"These women have remained covered up and self-conscious their whole lives," photographer Ian Ross Pettigrew tells PEOPLE

Imagine being a woman who is battling a life-threatening disease. Now picture being asked to pose for a photographer, scars and all.

Canada-based professional photographer Ian Ross Pettigrew, 46, started a photo series in August titled “Salty Girls” that features portraits of women with cystic fibrosis showcasing their natural beauty and bravery while fighting a deadly illness.

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“The message is simple: Cystic fibrosis is a fatal, genetic disease with no cure yet. Yes, these women are beautiful, and brave and powerful. Their personal stories are absolutely inspiring. But some days they feel like Sisyphus,” Pettigrew tells PEOPLE, referencing a Greek mythological king condemned to an eternity of rolling a boulder up a hill.

The 46-year-old, who was diagnosed with CF at 38, explains that Salty Girls refers to one of the common side effects of the disease – having extremely salty skin.

The project shows women between the ages of 20 and 40 in an outfit of their choice. Some choose to pose nude, others in underwear or more covered up.

“I know how out of their comfort levels they must be. To actually photograph them, and the confidence they get afterwards, and the camaraderie from being part of this, it’s so inspiring,” Pettigrew says.

At first, Pettigrew had to heavily promote the project to women via social media, blogs and chat rooms. But now the series has nearly 60 participants, and new subjects have begun contacting him for Salty Girls portraits.

“We are talking about body issues; these women have remained covered up and self-conscious their whole lives,” he says. “Now we are asking them to pose and show the world the scars that made them cover up in the first place.”

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The all-female project, which is set to be published as a book in September, stemmed from his prior photo series “Just Breathe: Adults with Cystic Fibrosis“. The original series included both men and women.

“As that project progressed it was clear that there was a disproportionate amount of women, and it was remarked that ‘this project is just a bunch of beautiful women with cystic fibrosis,’ ” he says.

But whether Salty Girls inspires young girls with CF, adult women or men, Pettigrew is convinced the movement will make a difference.