The Met Office believes easterly winds could be carrying the smells
A foul smell detected in parts of England and Wales is being blamed on easterly winds bringing farming or industrial smells across the Channel.
Labelled "Euro-whiff" by the Met Office, the source of the smell - alternately described as sulphur and manure - is under investigation.
The Met Office said it had had hundreds of calls from the public looking for information about the odour.
The BBC News website has received more than 1,000 e-mails about the smell.
Readers have reported a range of sulphur and manure-like smells hanging over large parts of England and Wales.
The Met Office's Sarah Holland said: "Basically, over the last few days, we've had fresh, strong winds from an easterly direction. As a result some of our air is coming from continental Europe."
People sniffing the 'Euro-whiff'
She added that while members of Met Office staff were trying to trace the exact source of the "apparent atmospheric aroma", the likely explanation was either agricultural or industrial works in western Europe.
"Normally, our winds are westerly, coming off the Atlantic Ocean, which bring little or no pollution with them."
Forecasters say the easterly winds, which are bringing the current cold front in addition to the bad smell, are expected to last two or three more days.
BBC News website reader Sriram from Stevenage wrote that he feared there might be a dead animal near his house.
"I thought there was something that was dead, like a rat or a cat, and it was their decay that was causing the smell," he said. "I quickly got into the car and drove off, then at the station I parked the car and got out and the stench was still there. I had a serious scare now."
Marian Miller from High Wycombe, Buckinghamshire, said the smell had induced nausea.
"I noticed an acrid smell rather like burning plastic during the night, about 5am. It is the sort of smell you can taste."
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Matt from Cardiff said his first thought was to blame the neighbourhood pets.
"I thought it was our local neighbourhood dogs and cats being busy in the night in our garden - but the smell stayed noticeable during my three-mile bike ride to work."
Stu Maddison of Ealing, west London, said he noticed the stench as soon as he stepped out the door this morning.
Mr Maddison said the smell was still in the air when he arrived for work in Notting Hill.
"It's a bit rude really," he said of the air. "Various colleagues thought they'd trod in something but no, it's the air."
My wife and I live in Clapham and we noticed a smell this morning and thought it was from a fox. When I returned to the house a while later, the smell was still there and was all down the road. This afternoon it seems to have died down.
I've noticed a sickly sweet off smell, similar to silage, occasionally over the past couple of weeks. When we had the same smell a couple of years ago, which lasted for two weeks, it was blamed on a local sewage problem.
When I went to work this morning I thought that a farmer had been spraying his fields with manure. It was so strong it made me choke. The smell followed me all the way to Windsor. Lunchtime (1.00 pm) the smell seems to have dissipated somewhat.
For the last couple of days when i've gone out into the garden there has been this foul, strong smell in the air. As if 100 foxes have poo'd in the back garden. Now i know where the smell is coming from, doesn't make it smell any nicer though.
I went outside this morning at 8.30am with my daughter and we both smelt a disgusting manure smell. We thought our neighbour had been putting manure on his garden and blamed him! It reminded me of when I used to live in the country and didn't mind it too much but not every day!!!
In the last few days I'd noticed a tremendous stink on the A358 when motorbiking between Ilminster and Taunton. I was finding it hard to attribute it to any specific field as it seems to cover a very long stretch of the road.
I noticed what I thought was the smell of gas this morning when I left the house for work. I could also smell it in the car park at work. Other people here have been saying that they could smell sulphur in the air.
I was aware of an agricultural type smell in the air outside my home in Newport first thing this morning and thought it strange that the same smell was evident when I arrived for a meeting at the University Hospital of Wales, Cardiff at 9am.
When I went into the kitchen first thing, I thought it was gas I could smell. I checked the cats' litter tray - nothing there. On leaving for work I realised the niff was on the wind. So this is what it is!
In Norwich first thing this morning the smell was obvious and quite awful. As the wind picked up it appeared to clear slightly. Do remember that any pollution, emissions from agriculture and other "aromas" from the UK are usually blown across to Europe, so it's only fair we're suffering for once!
There has been a terrible smell in the air here for the past couple of days. Many people have commented on it. Smells like a mixture of sick & dung. All the kids were commenting on it coming out of school yesterday.
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