Editor,
In a letter in Tuesday's Daily Lobo, Donii Fox said that backpack vacuum cleaners are light and quiet. Last night, I weighed the backpack vacuum carried by a diminutive female custodian. It weighed 14 pounds - 19 pounds when including the wand and electric cord.
These vacuums are closer to the ear than an upright vacuum, whose motor rests on the floor. Since the decibel formula is b = 10*log(I/N), where I is the intensity and N a nominal intensity (the threshold of hearing), and since sound falls off as the square of the distance, the closeness of the backpack motor to the ear results in an extra term - 10*log(25) = 14 - to the 74-79 decibel level Ms. Fox said.
The biologically effective sound-level range is about 88 to 93 decibels. Most of this range exceeds OSHA's Permissible-Exposure Limit for Noise, and all of it surpasses the OSHA action level of 85 decibels.
If Fox had ever used a backpack vacuum cleaner for an eight-hour shift, she would know that it is an excessive burden and a threat to one's hearing.
Kevin Cahill
Physics professor
