Airport Impact Overlay District Update

News and Announcements

FAA Community Process to Mitigate Aircraft Noise within the AIOD

About the AIOD

  • The Airport Impact Overlay District (AIOD) is a zoning designation for properties where airport noise is anticipated at specified levels. Properties located within the AIOD are subject to certain land use regulations. 
  • The AIOD was implemented by the Board of Supervisors in the early 1990s to mitigate impacts to prospective homebuyers in areas that would be affected by aircraft noise and to prevent residential development in areas where the highest noise impact to people on the ground is anticipated to occur. 
  • The amendments to the AIOD map adopted January 17, 2023, affect approximately 59,000 properties around and near Dulles Airport, including those removed from the overlay district.
  • Impacted residents may view the interactive map illustrating the adopted Airport Impact Overlay District to identify the current AIOD designation for their properties based on the Board’s vote.
  • In some instances, the AIOD boundaries bisect individual properties. Any property owner with questions about how the adopted AIOD impacts their property may contact the Loudoun County Department of Planning and Zoning by email or by phone at 703-777-0246.
  • The Metropolitan Washington Airports Authority (MWAA), which operates Dulles International Airport, updated its noise exposure maps for Dulles Airport in 2019. As a result, Loudoun County’s previous AIOD became outdated. Based on the airport’s updated noise exposure maps, Loudoun County worked collaboratively to update the boundaries of the overlay district as well as the county’s land use policies and zoning regulations related to the AIOD.

AIOD Overview

The AIOD indicates where airplane noise is anticipated to affect residential, school and commercial buildings. Loudoun County government cannot regulate airport noise or control flight paths; however, the county can update its policies that regulate the use of land around the airport. The previous overlay district was implemented by the Board of Supervisors in the early 1990s to both prevent residential development in areas that would be affected by aircraft noise and mitigate impacts to prospective homebuyers. 

The Metropolitan Washington Airports Authority updated the noise exposure maps for Dulles Airport in 2019. The update reflects changes in the aviation environment in the last 30 years and prepares for future changes in airport usage. Based on the airport's updated noise contours, Loudoun County amended its 2019 Comprehensive Plan to update policies related to the AIOD, which potentially affect about 59,000 property owners around and near Dulles Airport. 

The Federal Aviation Administration has established the Day-Night Average Sound Level (DNL or Ldn) as a measure of community noise; this measure calculates the average noise level over a 24-hour period. Three tiers of noise are included in Loudoun’s AIOD:

  • Ldn 65 or Higher: Properties located within this area are closest to the airport. New residential development is not permitted in this area.
  • Ldn 60-65: Properties located within this area are closer to the airport. Any residential development in this area requires disclosures at the time of sale; acoustical treatments for new residential construction and new additions to existing residences; and an easement established prior to construction of a new residence granting the right of overflight in the airspace above the property.
  • One-Mile Buffer: Properties located within this area are farthest from the airport while still being located within the AIOD. This designation requires a disclosure notice to be included with each sale of residential property.

Contact Information

Members of the public who have questions about AIOD should contact the Department of Planning and Zoning by email or by phone at 703-777-0246.

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