With pulp mill closure, will Prince George still be marked by 'the smell of money'?

As visitors drive into the city of Prince George, they are often greeted by a distinct aroma resembling sulfur and rotten eggs.

Locally, it's referred to as "the smell of money" due to the longstanding understanding that the scent is generated by pulp mills, which have long been the city's economic backbone.

But this week, pulp production at one of those mills is coming to a close.

That has some in the city wondering whether the "smell of money" will stop being a feature of the community — for better, and for worse.

'How will I know I'm nearly home?'

Although the scent is often a hit to the city's reputation among tourists, many locals have learned to tolerate it and, in some cases, even embrace it.

In a Reddit thread about the mill closure, one user asked, "How else will I know I'm nearly home during road trips?" while another asked: "Is this the end of the stinky PG meme?"

The "smell of money" phrase was even turned into a piece of art in a 2015 exhibit, titled The Hometown Project, which highlighted cultural touchstones of Prince George.

Though it's not a consistent smell, and it's not usually noticeable in most neighbourhoods, it's persistent enough that residents take a keen interest in finding ways to reduce it, primarily through the Prince George Air Improvement Roundtable, which brings together researchers, industry and government to find ways to reduce emissions.

Peter Jackson, a meteorologist at the University of Northern British Columbia who has devoted much of his career to studying the smell, says it's difficult to say how much it will be affected by the pulp mill industry's decline.

One reason is that despite popular belief, pulp mills are not the sole source of the smell.

There are also some misconceptions about whether the stinky air is bad for human health, he said.

Where does the smell come from?

Prince George has three pulp mills, all run by Canfor: Northwood, Intercontinental, and Pulp and Paper.

Intercontinental and Pulp and Paper sit side by side in the river valleys of the Fraser and Nechako, on a tract of land that also includes a refinery and other industrial activity, about three kilometres east of the downtown core.

Pulp and Paper, the larger of the two, stopped producing pulp this week. The paper production line will continue.

In an interview with CBC's Daybreak North, Jackson said the smell most people notice is caused by a group of compounds known as total reduced sulphur, which come from the mills — as well as other sources, like wastewater treatment plants and the landfill.

Why is the smell so strong in Prince George?

The air is frequently trapped in the city due to a geographical feature known as "the bowl" — the river valley of the Nechako and Fraser Rivers, about 150 metres lower than  the surrounding area.

When air at higher elevations is warmer than air in the bowl, it can act as a lid, causing the odour to stick around and become more pronounced, Jackson explained.

That's why people driving into the city from higher elevations will often notice the scent as they descend into the valley, and why it isn't noticeable in neighbourhoods at higher elevations.

Is the smell bad for you?

Despite its rotten stench, Jackson said stinky air isn't necessarily unhealthy.

One reason the smell is so noticeable, he said, is because it's the same one emitted by rotting food, which "we certainly want to avoid."

But that sensitivity also means we can detect the scent of total reduced sulphur at "a thousandfold less than what the health impact would be."

He added that while mills emit large plumes of smoke into the air, the sulphuric smell is actually coming from leaks closer to the ground, which Canfor has worked to reduce over the years.

The larger health issue, Jackson said, is particulate matter, particularly PM2.5, which comes from industry and traffic emissions, road dust and wood burning stoves.

People are more reliant on air quality monitors and warnings from Environment Canada for elevated levels of PM2.5.

Will air quality improve when a pulp mill closes?

Jackson said air quality will improve when a pulp mill shuts down — but by how much is tough to say.

Pulp and Paper will no longer produce pulp, but the paper line remains, so some emissions will continue alongside those from other mills. 

But, he said, he certainly predicts a reduction in PM2.5 emissions over time.

"In terms of odour, that's a bit tricker, actually, to sort out," he said, adding that weather patterns such as wind, rain and heat all have a large impact on the ambient air.

"Because of that it's really hard to tease out trends over time, but we'll be looking for it."