Green Spaces May Mitigate Pollution-Linked Breast Cancer Risk

Green spaces, whether in the comfort of the home or within the heart of a bustling urban landscape, have benefits for people’s health and wellbeing. Emerging evidence suggests that there is a relationship between urban greenness and air pollution, where the latter can have negative effects on people’s health, such as accelerated aging and increased cancer risk.

Previous research by Carmen Smotherman, an epidemiologist at the University of Florida, identified a link between air pollution and the risk of postmenopausal breast cancer.¹ Driven by a desire to further explore how air pollution interacts with greenness in relation to this cancer risk, she and her colleagues utilized UK Biobank data from over 155,000 postmenopausal women in a new study.

The findings, recently published in PLOS One, revealed that green environments may reduce the impact of air pollution on breast cancer risk.² Through further investigation of these various environmental exposures, the researchers hope these insights can help inform urban planning to maximize potential health benefits.

Using the UK Biobank data, the researchers assessed the association among greenness, or normalized difference vegetation index (NDVI), cumulative air pollution, and breast cancer risk ratios. A higher NDVI value indicated denser vegetation, while a lower value indicated more barren areas. For air pollution, the researchers looked at pollutants with particulate matter sized less than 10 micrometers in diameter (PM10, which includes dust, pollen, and mold) from annual averages during 2007 and the cumulative averages from 2007 and 2010.

From their analysis, the team found that NDVI was positively associated with postmenopausal breast cancer risk: For each 0.1 unit increase in NDVI, there was a 2.6 percent increase in risk. This association has been found in some but not all other studies. The researchers acknowledged that this inconsistency may be due to how scientists measure greenness, whether it is the percentage of greenspace and natural environment, the index value, or even the area of greenness around an individual’s home address.

However, when looking at the relationship between greenness and air pollution, the team found that the association between the cumulative average PM10 and breast cancer risk was stronger in women who lived in areas with lower NDVI levels, compared to those who lived in greener spaces. These findings suggest that greenness may affect air pollution exposure, by reducing the level of pollutants, and consequently decreasing breast cancer risk.

Based on these findings, the researchers surmise that greenness does not have a uniformly protective effect. Thus, there is a need for further investigations into the varying levels and metrics of green spaces to provide a better understanding of how greenness and air pollution influence breast cancer risk and help promote healthier living environments.