Table 3.
Associations between long-term exposure to PM2.5 and total mortality across greenness groups in North Carolina and Michigan
| HR (95% CI) | ||
|---|---|---|
| NC | MI | |
| Total | 1.12 (1.12–1.13) | 1.01 (1.00–1.01) |
| Greenness | ||
| Low | 1.10 (1.09–1.12) | 1.06 (1.05–1.07) |
| Medium | 1.18 (1.17–1.20) | 0.93 (0.92–0.94) |
| High | 0.98 (0.97–0.99) | 0.96 (0.94–0.97) |
HR calculated per 1 μg/m3 for PM2.5; Models were stratified by greenness groups.
Greenness was divided in groups of low, medium, and high as tertiles in each state; state-specific cutoffs for greenness group: low (<0.61), medium (0.61–0.65), and high (≥0.65) for NC; low (<0.45), medium (0.45–0.49), and high (≥0.49) for MI
N for low 418,701 persons, medium 423,138 persons, and high greenness 421,850 persons for NC; low 438,905 persons, medium 437,486 persons, and high greenness 442,167 persons for MI
Adjusted for sex, race, age group, Medicaid eligibility, cluster of PM2.5 composition, year, temperature, relative humidity, percentage Black, percentage Hispanic, median household income, percent below poverty, and population density