A variety of benefits of greenspace exposure on human health are well documented. Lacking in the literature, however, are studies focusing on possible associations between greenspace exposure and early markers of aging. This study adds to the literature by investigating the association between telomere length (TL) in young children. A telomere is a specialized cellular structure considered to be a marker of aging. The shortening of telomeres has been associated with a higher risk of developing different adverse health outcomes.
Two hundred children (age 5-7) from 27 kindergartens in Sabzevar, Iran participated in this study. All of the participants were considered to be healthy children who did not regularly use supplements or drugs, had no genetic health issues, were in kindergarten for at least one year, and lived in the same home since birth. Blood samples from each child were analyzed for leukocyte telomere length (LTL). Greenspace exposure for each child was based on four different measures: (1) home and kindergarten distance from green spaces; (2) surrounding greenspace at residential and kindergarten address; (3) time spent in private and public green spaces; and (4) the number of plant pots at home. Distance was calculated based on a land use map of the study area prepared by the municipality of Sabzevar. Surrounding greenness in buffers of 100m, 300m and 500m around home and school was based on satellite-derived Normalized Difference Vegetation Index (NDVI), a commonly used numerical indicator of greenspace. Questionnaires completed by parents provided information on time spent in green spaces and number of plant pots at home.
Results showed positive links between TL and more surrounding greenspace – for home at 300m buffer, for kindergarten at 300m and 500m buffers, and a combination of these two. Results also showed positive links between TL and less distance (from home or kindergarten) to green spaces larger than 5000m and longer time spent in public green spaces. There were no associations found between TL and (a) the residential and kindergarten surrounding greenspace in other buffers, (b) distance to any green space (other than the large green spaces), and (c) the number of plant pots at home. Results suggested stronger associations (though not statistically significant) for girls than boys and for children with parents having higher educational levels and living in neighborhoods with lower percentage of unemployment. These patterns were not consistent, however, for all indicators of greenspace exposure. Data generally suggest stronger associations for measures of surrounding greenspace in larger buffer sizes, which previous research would suggest might be related to opportunity for physical activity and air pollution mitigation. Indeed, results also showed that about one-third of the links between total surrounding greenspace and LTL could be explained by less exposure to air pollution.
These findings suggest a positive association between greenspace exposure and LTL in young children. Further research is warranted to see if similar results are found in other settings with different climates and populations.
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