Editing Boeing 2707 (section)

=== Environmental concerns ===
By this point, the opposition to the project was becoming increasingly vocal. Environmentalists were the most influential group, voicing concerns about possible depletion of the ozone layer due to the high altitude flights, and about noise at airports, as well as from [[sonic boom]]s.<ref name=env/>

The latter became the most significant rallying point, especially after the publication of the anti-SST paperback, ''SST and Sonic Boom Handbook'' edited by William Shurcliff, which claimed that a single flight would "leave a 'bang-zone' {{convert|50|mi|km}} wide by {{convert|2000|mi|km}} long" along with a host of associated problems. During [[Operation Bongo|tests in 1964]] with the XB-70 near [[Oklahoma City sonic boom tests|Oklahoma City]], the path had a maximum width of {{convert|16|mi|km}}, but still resulted in 9,594 complaints of damage to buildings, 4,629 formal damage claims, and 229 claims for a total of $12,845.32, mostly for broken glass and cracked plaster.<ref name="boom">{{cite magazine |title=The Home: Learning to Love the Boom |date=May 7, 1965 |url=http://www.time.com/time/magazine/article/0,9171,898753,00.html#ixzz0br7nzwGf |archive-url=https://web.archive.org/web/20130824020826/http://www.time.com/time/magazine/article/0%2C9171%2C898753%2C00.html |archive-date=August 24, 2013 |magazine=Time}}</ref> As the opposition widened, the claimed negative effects increased, including upsetting people who do delicate work (e.g., brain surgeons), and harming persons with nervous ailments.<ref name=env/>

One concern was that the water vapor released by the engines into the stratosphere would envelop the earth in a "global gloom". Presidential Adviser [[Russell Train]] warned that a fleet of 500 SSTs flying at {{cvt|65000|ft|m}} for a period of years could raise stratospheric water content by as much as 50% to 100%. According to Train, this could lead to greater ground-level heat and hamper the formation of [[ozone]].<ref name=env/> Later, an additional threat to the ozone was found in the exhaust's [[nitrogen oxide]]s, a threat that was later validated by [[MIT]].<ref>{{cite magazine |title=Environment: Pre-Mortem on the SST |url=http://www.time.com/time/magazine/article/0,9171,904113,00.html |date=September 9, 1974 |archive-url=https://web.archive.org/web/20130813201813/http://www.time.com/time/magazine/article/0%2C9171%2C904113%2C00.html |archive-date=August 13, 2013 |magazine=Time}}</ref> More recent analysis in 1995 by David W. Fahey, an atmospheric scientist at the [[National Oceanic and Atmospheric Administration]], and others found that the drop in ozone would be from 1 to 2% if a fleet of 500 supersonic aircraft was operated.<ref>{{cite web |url=http://stason.org/TULARC/science-engineering/ozone-depletion-intro/24-Will-commercial-supersonic-aircraft-damage-the-ozone-laye.html |title=24 Will commercial supersonic aircraft damage the ozone layer? |access-date=August 25, 2012 |url-status=live |archive-url=https://web.archive.org/web/20160606051736/http://stason.org/TULARC/science-engineering/ozone-depletion-intro/24-Will-commercial-supersonic-aircraft-damage-the-ozone-laye.html |archive-date=June 6, 2016 }}</ref> Fahey expressed the opinion that this would not be a fatal obstacle for an advanced SST development.<ref>{{cite web|url=https://www.baltimoresun.com/1995/10/08/increase-in-supersonic-jets-could-be-threat-to-ozone-u-2-plane-trails-concorde-studies-exhaust-particles/ |title=Increase in supersonic jets could be threat to ozone U-2 plane trails Concorde, studies exhaust particles |date=October 8, 1995 |work=The Baltimore Sun |access-date=December 21, 2012 |url-status=live |archive-url=https://web.archive.org/web/20160901085907/http://articles.baltimoresun.com/1995-10-08/news/1995281022_1_ozone-sulfur-exhaust-particles |archive-date=September 1, 2016 }}</ref>

During the 1970s the alleged potential for serious ozone damage and the sonic boom worries were picked up by the [[Sierra Club]], the [[National Wildlife Federation]] and the [[The Wilderness Society (United States)|Wilderness Society]].<ref>{{cite magazine |title=Nation: The Congress: Score One for Persistence |url=http://www.time.com/time/magazine/article/0,9171,944189,00.html#ixzz0brCA4jli |magazine=Time |date=December 14, 1970 |archive-url=https://web.archive.org/web/20130822173308/http://www.time.com/time/magazine/article/0%2C9171%2C944189%2C00.html |archive-date=August 22, 2013}}</ref> Supersonic flight over land in the United States was eventually banned, and several states added additional restrictions or banned Concorde outright.

Senator [[William Proxmire]] (D-Wisconsin) criticized the SST program as frivolous federal spending.<ref name=env/>

Halaby attempted to dismiss these concerns, stating "The supersonics are coming−as surely as tomorrow. You will be flying one version or another by 1980 and be trying to remember what the great debate was all about."<ref name="env">{{cite magazine |title=Environment: SST: Boon or Boom-Doggie? |magazine=Time |date=June 1, 1970 |url=http://www.time.com/time/magazine/article/0,9171,878301,00.html#ixzz0br58gMiL |archive-url=https://web.archive.org/web/20130822171440/http://www.time.com/time/magazine/article/0%2C9171%2C878301%2C00.html |archive-date=August 22, 2013}}</ref>