Classic rock legends Lynyrd Skynyrd once riffed that “That Smell” was whiskey bottles and brand-new cars. Residents of Denver’s Elyria-Swansea neighborhood see it differently.

Plaintiffs in a recent class-action lawsuit say they’re fed up with foul odors coming from the Nestlé Purina plant at 4555 York Street, alleging the persistent stench has made it difficult to enjoy their homes and has diminished property values across the area, according to court documents obtained by the Denver Gazette.

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Filed in federal court, the lawsuit accuses the company of negligence and nuisance, claiming the factory emits nausea-inducing fumes that residents describe as “vomit-like,” “rancid,” and at times, “unbearable.”

The plant has been in the neighborhood since the 1930s, but complaints from nearby residents have prompted code enforcement and multiple lawsuits. This most recent lawsuit, which includes four named plaintiffs, was recently filed after a prior one was dismissed, as reported by Denver Gazette news partner 9NEWS.

In 2023, a similar but separate complaint was filed by a single resident, Robert Fields, which was voluntarily dismissed in May 2024. Records do not indicate exactly why the previous case was dismissed.

In October 2023, a CDPHE inspector determined the plant “failed to ensure” that its odor emissions met state standards, resulting in a $7,000 fine and a “compliance order on consent” signed in July 2024. The city of Denver also cited the plant in 2021 and fined $12,000 for failing to mitigate odor issues, 9NEWS reported.

The most recent lawsuit, filed June 4 in U.S. District Court in Colorado, claims that residents living within a one-mile radius of the Nestlé Purina facility have endured the odors for years. The suit seeks class-action status on behalf of residents living within this zone, which encompasses over 2,000 households.

Named plaintiffs in the suit include Andrew Boyle, Cole Guffey, Jessica Owens-Neckien, and Glory Silwedel, all residents of the Elyria-Swansea neighborhood.

In court filings, plaintiffs said they cannot open their windows, use their gardens, or host guests due to the smell. Owens-Neckien said the odors are so strong they “occasionally wake her up at night,” while Silwedel said she has received tenant complaints and avoids holding gatherings at her home.

Another neighbor compared the smell to “someone (having) barfed in your backyard and then it baked in the sun.”

Independent scientific research may lend credibility to Denver residents’ claims.

A peer-reviewed study from 2016, titled A Survey of VOC Emissions from Rendering Plants, was led by Dr. Frank Alexis, an environmental scientist formerly at Clemson University. It examined emissions from rendering facilities in California.

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While the California study focused on rendering operations, similar materials and processes, such as cooking animal-derived proteins and fats, are used at the Denver York Street plant, according to the federal complaint filed by residents. The lawsuit states the facility uses “animal-derived raw proteins and animal fats, many of which are highly odiferous.”

The research found that plants processing animal fats and proteins, like those used in pet food, can emit more than 40 airborne chemicals, including ammonia, acetic acid, and butyric acid — compounds known for vomit-like or rancid odors even at low levels.

Alexis said the chemicals are “highly volatile” and can cause odor complaints and physical discomfort. The study also found that concentrations increased during warmer months, a pattern plaintiffs in the Denver lawsuit allege.

The Denver Gazette reached out to representatives of Nestlé Purina, but a spokesperson did not immediately respond to a request for comment.

In a previous statement to 9NEWS, a company spokesperson said: “Purina is a proud member of the Denver community, and we’ve operated our York Street factory since 1930. Throughout this time, we have remained committed to being the best neighbor we can be, and that won’t change.”

The case, Boyle et al. v. Nestle Purina Pet Care Co. (No. 1:25-cv-01745), is pending in U.S. District Court in Colorado before Magistrate Judge Cyrus Y. Chung.

“Call Me the Breeze”? For the plaintiffs, the wind carries more of “That Smell.”