January 21, 2018
One of our mandates as a non-for-profit is to educate our members about the peculiarities surrounding noise exposure. (Forgive the technical nature of this post, particularly if you’re already aware of how noise is measured.)
The United States Environment Protection Agency (EPA) uses the Day-Night Sound level (DNL) metric to measure the loudness of jet aircraft over residential communities. DNL is based on sound levels measured in relative intensity of sound, or decibels (dB), on a weighted scale (dBA). This scale most closely approximates the response characteristics of the human ear to sound. Thus, the higher the number on the scale, the louder the sound. DNL represents noise exposure events averaged over a 24-hour period.
To describe and compare noise exposure from numerous single jet aircraft flyovers that vary in duration and magnitude over 24 hours, the EPA developed 65 DNL as the baseline noise metric (averaged over the full 24 hour day/night cycle) for what it considers ‘adverse’ noise. This 65 DNL noise ‘contour’ is effectively a line superimposed on a map of O’Hare and the surrounding communities. (Given the fact that the noise contour approved and redrawn for the O’Hare Modernization Plan in 2005 by the EPA and FAA, is deliberately inaccurate and based on faulty data is another issue that will be addressed in a later posts.) If a community falls within the 65 DNL, residents qualify for federally-funded homeowner sound insulation in the form of noise-cancelling windows and doors, and specialized attic acoustic insulation. Importantly, if the homeowner has not opened any windows and doors, particularly during the spring, summer and fall, human sensitivity to jet noise should be ‘ideally’ limited.
Residents within the 65 DNL contour are essentially hermetically sealed in their homes for 12 months, 24 hours a day in perpetuity. The minute a homeowner walks outside to enjoy their backyard, stroll the neighborhood, enjoy a local park, outdoor café, or farmers market, all bets are off. Everything contained within this 65DNL ‘wall’ is exposed to permanent and severe noise amplitudes for 24 hours. To illustrate, here is an example. When a jet flies over a park at an amplitude of 130 DNL for one minute and then passes the next minute followed by no noise (hypothetically 0 DNL), the official DNL reading (averaging the two events [130 DNL + 0 DNL]/2 events), is 65 DNL. The City of Chicago and the operators at O’Hare are in compliance with the EPA and FAA regulations for noise compatibility in this example. When a second jet follows close by (only a minute past the first), its noise amplitude reading is 120 DNL and then passes the next minute followed by no noise (averaging the two events [120 DNL + 0DNL]/2 events) is 60 DNL. This example is also within the tolerable noise exposure level of 65DNL by the EPA and FAA.
Regardless of the frequency, volume and altitude of flights over homes and communities, as long as residents live within this 65 DNL wall (and have accepted the funding for residential sound-proofing), they have masochistically agreed to partake in their own permanent and extreme noise exposure for the remainder of their domicile. Although that is certainly not how residents may perceive their situation, we can assure you that that IS how your local elected representative, the City of Chicago, O’Hare Airport operators, commercial airlines, and the Federal Government sees it. How do we know they see it that way? Each and every entity has confirmed that perception to FAiR NFP either verbally or in writing. Distilled down to the essence of their understanding of the situation, these leaders see it as: In exchange for the ‘privilege’ of living immediately adjacent to O’Hare and being ‘bought-off’ with federally-funded taxpayer-supported sound-proofing, you the homeowner will agree to have your quality of life severely and permanently diminished in exchange for allowing the commercial airline industry to maintain a profit, the state of Illinois and surrounding suburbs to maintain ‘economic growth’ and the City of Chicago to enhance their tax revenue through airline and passenger fees. In other words, you the resident have agreed to sacrifice and have your life exploited in order for industry and government (coordinating together against the will of the public), to make money.
When everything else is stripped away, that is how our elected leaders rationalize the situation. That is NOT how FAiR NFP understands the situation nor do we believe that is how our members see it.
Ok, so what can be done?! More to follow…..