Sangamon County, IL Noise Ordinances: Decibel Limits (2026)
Key Facts
- Governing chapter
- Title 17, Chapter 17.34
- Districts covered
- I-1 and I-2 industrial districts only
- Lowest band limit
- 72 dBA at residential boundary
- Certification required
- Registered engineer or approved lab
Summary
Sangamon County caps industrial plant noise at the district boundary: 72 decibels in the lowest octave band at a residential boundary, 79 near a business district, measured with a certified sound level meter.
At no point on the boundary of a residence or business district shall the sound pressure level of any operation or plant (other than background noises not directly under the control of the manufacturer) exceed the decibel limits in the octave bands designated below:
Octave Band Frequency (cycles per second) Along Residence District Boundaries Along Business District Boundaries 0 to 75 72 79 75 to 150 67 74 150 to 300 59 66 300 to 600 52 59 600 to 1,200 46 53 1,200 to 2,400 40 47 2,400 to 4,800 34 41 over 4,800 32 39 (Res. 1-1 §5(S) (2), November 16, 1982)
Full Breakdown
Chapter 17.34 sets performance standards for new industrial uses in the I-1 and I-2 districts. Section 17.34.020 requires sound levels to be measured with a sound level meter and octave-band filter meeting American Standards Association specifications, and bars any plant or operation from exceeding decibel ceilings at eight octave bands: from 72 dBA (0-75 cps) down to 32 dBA (over 4,800 cps) at a residence district boundary, and 79 dBA down to 39 dBA at a business district boundary. An engineer's certification of compliance must accompany the zoning certificate application.
Violations & Fines
Noncompliant industrial uses can be denied a zoning certificate; the county requires certification from a registered engineer or approved testing laboratory before approval, and existing uses cannot expand in a way that worsens a violation.
Frequently Asked Questions
Does this noise limit apply inside Springfield or Chatham?
What decibel limit applies near a home?
Sources & Official References
Other rules in Sangamon County
Compare Sangamon County to another location·View the Illinois noise ordinances overview
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