A mysterious blue powder inside a blank Christmas card delivered to a family home sparked a full-scale alert.
The Rout family have spoken of their shock at their road being closed after they received the suspicious envelope.
North Road in Banwell was swarming with police cars, ambulances, decontamination specialists from the fire service and the Hazardous Area Response Team on Wednesday afternoon.
A public safety alert was caused when Sharon Rout picked up her post and opened a white envelope stamped and addressed to her and husband Andy.
As soon as her finger tore through the seal, blue powder started to seep out so she went over to the bin to empty it. Inside the envelope was a blank Christmas card.
Mr Root, a Weston-super-Mare coastguard, returned home not long afterwards and was as bemused as Mrs Rout as to what the substances was and why it had been sent.
Mrs Root called the police and within minutes half a dozen police cars, half a dozen ambulances and people dressed in bio-hazard suits were on the normally peaceful street.
The road was shut for four hours until 6.15pm, when the substance was taken away for testing.
Yesterday, Avon and Somerset police spokesman Martin Dunscombe said the powder had turned out to be harmless, but said he could not release what it actually was.
Mrs Rout, 48, said: "Thankfully it wasn't dangerous, but it's still causing problems. It's got everywhere – it was all over the kitchen floor and has found it's way into our dining room carpet. The trouble is, when you put water on it, it spreads like a dye. Not long after opening the letter I started to get a sore throat and it also got up my nose.
"I was worried about what it might have been, so I called the police."
Mr Rout, 49, added: "As a coastguard, I'm used to dealing with emergencies, but not at home.
"We've never had anything like this happen before. We don't know where the card came from or why it was sent.
"The response from the emergency services was brilliant, but we didn't expect that many. Our 13-year-old son Joseph was in his element with all the blue lights flashing in our street.
"It was a bit surreal having people coming into the house dressed in bio-suits, but fortunately it didn't turn out to be dangerous."
Anyone who knows who sent the card should call police on 101.
Force spokesman Mr Dunscombe added: "Those people who were inconvenienced by the closure are thanked for the patience."
