Air Pollution Exposure and Muscle Mass and Strength Decline in Older Adults: Results From a Swedish Population-Based Study.

<p><b>BACKGROUND</b></p><p>Emerging evidence suggests that air quality may impact muscle health. However, most studies are limited by cross-sectional designs or short follow-ups.

We assessed the association of long-term exposure to ambient air pollutants with changes in muscle mass and strength in older adults.</p><p><b>METHODS</b></p><p>We included 3249 participants from the SNAC-K longitudinal study (mean age 74.3 years; 35.8% males). Muscle strength (measured through handgrip and chair stand tests), muscle mass (derived from calf circumference) and physical performance (assessed through walking speed at a usual pace) were assessed over a 12-year period.

Probable sarcopenia was defined as reduced muscle strength as per the EWGSOP2 criteria. Residential exposure to PM2.5, PM10 and nitrogen oxide (NOx) was estimated for the 5 years preceding baseline.

Cox regressions and linear mixed models examined the association of air pollutant exposure with, respectively, probable sarcopenia and longitudinal changes in muscle parameters.</p><p><b>RESULTS</b></p><p>Over 12 years, the cumulative incidence of probable sarcopenia increased with higher exposure (above vs. below the median values) to NOx (36% vs. 28%), PM2.5 (35% vs. 28%) and PM10 (35% vs. 28%).

The association between air pollutant levels and the risk of probable sarcopenia was nonlinear (p nonlinearity = 0.002 for NOx, 0.001 for PM2.5 and 0.003 for PM10), with an increased risk showing a plateau at very high levels. Higher exposures were associated with an increased risk of developing probable sarcopenia, by 25% for NOx and PM2.5 (HR 95% CI: 1.07-1.47 for both) to 33% (HR 95% CI: 1.14-1.56) for PM10.

Elevated pollutant exposure was associated with significantly greater annual declines in lower-limb strength (chair stand test: 0.40-0.48 s) and walking speed (0.004 m/s).</p><p><b>CONCLUSIONS</b></p><p>Long-term exposure to moderate levels of ambient air pollutants may increase the risk of probable sarcopenia and accelerate declines in lower-limb strength and physical performance in older adults.</p>