Editor’s note: This is the final article in a three-part series on some of the questions yet to be answered on what impact construction of the South Mountain Loop 202 will have on local residents.
While there may be a ray of hope that the South Mountain Loop 202 could be built south of Pecos Road, at this point officials are looking at the only option available in the east, which is along Pecos Road.
And one of the big questions yet to be answered is what kind of impact the freeway’s traffic would have on air quality.
Members of the South Mountain Citizens Advisory Team have pleaded with the Arizona Department of Transportation to bring in experts to discuss what 165,000 vehicles a day on the Loop 202 would do to air quality, especially the impact on children at the five public schools that are from 50 to 1,500 meters from the proposed freeway right of way.
But ADOT has insisted that any air quality discussions wait until the draft environment impact statement is ready to be released, because the topic is complex and any discussion should be project specific.
But a report by the University of California at Los Angeles may toss a wrench into ADOT’s plans to get approval for the eight-lane freeway.
The report released in June shows that freeway air pollution extends much further than originally thought … more than 2,500 meters or 1.5 miles in the case of Interstate 10 through Santa Monica, Calif.
The pre-dawn pollution distance was 10 times further than the daytime pollution impact previously measured.
But researchers also discovered that the pollution concentration levels were higher than that found in daytime, even though there was just a fraction of the daytime traffic.
“Our finds confirm previous work showing peak levels of ultra fine particles immediately adjacent to the freeway, but we found high concentrations persisted for up to 1.5 miles downwind from the freeways during the pre-sunrise hours,” said Dr. Scott Fruin of the University of Southern California School of Medicine, who also participated in the study.
For Ahwatukee Foothills that could be bad news since South Mountain acts as a wall on the north side of the proposed freeway and winds often blow from the south, setting up the possibility of ultra fine particles held over Ahwatukee Foothills during the night.
Generally speaking, most models show that vehicles traveling at highway speeds, even when stuck in rush-hour traffic, produce less air pollution than an equal number of vehicles stuck on surface streets in stop-and-go traffic.
But a challenge in Nevada by the Sierra Club, arguing that widening U.S. 95 would create an air quality threat to nearby schools, was settled with the Nevada Department of Transportation, agreeing to extra air-filtering systems at the schools and special monitoring to see what impact the fine 2.5 micron particulates, called PM 2.5, would have on the health of children and nearby residents.
That settlement agreement was limited to Las Vegas, but it opened the door that PM 2.5 pollution near freeways is a health concern, because it can easily be drawn deep into the lungs.
A draft environmental impact statement on the Loop 202 is in the final revision stage and could be made public by this summer. At that point, ADOT plans to hold several meetings to discuss air quality in general and air quality impacts the Loop 202 might pose for Ahwatukee Foothills.
But until then, residents will have to wait to see how the addition of a major freeway along the southern border of Ahwatukee Foothills will impact air quality and health.