Green near home was linked to less inflammation. Walkable streets, not clearly.

Cohort study. 2,008 people. clinic visits 1999-2000 to 2015-2017 (up to 6 visits, 8,980 observations).

People were watched for years. Nobody was told what to do. A clue, not proof.

Who: US midlife women (aged 42-52 at SWAN entry; mean 49.9 at the first visit used) from 6 SWAN sites (Chicago, Detroit, Los Angeles, Newark, Oakland, Pittsburgh); 45% White, 26% African American, 12% Japanese, 10% Chinese, 7% Hispanic

• Some green (land map)-11.5%CRP, inflammation
• Greenest (satellite)-10.2%CRP, inflammation
• Medium walkability+2.0%LDL cholesterol

More to know, from our read of the paper:

• Observational: associations only, linked not proven; residual confounding possible (other pollutants like ozone/NO2, diet not accounted for)
• Outcomes are blood markers (CRP, fibrinogen, lipids etc.), not heart attacks or strokes; never claim heart disease was measured
• Not a clean dose-response: for the main land-cover measure the MEDIUM green tertile had -11.5% CRP, but the HIGH tertile's -8.0% had a CI crossing zero (-16.3 to 1.0). The satellite vegetation index (NDVI) showed the high tertile significant (-10.2%)
• Greenness was low overall: land-cover green within 1 km had 33rd/67th percentiles of only 0.37% and 5.07%; mostly urban women
• Green measured around the home address only; not park use, access or time spent in green space (authors)

Researchers followed 2,008 US women in midlife (SWAN study) with blood tests from 1999 to 2017, and used satellite maps to measure the green around each home. Women with a medium amount of green land nearby had 11.5% lower CRP, a blood marker of inflammation, than women with the least; by a second satellite measure, the greenest homes had 10.2% lower CRP. Living in a medium-walkable area was linked to 2% higher LDL cholesterol. This is observational and measured blood markers, not heart disease: linked, not proven.

We read the abstract and the full text of this paper and checked every number on this page against it (15 facts, checked on 2026-10-29). The study design is named above. Cohort and other observational studies are described as linked, not proven. Found an error? Email theis@onestudyaday.com.