Reverse-Air type baghouse filter for controlling air pollution.
Unknown author<span style="display: none;">Unknown author</span> (US government)
<a rel="nofollow" class="external text" href="http://www.osha.gov/SLTC/silicacrystalline/dust/chapter_4.html">Chapter 4: Collecting and Disposing of Dust</a>. <a href="https://en.wikipedia.org/wiki/en:OSHA" class="extiw" title="en:en:OSHA">OSHA</a> / US <a href="https://en.wikipedia.org/wiki/en:Department_of_Labor" class="extiw" title="en:en:Department of Labor">Department of Labor</a>.