In a letter to the state sent last week, the Suncor oil refinery in admitted it released more than the reportable limit of sulfur dioxide when power went out at the plant back on October 14.

At the time, the company said the orange cloud was not hazardous. And it still insists the same in that letter, “there are no known or anticipated acute or chronic health risks associated with the release, and there is no need.”

But in that letter, Suncor also admits that it released more than the reportable quantity of 500 pounds of sulfur dioxide. It, in fact, estimates a total of 37.8 tons of sulfur dioxide was released. That’s more than 75,000 pounds.

"All I've seen is that there was this big emission,” said Dr. Anthony Gerber, an air quality expert at National Jewish Health. “But with my understanding with how we monitor air around these plants, I don't think its so easy to be definitive that there wasn't a health risk associated.”

“I don't think they have the data to definitely say we're 100 percent certain that there wasn't a plume or an area where they was a brief exceedance of this standard,” he said.

9NEWS reached back out to Suncor, which told us it complied with state health standards in determining the release did not pose a risk to the public.