Trailblazing model Dayle Haddon dies from suspected carbon ...

Authorities in Bucks County, Pennsylvania found Haddon, 76, dead in a second-floor bedroom on Friday morning after emergency dispatchers were notified about a person unconscious at the Solebury Township home.

A 76-year-old man police later identified as Walter J. Blucas of Erie was hospitalised in critical condition.

Responders detected a high level of carbon monoxide in the property and township police said Saturday that investigators determined that “a faulty flue and exhaust pipe on a gas heating system caused the carbon monoxide leak”.

Two paramedics were taken to a hospital for carbon monoxide exposure and a police officer was treated at the scene.

As a model, Haddon appeared on the covers of Vogue, Cosmopolitan, Elle and Esquire in the 1970s and 1980s, as well as the 1973 Sports Illustrated swimsuit issue.

She also appeared in about two dozen films from the 1970s to 1990s, according to IMDb.com, including 1994’s Bullets Over Broadway, starring John Cusack.

Haddon left modelling after giving birth to her daughter, Ryan, in the mid-1970s, but then had to reenter the workforce after her husband's 1991 death.

This time she found the modeling industry far less friendly: “They said to me, ‘At 38, you’re not viable,’” Haddon told The New York Times in 2003.

Working a menial job at an advertising agency, Haddon began reaching out to cosmetic companies, telling them there was a growing market to sell beauty products to aging baby boomers.

She eventually landed a contract with Clairol, followed by Estée Lauder and then L’Oreal, for which she promoted the company's anti-aging products for more than a decade.

She also hosted beauty segments for CBS’s The Early Show.

"I kept modelling, but in a different way," she told The Times.

“I became a spokesperson for my age.”

In 2008, Haddon founded WomenOne, an organisation aimed at advancing educational opportunities for girls and women in marginalised communities, including Rwanda, Haiti and Jordan.

Haddon was born in Toronto and began modelling as a teenager to pay for ballet classes — she began her career with the Canadian ballet company Les Grands Ballet Canadiens, according to her website.

Haddon's daughter, Ryan, said in a social media post that her mother was “everyone’s greatest champion. An inspiration to many.”

“A pure heart. A rich inner life. Touching so many lives. A life well lived. Rest in Light, Mom,” she said.