CSIRO scientists say invisible toxic pollutants are fouling the atmosphere, even in the world's cleanest air at a monitoring station in far north-west Tasmania.

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The category of persistent organic pollutants (POPs) includes DDT, pesticides and dioxins, and as the name suggests they do not dissipate easily.

They are being detected even at Cape Grim station, in far north-west Tasmania, one of the most important research sites for the pollutants in the world.

While people may have never heard of them, senior CSIRO scientist Melita Keywood says it is important to keep monitoring them and eliminate new dangerous compounds.

"They can have quite a bad impact on human health," she said.

"For example, they can result in reproductive problems for people, and they can also impact people's respiratory health and heart function."

Dr Keywood says the pilot program monitoring atmospheric pollution should be extended beyond its current three-year timeline.

"We're hoping that this'll continue for a very long period of time because we need to know long-term trends," she said.

"We need to know if these compounds are being removed from the atmosphere over a long period of time."

She says the air is very clean off Cape Grim because it has not been in contact with land for a long time.

But even at Cape Grim there are signs of persistent organic pollutants that may have been used on the other side of the world.

"If we see some of these pollutants in samples we're collecting, that tells us that they've been able to circulate right around the globe to get to the background air atmosphere," Dr Keywood said.

"[There are] things like dioxins and pesticides, some pesticides that have been used in the past.

"They're also things like fire retardants and also PCBs (polychlorinated biphenyls) - so things that have been used in the past a lot and are still being used today."

Cape Grim research centre manager Sam Cleland says the centre is uniquely placed to do an important global job.

"It's one of the most important places to measure what the global pollution levels are because what we get is mixed right through the whole world," he said.

"We're perched over a hundred-metre tall cliff and when we look west the nearest land is South America."