A Behaviour Works Australia survey at the end of 2019 found 70 per cent of respondents avoided single-use plastics more than half the time, and the biggest motivation was knowing others were too.

Author Kim Borg said avoidance had become normal, and the study found the biggest motivator to avoidance was knowing everyone else was doing it too.

"Typically what we think is normal is what we think everyone else is doing," she said.

"It's also what we think other people approve and disapprove of.

"Because we're in this weird period were things are changing, we look to others a lot more for what is normal because we don't have our own personal point of reference."

As the wave of coronavirus hit Australia in March, cafes and restaurants were reduced to takeaway only and stay-at-home orders came into place.

Reusable cups went to the back of the cupboard, as coffee cups, takeaway packaging and online shopping piled up.

Gungahlin's Atlas Cafe was one of many Canberra venues that stopped taking reusable coffee cups as a result, in a bid to protect staff and customers.

"We don't want to be part of the problem, we want to be part of the solution," manager Sarah Ramsay said.

The cups on offer were compostable, Ms Ramsay said, a reassurance to environmentally conscious customers.

Some cafe owners said they couldn't be sure customers' cups had been properly cleaned, and it was safest to implement a blanket ban.

Experts say reusable items are safe to use provided they are cleaned regularly.

More than 100 scientists from 18 countries published a statement to reassure the public that reusables were a safe option.

"Based on the best available science and guidance from public health professionals, it is clear that reusable systems can be used safely by employing basic hygiene," the statement read.

"Single-use plastic is not inherently safer than reusables, and causes additional public health concerns once it is discarded."

Ms Borg said there was a perception single-use items were more hygienic, and after one company said no to reusables, a chain reaction began.

"If we hear a big company like Starbucks are no longer accepting reusables we make some inferences about why they might be doing that," she said.

"There is this perception single-use has increased our hygiene."

Canberrans are keen to see an end to single-use plastic items. An ACT government survey last year found about 90 per cent supported phasing out several items including coffee cups, takeaway containers and straws.

This year, the government will introduce legislation to phase out the sale and distribution of some single-use plastics.

In South Australia, similar legislation was put on hold due to the pandemic.

Ms Borg said it was likely the community would return to previous plastic-avoidance habits quite easily, but would need to move past the perception single-use was safer.

"Because a lot of people were in the habit of doing these things before COVID-19, it should be relatively easy to do it the second time around," she said.

"One of the biggest predictors of future behaviour is past behaviour."

Clean Up Australia chair Pip Kiernan said changing habits and a necessary increase in single-use items had exacerbated plastic production which ended up as litter or in landfill.

"Habits have changed significantly during this period where we're not going to restaurants, we're ordering takeaway which comes with its own single-use packaging, and we're doing a lot more online shopping which is heavily packaged in plastic," she said.

"I'm hopeful there's enough momentum in this country now that we will go back to having that sense of urgency around solving our plastic pollution challenges."

Ms Kiernan said the solution needed to be led by government and business and called for incentives for manufacturers to use recycled products.

"At the moment virgin plastic is much cheaper than recycled plastic because the price of oil - which is a component of all plastics - is so much lower with the lower demand," she said.

"So if you're not buying recycled products, not as many will be made."

Gungahlin's Atlas Cafe and many others across the city are now accepting reusable cups again, just in time for Plastic Free July, an international movement aimed to reduce plastic use.

Ms Borg suggested people look to "private" plastic use in their home if they couldn't return to "public" habits.

"If you look around your bathroom or your kitchen you will find so many different items that come in single-use plastic that you can switch out," she said.

"For those who do want to cut down on single-use plastic in public as long as people are following the proper hygiene practices the safety element is fine."

Sustainability advocate Maddie Diamond has been encouraging the community to reduce litter throughout lockdown.

Ms Diamond founded volunteer-run organisation Trash Gather, which runs regular clean-ups around Canberra, three years ago.

Gatherings stopped during lockdown, which prompted an online "Quaran-clean" event with volunteers from across the ACT, Tasmania, South Australia and NSW joining in to clean up in their area.

"When people go and clean up for the first time, they are quite shocked," she said.

She said litter was just as prevalent in the territory during lockdown but new items such as masks were being found.