Short term exposure to air pollution and stroke: systematic review and meta-analysis
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This Research article (*BMJ* 2015;350:h1295, doi:[10.1136/bmj.h1295](https://www.bmj.com/lookup/doi/10.1136/bmj.h1295)) was mistakenly published under the CC BY NC licence initially online and in the May 2015 academic print issue, and should have been published under the CC BY licence. The online version has since been corrected.

This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 3.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See: [http://creativecommons.org/licenses/by/3.0/](http://creativecommons.org/licenses/by/3.0/).