Dayle Haddon: Former Sports Illustrated model dies of suspected ...

Dayle Haddon - the actor, activist and former Sports Illustrated model - has died from what authorities believe was carbon monoxide poisoning.

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

A 76-year-old man, later identified as Walter J Blucas, of Erie, is in a critical condition.

Responders detected a high level of carbon monoxide in the property.

Investigators believe the leak was caused by "a faulty flue and exhaust pipe on a gas heating system".

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, 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 re-enter the workforce after her husband's 1991 death.

This time, she found the modelling industry far less friendly: "They said to me, 'At 38, you're not viable'," Haddon told The New York Times in 2003.

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Working for an advertising agency, shebegan 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 Estee 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.

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

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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.