Posted By Paul Leadbetter Bill Natural gas has no smell so Transco add something smelly so that we can detect any leaks. The substance added is a mercaptan - related to the substances that make cabbage smell. Is there anything in or near the building that is rotting and which could release the nasty smell? As an occupational hygienist, I could help you to track it down. Contact me off-list if you would like any help. Paul

Posted By Hilary Charlton Is there any heavy dirty transport going past your place overnight? I know a lot of smelly loads are shifted overnight to reduce the amount of discomfort during the day. It could be that fumes are getting stuck somewhere in your ducting and are only noticeable when the air conditioning is initially turned on but then go off after a while which is why when the engineers come in they can't find anything. Unlikely I know but possible. Hilary

Posted By Adrian Watson Dear Bill, Look at what is different. Exactly what is happening and when? What are the smells like? When did the smells start? Are they all year around? When is the high or low tide? Is there a solid floor or suspended floor? Do you have an old style drainage system? From the information that you have provided I surmise that: As the building is a converted Victorian building, it has a suspended ground floor; That there is either an earthen floor beneath the structural floor or that the sub floor area is contaminated with silt; That this area is wet or damp; That bacterial action is taking place in this material, which is producing the odours; That the tidal action and/or heating the building is producing a pressure differential that is allowing or forcing the gaseous products in the sub floor space to enter the building. This may be totally wrong, but it'll give you a starting point. Regards Adrian Watson.

Posted By Adrian Watson Dear Bill, The fact is any of these scenarios could be right, but most of them will be wrong! As I stated previously look at what does and does not occur. Check if your neighbours have a similar problem. If there are no complaints within the local neighbourhood, the source is unlikely to be external to other building, but it could be. Find out who is and who is not complaining. Are they male, female, old, young, manager, call operators, etc. What is and what is not different about who is making the complaints? Note that if you have not smelled the odour, that there could be no odour at all ... it could be a sign of other problems, or you could have visited at the wrong time! Has anybody taken a walk around the outside of the building when the event is taking place? If not do so, and especially in the area of the HVAC intakes. If there is no smell outside then it is unlikely to be an external pollutant. Is the smell stronger in some parts of the building, if so where? What is and what is not different about where it occurs? When does it occur? Does the event occur every day; does it occur at the same time; does it occur under the same weather conditions. What is and what is not different about when it occurs? Regards Adrian Watson

Posted By Eric Burt Any chance of the glue in the chipboard / MDF releasing formaldehyde? There was a case of this at Liverpool University some time ago I seem to remember. Or have you had any new carpets fitted (in terms of the glue smelling). Also - I remember an embarrasing incident which "happended to a friend of mine" where the Gas Board were called in to investigate a strong smell of gas and found a dead mouse trapped behind a central heating pipe. It gave off quite a whiff when the heating came on! Eric

Posted By Dave Wilson Before I got to stuart I was thinking Tidal river! Overnight, anaerobic activity, Eutrophication, drains, smell. Think Stuart may have it here! Ask the Environment Agency / Water Authority what the water quality of the river is and whether anyone upstream has an Authorisation/permit to discharge under IPC/IPPC as this is a 'controlled water'.

Posted By Dave Wilson Grade 2 building have you checked that the drainage vent pipes are not venting into the building as they may be too close to an A/C unit which is sucking the air into the building.

Posted By John Webster Had a similar problem with a refurbished old building which had been built on land that, up to a few centuries ago, had been tidal. The smell was noticeable in the mornings, but only when the night storage heating was turned on. The heaters therefore kept getting the blame. The smell was a bit like the one you get near an airport, partially combusted kerosine. I concluded that the old underground silt deposits had probably produced traces of oil (a natural process) which were slowly migrating upwards into the solum. Trapped by a heated building, with little ventilation at night, some vapour was then being drawn into the heaters by convection, producing the characteristic smell. Proof would have been more difficult, as the concentrations of hydrocarbon involved would be miniscule - way below any safety levels, and results easily distorted by traffic immediately outside the building. Once staff had accepted this plausible explanation, they were no longer concerned about the smell (which soon dispersed in the morning anyway). I don't doubt that improving underfloor ventilation would cure the problem, (although all we need do is leave a few windows open a crack). Refurbishment means we now tend to seal up and insulate old buildings which were once cold and draughty, and this often creates quite unforseen problems.

Posted By Bill Elliott Thanks to all who replied to this - you have given me a number of areas for further consideration. Have met with local EHO regarding the incidence of similar problems in adjacent premises which all appear unaffected. I am thinking along the lines of vents from WC's running inside the building at present - will keep you posted.