|Description:||This historical drawing, provided by the Center for Disease Control's (CDC), National Institute for Occupational Safety and Health (NIOSH), detailed a design for a floating-scale electrostatic precipitator flow meter. Electrostatic precipitators are used to catch loose airborne particles leftover from incomplete industrial burning processes such as those which take place in coal-fired electrical power plants. By electrically charging, or “ionizing” the particles, the positively-charged particles then move toward negatively-charged collecting electrodes, where they are trapped. The particles adhere to the collection plates and build up into larger particles. The plates are then tapped, or “rapped”, which loosens the partcles that then fall into hoppers for collection and disposal. The flow meter design is an example of a measure meant to improve workplace safety through the accurate measurement of air quality.|
The NIOSH Historic Photo Collection began as the “picture file” of the Industrial Hygiene Division of the U.S. Public Health Service (USPHS), c. 1930-1960. It is a unique collection of mid-20th Century images of American workers and workplaces and documents occupational safety and health research of that era. The collection consists of approximately 1,000 original photographs and schematic drawings.