When disaster strikes, people often express their sympathy by donating things they think could help: used clothes, children’s toys, pairs of old shoes.

But experts say these items are often unnecessary and become burdensome to relief workers. In the case of Fort McMurray, hundreds of donated items are simply taking up space in an Edmonton warehouse.

“We have items that are dirty or things that are just not usable at this time,” volunteer coordinator Marissa McNabb told CTV Edmonton. “We have to see if it’s in a state that we can actually get it donated. If not, then we do have to find a way to get rid of it.”

The problem is hardly unique to the Fort McMurray wildfire. Similar crises across the globe have put relief workers in the awkward position of having to put donations into storage, find a different charity to take them or even throw them out.

“Most donations are really a great thing. But donations that are not needed are not cool because they pile up at ports and airports and parking lots … and usually the people who move them are relief workers,” said Juanita Rilling, director of the U.S. Center for International Disaster Information.

Alberta faced a similar problem in 2011 after a massive fire in Slave Lake triggered donations of clothes, toys and household goods to the community. Many of those donations wound up in a Calgary landfill.

The woman who organized the Slave Lake donation drive said she was “heartbroken” by the news and attempted to send the remaining donations to charity. But attempts to find a group that could use the items was challenging as several charities said they didn’t need them.

“Anything that is not needed gets in the way,” Rilling told CTV News Channel on Wednesday. “The only way to know what’s needed is to work with relief organizations on the ground who issue requests for specific things.”

The Edmonton Emergency Relief Services Society had asked for clothing earlier in the week but now says it needs new bottles of medication, new pillows and new blankets.

Similar stories of excess donations have emerged in disaster zones throughout the world.

Piles of clothing sent to Indonesia after a tsunami in 2004 were reportedly thrown in pits and burned. An estimated 65,000 teddy bears were sent to Newtown, Connecticut after a school shooting and had to be kept in a warehouse. After Haiti’s devastating earthquake in 2010, officials were unsure what to do with bottles of breast milk sent by concerned mothers to the island nation.

“This is a problem of scale; the more unneeded donations that appear, the more time that relief workers have to spend dealing with them and the less time they spend with survivors. It’s a real problem,” Rilling said.

The Canadian Red Cross has said the best way to support evacuees is through a monetary donation. The relief organization has collected $67 million as of Wednesday, and the federal government and Alberta’s provincial government have pledged to match individual donations.

“Cash donations enable relief organizations to meet needs as they change,” Rilling said. “Also, cash donations enable relief organizations to purchase supplies locally, which supports the local economy and strengthens it for the long run. There’s really no material donation that you can send that conveys all of these benefits.”

Alberta Premier Rachel Notley announced Wednesday that the province will provide adult evacuees from Fort McMurray with a one-time payment of $1,250 and minors will receive $500, which will be distributed through debit cards.

The Red Cross says it will provide $50 million, or $600 per adult and $300 per child, to evacuees.

With files from CTV Edmonton