The situation of gutter oil is so rampant the countrywide safety equipment began a marketing campaign in 2011 to stamp out the "four black pests" (打四黑除四害) — black workshops, black factories, black markets and black gambling dens. There was some drilling to insert cables but any dust was cleaned up. https://thestoriesofglory.blogspot.hu/search/label/url-HHsGyDomCQKwyFArt3CDokfJX