1, residential areas, schools, hospitals, cultural reserves and other ordinary environments: daily average sound level ≤ 55 dB. Maximum sound level per hour ≤ 65 decibels. Maximum sound level per second ≤ 75 dB.
2, outdoor recreation, parks, public **** activities and other important environment: daily average sound level ≤ 50 dB. Hourly maximum sound level ≤ 60 dB. Maximum sound level per second ≤ 70 dB.