The problem of gutter oil is so rampant that the national protection apparatus started a 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 a little drilling to insert cables but any dust was cleaned https://mylittlebookmark.com/story5558040/the-smart-trick-of-cctv-installation-in-wakefield-that-nobody-is-discussing