1.   It has exhaust ducts resembling a skateboard ramp and a surprisingly low-tech steel ring comprising the nucleus of the facility.

2.   On gasoline-powered saws the muffler should be enclosed in a protective shield and the exhaust ducts should direct smoke and exhaust gases away from your face.

3.   An exhaust duct was installed to draw out dust and fumes from power machinery.

4.   An exhaust duct was installed to draw out dust and exhaust from power machinery to clean the air inside the tunnel.