statistically significant; only 9% (n = 25) of reported associations were negative (i.e., adverse) with health and statistically significant. The most consistent positive evidence was apparent for respiratory mortality. There were n = 35 (32%) 'probably low' and n = 73 (68%) 'probably high' overall ratings of bias. Hypothesised causal pathways for health benefits included lower air pollution, more physically active populations, and exposure to microbial diversity; suggested mechanisms with poorer health included exposure to pollen and other aeroallergens.

CONCLUSION

Many studies showed positive association between urban greenspace and respiratory health, especially lower respiratory mortality; this is suggestive, but not conclusive, of causal effects. Results underscore the importance of contextual factors, greenspace metric employed, and the potential bias of subtle selection factors, which should be explored further.

Does Living near Trees and Other Vegetation Affect the Contemporaneous Odds of Asthma Exacerbation among Pediatric Asthma Patients?

Vegetation may influence asthma exacerbation through effects on aeroallergens, localized climates, air pollution, or children's behaviors and stress levels. We investigated the association between residential vegetation and asthma exacerbation by conducting a matched case-control study based on electronic health records of asthma patients, from the Children's Hospital of Philadelphia (CHOP). Our study included 17,639 exacerbation case events and 34,681 controls selected from non-exacerbation clinical visits for asthma, matched to cases by age, sex, race/ethnicity, public payment source, and residential proximity to the CHOP main campus ED and hospital. Overall greenness, tree canopy, grass/shrub cover, and impervious surface were assessed near children's homes (250 m) using satellite imagery and high-resolution landcover data. We used generalized estimating equations to estimate odds ratios (OR) and 95% confidence intervals (CI) for associations between each vegetation/landcover measure and asthma exacerbation, with adjustment for seasonal and sociodemographic factors-for all cases, and for cases defined by diagnosis setting and exacerbation frequency. Lower odds of asthma exacerbation were observed in association with greater levels of tree canopy near the home, but only for children who experienced multiple exacerbations in a year (OR = 0.94 per 10.2% greater tree canopy coverage, 95% CI = 0.90-0.99). Our findings suggest possible protection for asthma patients from tree canopy, but differing results by case frequency suggest that potential benefits may be specific to certain subpopulations of asthmatic children.

Residential greenness, asthma, and lung function among children at high risk of allergic sensitization: a prospective cohort study

BACKGROUND

While benefits of greenness to health have been reported, findings specific to child respiratory health are inconsistent.

METHODS

We utilized a prospective birth cohort followed from birth to age 7 years (n = 617). Residential surrounding greenness was quantified via Normalized Difference Vegetation Index (NDVI) within 200, 400, and 800 m distances from geocoded home addresses at birth, age 7 years, and across childhood. Respiratory health outcomes were assessed at age 7 years, including asthma and lung function [percent predicted forced expiratory volume in the first second (%FEV₁), percent predicted forced vital capacity (%FVC), and percent predicted ratio of forced expiratory volume in the first second to forced vital capacity (%FEV₁/FVC)]. We assessed associations using linear and logistic regression models adjusted for community deprivation, household income, and traffic-related air pollution. We tested for effect measure modification by atopic status.

RESULTS

We noted evidence of positive confounding as inverse associations were attenuated upon adjustment in the multivariable models. We found evidence of effect measure modification of NDVI and asthma within 400 m at age 7 years by atopic status (p = 0.04), whereby children sensitized to common allergens were more likely to develop asthma as exposure to greenness increased (OR = 1.3, 95% CI: 0.9, 2.0) versus children not sensitized to common allergens (OR = 0.8, 95% CI: 0.5, 1.2). We found consistently positive associations between NDVI and %FEV₁ and %FVC which similarly evidenced positive confounding upon adjustment. In the adjusted regression models, NDVI at 7 years of age was associated with %FEV₁ (200 m: β = 2.1, 95% CI: 0.1, 3.3; 400 m: β = 1.6, 95% CI: 0.3, 2.9) and %FVC (200 m: β = 1.8, 95% CI: 0.7, 3.0; 400 m: β = 1.6, 95% CI: 0.3, 2.8; 800 m: β = 1.5, 95% CI: 0.1, 2.8). Adjusted results for %FEV₁/FVC were non-significant except exposure at birth in the 400 m buffer (β = 0.81, 95% CI: 0.1, 1.5). We found no evidence of effect measure modification of NDVI by atopic status for objective measures of lung function.

CONCLUSION

Sensitivity to allergens may modify the effect of greenness on risk for asthma in children but greenness is likely beneficial for concurrent lung function regardless of allergic status.

Nature and Children's Health: A Systematic Review

CONTEXT

Daily outdoor play is encouraged by the American Academy of Pediatrics. Existing evidence is unclear on the independent effect of nature exposures on child health.

OBJECTIVE

We systematically evaluated evidence regarding the relationship between nature contact and children's health.

DATA SOURCES

The database search was conducted by using PubMed, Cumulative Index to Nursing and Allied Health Literature, PsychInfo, ERIC, Scopus, and Web of Science in February 2021.

