Noise - EPA Protective Levels

The noise level should not exceed certain values to protect public health and welfare.

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According to the Environmental Protection Agency - EPA - the Day-Night Sound Levels - L_dn - and the Equivalent Sound Level - L_eq - should not exceed certain limits to protect public health and welfare.

Values that should not be exceeded:

Effect	Level	Area
Hearing	L_eq(24) < 70 dB_A	All areas
Outdoor activity interference and annoyance	L_eq < 55 dB_A	Outdoors in residential areas and farms where people spend varying amounts of time in which quiet is a basis for use
Outdoor activity interference and annoyance	L_eq(24) < 55 dB_A	Outdoor areas where people spend limited time such as school yards playgrounds, etc.
Indoor activity interference and annoyance	L_eq < 45 dB_A	Indoor residential areas
Indoor activity interference and annoyance	L_eq(24) < 45 dB_A	Indoor areas with human activities such as schools, etc.

Outdoor yearly L_dn levels protect public health and welfare if they do not exceed 55 dB in sensitive areas as residences, schools, hospitals, etc.
Inside buildings yearly L_dn levels protect public health and welfare if they do not exceed 45 dB.

Note! To protect against hearing damage, one's 24-hour noise exposure at the ear should not exceed 70 dB.

Life Expectancy - Age and life expectancy for men and women.
Noise - Acceptable dB_A Level - Acceptable noise - dB_A - level at typical common locations.
Noise Exposure - Permissible Levels and Duration - Exposure to noise should be controlled so that it is less than a maximum combination of exposure level and duration.
PNC - the Preferred Noise Criterion - A noise measurement system for continuous or ambient noise in indoor environments.
Preferred Noise Criterion (PNC) - Calculator - An online Preferred Noise Criterion (PNC) calculator.
SIL - the Speech Interference Levels - Background noise frequencies that interferes with speech.
Sound - Hearing Threshold vs. Age - Shift in hearing threshold for men and women vs. age.
Sound - L_dn - Day and Night Level - The EPA A-weighted sound level day and night equivalent definition - L_dn - for a 24 hour period.
Sound - L_eq - Equivalent Level - The EPA Equivalent Sound Level - L_eq - quantifies the noise environment to a single value of sound level for any desired duration.
Sound Propagation - the Inverse Square Law - Doubling of the distance from a noise source reduces the sound pressure level with 6 decibel.