高齢者の死亡率と空気の汚染への短期的曝露の関連
Qian Di1, Lingzhen Dai1, Yun Wang2
1Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts.
JAMA
|December 28, 2017
まとめ
短期的な微細粒子 (PM2.5) とオゾンへの曝露は,現在の米国空気の品質基準を下回るレベルでも,死亡リスクを大幅に増加させます. これらの結果は,国家環境空気品質基準 (NAAQS) の再評価の必要性を示唆しています.
科学分野:
- 環境 健康
- 流行病学
- 公衆衛生
背景:
- 米国環境保護庁 (EPA) は5年ごとに国家大気質基準 (NAAQS) の見直しを義務付けられています.
- 死亡リスクと現在のNAAQS以下の空気汚染レベルを関連付ける証拠は,特に敏感な集団と監視されていない地域では限られている.
研究 の 目的:
- 現在のNAAQS以下のレベルでの環境微細粒子 (PM2.5) とオゾンへの短期的な曝露とアメリカ大陸における死亡率との関連を評価する.
- 空気質基準の改定の可能性を把握する.
主な方法:
- 日々のPM2.5とオゾン曝露と死亡率との関連を分析するために,条件付きロジスティック回帰を用いたケースクロスオーバー設計が採用されました.
- この研究は,39,182の郵便番号にわたるメディケア人口 (2000年−2012年) の大規模なデータセットを使用した.
- 1kmのグリッドで検証された予測モデルを使用して,毎日の大気汚染レベル (PM2.5とオゾン) を推定した.
主要な成果:
- PM2.5の10μg/m3と暖かい季節の10億分のオゾンによる短期的な増加は,それぞれ1.05%と0.51%の毎日の死亡率の増加と関連していました.
- これらの関連性は,現在の毎日のNAAQS以下の汚染レベルで観察され,死亡者の93.6%がPM2.5レベルが25μg/m3以下で,オゾンレベルが60ppb未満の日は91.1%であった.
- 汚染物質のいずれかの曝露-反応関係において,値の証拠は見つかりませんでした.
結論:
- 短期間のPM2.5とオゾンへの曝露は,現在の米国国内空気の質基準を下回ると,死亡リスクが著しく増加します.
- この結果は,現在のNAAQSが十分に保護的ではないことを示唆し,再評価を正当化している.
- この研究は,低濃度でも大気汚染が公衆衛生に及ぼす影響を強調しています.
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