Refer to: http://www.dot.ca.gov/dist07/resources/envdocs/docs/710study/draft_eir-eis/ Visual Impact Assessment: SR710 Visual Impact Assessment pdf, pages 209-212
Please read that "The vividness would be high--the new ventilation stacks would add a predominant visual element to this view. The element would be very memorable. Also, the new paving and striping improve the look for this entrance into Old Town Pasadena." "... the new ventilation stacks located on both sides of Colorado Boulevard would create a visual flow which follows the perspective lines toward Old Town Pasadena toward Old Town Pasadena and the new paving striping improve the look for this entrance into Old Town Pasadena. With the introduction of the ventiliation stacks contributing to the visual flow toward the center of the view, unit increases."
Peggy Drouet: Whoever designed these structures and whoever approved the design doesn't have a clue as to what the architecture of Old Town Pasadena consists of, that is, old buildings. This modern design is an insult to the city of Pasadena and to its citizens. In other words, what were they smoking? Maybe another way to look at this is that the designer wanted his/her creation to be in full international view during the Rose Parade broadcasts. He/she may expect "ooh's" and "ah's," but the reaction will be "you got to be kidding," followed by much snickering.
Note that only one of these ventilation stacks are functioning stacks. This was not mentioned in the SR710 - Draft EIR-EIS, but was at the Technical Advisory Committee TAC) meeting on March 11, 2015.
Whether the ventilation stacks are all functioning ones or not and whether they need to be redesigned or if the six stacks should be reduced to only one is not the main issue here. The issue is the placement of any ventilation stacks on Colorado Boulevard, anywhere else in West Pasadena, or anywhere else in the city or in any other city. "Vehicle exhaust cannot be properly filtered and will lead to health issues not only for the drivers who use the tunnel  but also for the surrounding communities where the exhaust is vented." http://www.no710.com/ .
But these visitors and the residents of Pasadena and surrounding communities will stop coming to eat, shop, and walk around Old Town Pasadena as soon as it becomes known that they will be exposing themselves and their families to high air pollution levels due to ventilation stacks in the immediate vicinity. I can easily vision Old Town Pasadena becoming Ghost Town Pasadena.
Remember that it took many years for Old Town Pasadena to become the great place it is today, but it won't take long to return it to what it was when I first moved to Pasadena 45 years ago--on the verge of becoming a true slum area. People will simply move out of the transit villages that Metro has felt are needed for their Gold Line to be successful, people will shop and eat elsewhere, and merchants will leave as they will have too few customers to make a good profit. There are other nice places to live, shop, and eat that are not marred by ventilation stacks.