Meta-analysis reveals link with long-term exposure to fine particulate matter, nitrogen dioxide, and black carbon<\/p>\n<\/h3>\n
By Lori Solomon HealthDay Reporter<\/b>
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TUESDAY, July 29, 2025 (HealthDay News) — Long-term exposure to outdoor air pollution may increase the risk for dementia, according to a review published online July 24 in The Lancet Planetary Health<\/em>.<\/p>\n Clare B. Best Rogowski, from the University of Cambridge in the United Kingdom, and colleagues conducted a systematic literature review and meta-analysis to assess the link between outdoor air pollution and the risk for dementia.<\/p>\n Based on 32 included studies, the researchers found that a dementia diagnosis was significantly associated with long-term exposure to fine particulate matter (PM2.5<\/sub>; 21 studies, about 24\u2009million people; pooled adjusted hazard ratio [HR] per 5 \u03bcg\/m3 <\/sup>increase in exposure, 1.08; 95 percent confidence interval [CI], 1.02 to 1.14; I<\/em>2<\/sup> = 95 percent); nitrogen dioxide (16 studies, about 17.2 million people; pooled adjusted HR per 10 \u03bcg\/m3<\/sup> increase, 1.03; 95 percent CI, 1.01 to 1.05; I<\/em>2<\/sup> = 84 percent); and black carbon\/PM2.5 <\/sub>absorbance (six studies, about 19.4\u2009million people; pooled adjusted HR per 1 \u03bcg\/m3<\/sup> increase, 1.13; 95 percent CI, 1.01 to 1.27; I<\/em>2<\/sup> = 97 percent). There was no significant association seen for exposure to nitrogen oxides (five studies, 241,409 people; pooled adjusted HR per 10 \u03bcg\/m3<\/sup> increase, 1.05; 95 percent CI, 0.97 to 1.13; I<\/em>2<\/sup> = 44 percent); PM10<\/sub> (four studies, 246,440 people; pooled adjusted HR per 15 \u03bcg\/m3<\/sup> increase, 1.52; 95 percent CI, 0.80 to 2.87; I<\/em>2<\/sup> = 82 percent); or annual ozone (four studies, 419,972 people; pooled adjusted HR per 45 \u03bcg\/m3<\/sup> increase, 0.82; 95 percent CI, 0.35 to 1.92; I<\/em>2<\/sup> = 69 percent), with moderate to considerable heterogeneity between studies in these pooled analyses. Overall, the certainty of evidence of studies was moderate.<\/p>\n “Efforts to reduce exposure to these key pollutants are likely to help reduce the burden of dementia on society,” Rogowski said in a statement. “Stricter limits for several pollutants are likely to be necessary targeting major contributors such as the transport and industry sectors.”<\/p>\n