Denver’s poorest residents are more likely to breathe smelly air, research finds

DENVER — An April breeze carried the smell of roasted coffee, diesel smoke and manure towards Swansea Park. 

“Depending on which direction the wind is blowing, a lot of odors coalesce [here],” said Mark Peterson, an investigator with the Denver Department of Public Health and the Environment (DDPHE). 

Anytime a resident submits an odor complaint to the city, Peterson or another investigator searches for the smelly source. Once he picks up a whiff, he follows the scent upwind until it disappears. Then he uses a sensor called a Nasal Ranger, shaped like an anteater’s snout, to measure the potency of the smell and determine if the smell is in violation of Denver’s odor ordinance. 

Detecting odor is notoriously difficult. Smells are transient, highly subjective and can travel miles from their source. 

That’s why Denver relies primarily on citizen complaints to guide its response to odor. Between 2014 and 2022, citizens submitted 100 to 200 complaints per year. If enough residents speak up, the city takes action — implementing an odor control plan or, in rare cases, issuing a citation. 

New research from the University of Colorado indicates that residents in “gentrifying areas” are more likely to submit an odor complaint to the city, even though people in “less privileged census blocks" are more likely to contain a “malodorous facility,” such as a marijuana grow operation or pet food manufacturer. 

According to Priyanka deSouza, a professor of urban planning and one of the report’s authors, it’s not surprising that smelly industrial facilities cluster in Denver’s northern and western fringes, often referred to as the “inverted L.” 

“These are neighborhoods that have been redlined. Land is cheaper, so we see a lot of industrial facilities in these neighborhoods. There’s a ton of research that has found that pollution, health and wealth outcomes are lower in these neighborhoods,” said deSouza.