Both the FAA and the U.S. Department of Housing and Urban Development consider exposure levels higher than DNL 65 dB to be incompatible with residential land use. DNL is the Day-Night average sound Level expressed (in decibels) as a 24-hour average. An annual average of DNLs is used by the FAA to describe airport noise exposure. Areas with noise impacts less than 65 dB DNL are considered "compatible" with residential use; areas at or above 65 dB DNL are designated "incompatible" with residential use.
Massport reports population counts by 5-decibel increments of exposure each year by community to track Logan Airport's noise environment changes over time from neighborhood to neighborhood. The counting methodology is updated over time to reflect changes in population using U.S. Census data.
In 1980, nearly 63,000 individuals resided within the 65 DNL dBA sound contour or higher. In 2005, that number had dropped to just under 6,500 individuals and there are far fewer individuals within the loudest sound contours. The steady decline in affected population is attributable to quieter aircraft and Massport's noise abatement procedures.
Population counts for 2009 by community are presented in the table below and are compared to counts since 2004.
View Table for Noise-exposed Population by Community 2005 -2010