Residents in North Denver and Commerce City had the highest levels of fine particle pollution of anywhere in Denver or any city in Colorado during the past three months, data collected by the state shows. The exposure risked the health of some residents.
The state Department of Public Health and Environment dispatched its mobile lab to the area in May, it said in a press release, “because of department and community concerns regarding air quality in the area.” Between May 14 and July 17, the lab collected pollution data and found that fine particulate matter – emitted by vehicles, coal-fired power plants and wildfires – were high enough to pose health risks to some at-risk people, like children or people with respiratory or cardiac issues.
The pollution “comes from local sources,” the health department said, like vehicles and the Suncor refinery located in Commerce City. In a settlement with the state, Suncor agreed to spend $12 million on improving its refinery technology and operations. Wildfire smoke, another contributor, contains this type of particulate matter and comes from outside of the state from fires elsewhere. For reasons experts don’t entirely understand, local fires typically do not carry that type of pollutant when they’re fresh, researchers previously told the Gazette.
Denver leaders who for two decades have backed densification, paving over greenspace with concrete and asphalt to accommodate more people in the city, now are turning to trees for relief from worsening heat islands that amplify climate warming.
But urban ecologists and city officials say trees alone won’t be enough to keep Denver habitable as temperatures increase. They urge a far more ambitious expansion of greenspace.
“And concrete is definitely getting poured faster than we are planting trees,” city forester Mike Swanson told The Denver Post.
Heat islands — dense urban areas that are much warmer than their surroundings — have widened, data shows, with Denver emerging as one of the nation’s most “impervious,” or paved-over, cities. Older neighborhoods where houses have yards may be more resilient, researchers have found, because compared with redeveloped parts of the city, these landscapes don’t radiate as much heat.
Denver’s population has increased from 498,402 in 1998 to estimated 734,135 in 2020, a 47 % increase.
“Excluding undeveloped area around DIA, 48% of Denver is now paved over or built up. This is up from 19% in the mid-1970s. Expected to 69% by 2040.”*
With only 8% of its land used for parks and recreation, Denver has fallen from 13th place in 2012 to 22nd place in 2020 in the Trust for Public Lands Park Score for America’s 100 largest cities. In comparison, the percentages of land used for parks and recreation in some other cities are: Washington, D.C.—24%; New York City—21%; San Francisco—21%; San Diego—19%; Portland, Oregon—18%; Boston—17%; Minneapolis—15%; Los Angeles—13%; Seattle—13% and Chicago—10%. According to the Trust for Public Lands, the 2020 national median percentage of land used for parks and recreation in America’s 100 largest cities is 15%.
“Park space per person in Denver has fallen to 8.9 acres per 1,000 residents, down from 9.4 acres per 1,000 residents in 2006 and 9.5 acres per 1,000 residents two decades ago — far below the national average of 13.1 acres per 1,000 residents, city data show. (By comparison, Portland offers 23 acres per 1,000 residents.) Denver officials project the acreage will decrease further to 7.3 acres per 1,000 residents as Denver’s population tops 857,000 before 2040.”*
“It would take at least 1,500 acres of new green space to stop the decline and hold steady at about 9 acres per 1,000 residents, and 3,000 new acres of parks to approach the national norm of 13.1 acres per 1,000 residents, city planners said.”*
“Since 2012, Denver has experienced more than 50 days a year with temperatures topping 90 degrees. A 2014 Climate Central analysis of National Weather Service data found that Denver has one of the nation’s most severe ‘heat island’ effects, with a 4.9-degree increase compared with the surrounding, and mostly treeless, high prairie.”*
Denver is ranked 10th worst out of 229 metropolitan areas for ozone pollution.** In 2019, the EPA downgraded Denver’s ozone rating from “moderate” to “serious.”
According to the Denver Parks and Recreation Department’s Game Plan for a Healthy City: “The science is clear, our planet is facing a global crisis attributed largely to human behavior that is changing climate patterns around the world…. Parks, recreation, and the urban forest are vital infrastructure to our city’s health. Trees and vegetation in our parks as well as along our parkways and streets help clean the air we breathe and provide shade that decreases the cooling load on our energy infrastructure during our hot months. Our parks and urban forests hold, clean, and infiltrate stormwater, decreasing the load on our storm sewer system.”
*Source: Bruce Finley, Denver Post, January 13, 2019; **Source: American Lung Association 2020 State of the Air report