• Ducts accumulate a lot of dust.Factory roof with heating and ventilation chimneys image by Christopher Dodge from Fotolia.com
  
  Duct cleaning companies are called in because the ducts are laden with dust, cooking oils and a variety of other substances. Just about anything can get sucked up through the intake. Cleaning duct work, especially in buildings, is a hazardous occupation. The Occupational Safety and Health Administration, or OSHA, understands the hazards involved and has mandates to protect workers.
  
  

Ventilation

• Before anybody does any duct work, the air must be ventilated with fresh air. This applies to any environment that produces vapors, dust, or mist. Duct cleaning falls into that category. Furthermore, there must be a flow of fresh air to blow the contaminants away from the workers and not toward them.
  
  

Air Testing

• Any time a worker has to enter an unknown area or confined space, the air must be tested for toxic gases, vapors or particulates. If anything is found, the area must be ventilated. If after ventilating the levels still exceed the limits of a respirator, a SCBA or Self-Contained Breathing Apparatus must be used. Conversely, a respirator with an outside air supply must be used. This is an important step. If the ducts run along exhaust gas flues, carbon monoxide may be present.
  
  

Personal Protective Equipment

• Use a fully enclosed respirator for high dust areas.gas mask image by diter from Fotolia.com
  
  Personal protective equipment, or PPEs, such as respirators must be worn. Other personal protective equipment includes coveralls and face shields. Many respirators designed for high dust environments are fully enclosed, protecting both eyes and breathing.
  
  

Confined Spaces

• All OSHA regulations for confined spaces are in effect before entering the duct. This includes having a pre-entry checklist. For entering large ducts in buildings, this is mandatory. Some of the items on the checklist include air testing, communication with a lookout person and emergency evacuation planning.