Consider Noise Level When Choosing A Fan

Fan noise is oftentimes overlooked when choosing a fan. Fan noise will vary by fan type, flow rate, pressure and fan efficiency. Other factors such as walls, floors, ceilings and other equipment will have an effect on noise reflection and absorption to varying degrees as well. Here are a few tips you will want to consider and understand before selecting a fan:

OSHA Exposure Limit

From a safety standpoint, OSHA’s (Occupational Safety & Health Administration) permissible exposure limit is 90 dBA based on a time-weighted average over an 8-hour day. Similarly, NIOSH (National Institute for Occupational Safety & Health) recommends limiting the 8-hour exposure to less than 85 dBA. It’s also important to know that decibels are measured on a logarithmic scale, which means that a small change in the # of decibels will result in a huge change in the amount of noise and potential damage to a person’s ear. For example, a thunderclap measured at 120 dBA can be over 30 times as loud as the noise at 70 dBA.

Understanding Decibel Levels

The ear is a sound pressure receptor.  To get a feeling for decibels, look at the table below which gives values for the sound pressure levels of common sounds in our environment.  When making noise comparisons, keep in mind that noise measured at 120 dBA for an extended period of time can cause pain or possible hearing loss.

Outdoor/Indoor Noise	Sound Pressure Decibel Level (dBA)
Jet aircraft at 50 ft. away	140
Threshold of pain	130
Threshold of discomfort	120
Chainsaw at 3 ft.	110
Disco at 3 ft. from speaker	100
Gas lawn mower at 3 ft.	90
Diesel truck at 50 ft. at 50 mph	80
Vacuum cleaner at 10 ft.	75
Normal speech at 3 ft.	70
Heavy traffic at 300 ft.	65
Large Business Office	55*
Library	35

 Source: www.dot.ca.gov/dist2