An "awful" smell in Crumlin that residents have had to put up with for the past 30 years is being investigated by environmental experts.

Natural Resource Wales (NRW) said it is investigating a report of a "sulphur odour and water discolouration" in the area.

Locals have reported that the smell has lingered for years, with one man saying the stench has become a "running joke".

Robert Morgan, who works at Bullen Trading Co. Ltd in Crumlin, said: "We notice it every single day, 'the Crumlin Stink'. It is a sort of running joke. We just get on with it."

South Wales Argus:

Angela Drakeford, who owns music venue The Patriot Home of Rock, added: "It has always been here, it's normal for Crumlin. I cannot smell it inside my music venue, but when I drive through Crumlin at two or three in the morning it smells awful. 

"When I drop my staff off here, I say to them, I do not know how people live there in those houses - It's something else."

Tom Weston, who works at Beehive Photography Studios, said the problem "comes and goes".

He said: "We do notice it. It is sulphur from the old pit. I do notice it but it doesn't come inside the business. I notice it if I go to the west side of the town."

Residents have speculated that the "eggy" smell could be coming from the old colliery nearby or from the river.

South Wales Argus: Bill Davison, volunteer at The Friends of Crumlin NavigationBill Davison, volunteer at The Friends of Crumlin Navigation

Bill Davison, a volunteer at The Friends of Crumlin Navigation said: "There is an egg-like smell that emanates from the vegetation. At the bottom of the main shafts you have stagnant water running out and vegetation with chemical processes that rise up into the atmosphere.

"It is a natural process and doesn't pose a risk to health."

An office worker based in Crumlin who asked to not be named said: "I have never known it any different. I've been here nearly 30 years. I think my nose is immune to it but we have had new girls at work and they say it is bad.

"Sometimes we like to sit out the back for our lunch and if it has rained it is awful. I feel it is much more potent if it is raining and if there has been a dry day the drains can stink."

The exact cause of the "eggy" smell and its potential impact on health has not yet been confirmed, but a Caerphilly Council spokesperson, said: "We are aware of the concerns raised by the local community and have referred the matter to NRW to investigate."

Councillor Carl Thomas said: "As local ward members we are aware of the concerns raised by local people and we have asked the council's environmental health team to work with NRW to investigate."

Kirsty Lewis, senior environment officer for Natural Resources Wales said: "We are currently investigating a report of a sulphur odour and water discolouration in Crumlin.

“An environment officer met on site with the reporter to discuss their concerns and investigations are ongoing.

“We will continue to work in the area to identify the source and ensure all necessary steps are being taken to protect the local environment and its people."

The public can report environmental incidents 24 hours a day, seven days a week by calling Natural Resources Wales' incident communications hotline on 0300 065 3000 or filling their online form here.