STUDY SELECTION

We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. In all searches, the first element included nature terms; the second included child health outcome terms.

DATA EXTRACTION

Of the 10 940 studies identified, 296 were included. Study quality and risk of bias were assessed.

RESULTS

The strongest evidence for type of nature exposure was residential green space studies (n = 147, 50%). The strongest evidence for the beneficial health effects of nature was for physical activity (n = 108, 32%) and cognitive, behavioral, or mental health (n = 85, 25%). Physical activity was objectively measured in 55% of studies, and 41% of the cognitive, behavioral, or mental health studies were experimental in design.

LIMITATIONS

Types of nature exposures and health outcomes and behaviors were heterogenous. Risk of selection bias was moderate to high for all studies. Most studies were cross-sectional (n = 204, 69%), limiting our ability to assess causality.

CONCLUSIONS

Current literature supports a positive relationship between nature contact and children's health, especially for physical activity and mental health, both public health priorities. The evidence supports pediatricians in advocating for equitable nature contact for children in places where they live, play, and learn.

The Role of Environmental Risk Factors on the Development of Childhood Allergic Rhinitis

Environmental factors play an important role in the development and exacerbation of allergic rhinitis (AR) in childhood. Indoor air pollution, such as house dust mites and secondhand smoke, can significantly increase the onset of AR, while pet dander may affect the exacerbation of AR symptoms in children. Furthermore, traffic related air pollution and pollen are outdoor air pollutants that can affect immune competency and airway responsiveness, increasing the risk of AR in children. Climate change has increased AR in children, as growth patterns of allergenic species have changed, resulting in longer pollen seasons. More extreme and frequent weather events also contribute to the deterioration of indoor air quality due to climate change. Additionally, viruses provoke respiratory tract infections, worsening the symptoms of AR, while viral infections alter the immune system. Although viruses and pollution influence development and exacerbation of AR, a variety of treatment and prevention options are available for AR patients. The protective influence of vegetation (greenness) is heavily associated with air pollution mitigation, relieving AR exacerbations, while the use of air filters can reduce allergic triggers. Oral antihistamines and intranasal corticosteroids are common pharmacotherapy for AR symptoms. In this review, we discuss the environmental risk factors for AR and summarize treatment strategies for preventing and managing AR in children.

Association between Green Space Structure and the Prevalence of Asthma: A Case Study of Toronto

Asthma is a chronic inflammatory disease that can be caused by various factors, such as asthma-related genes, lifestyle, and air pollution, and it can result in adverse impacts on asthmatics' mental health and quality of life. Hence, asthma issues have been widely studied, mainly from demographic, socioeconomic, and genetic perspectives. Although it is becoming increasingly clear that asthma is likely influenced by green spaces, the underlying mechanisms are still unclear and inconsistent. Moreover, green space influences the prevalence of asthma concurrently in multiple ways, but most existing studies have explored only one pathway or a partial pathway, rather than the multi-pathways. Compared to greenness (measured by Normalized Difference Vegetation Index, tree density, etc.), green space structure-which has the potential to impact the concentration of air pollution and microbial diversity-is still less investigated in studies on the influence of green space on asthma. Given this research gap, this research took Toronto, Canada, as a case study to explore the two pathways between green space structure and the prevalence of asthma based on controlling the related covariates. Using regression analysis, it was found that green space structure can protect those aged 0-19 years from a high risk of developing asthma, and this direct protective effect can be enhanced by high tree diversity. For adults, green space structure does not influence the prevalence of asthma unless moderated by tree diversity (a measurement of the richness and diversity of trees). However, this impact was not found in adult females. Moreover, the hypothesis that green space structure influences the prevalence of asthma by reducing air pollution was not confirmed in this study, which can be attributed to a variety of causes.

Green Space and Health Equity: A Systematic Review on the Potential of Green Space to Reduce Health Disparities

Disadvantaged groups worldwide, such as low-income and racially/ethnically minoritized people, experience worse health outcomes than more privileged groups, including wealthier and white people. Such health disparities are a major public health issue in several countries around the world. In this systematic review, we examine whether green space shows stronger associations with physical health for disadvantaged groups than for privileged groups. We hypothesize that disadvantaged groups have stronger protective effects from green space because of their greater dependency on proximate green space, as they tend to lack access to other health-promoting resources. We use the preferred reporting items for systematic reviews and meta-analyses (PRISMA) method and search five databases (CINAHL, Cochrane, PubMed, Scopus, and Web of Science) to look for articles that examine whether socioeconomic status (SES) or race/ethnicity modify the green space-health associations. Based on this search, we identify 90 articles meeting our inclusion criteria. We find lower-SES people show more beneficial effects than affluent people, particularly when concerning public green spaces/parks rather than green land covers/greenness. Studies in Europe show stronger protective effects for lower-SES people versus higher-SES people than do studies in North America. We find no notable differences in the protective effects of green space between racial/ethnic groups. Collectively, these results suggest green space might be a tool to advance health equity and provide ways forward for urban planners, parks managers, and public health professionals to address health disparities.