The kind of gas we mean isn’t the type that feeds your boiler or hob – we would hope that any half-competent builder has established the route of the gas main and other services before they put a shovel to the ground. Nor is it the kind that miners fear; you’d have to go much deeper for that.
But there are many kinds of gas. Gases are given off by numerous chemicals and materials used in modern building construction, and by modern interior finishes and soft furnishings. Gases are also given off by the construction machinery used in your build and by the domestic appliances you’ll be running once your basement is in use. Believe it or not, gases are also given off by human beings – by breathing (mostly).
Hazards fall into two main categories: those that occur during construction, and those that might affect the occupants in years to come.
Gardeners working in the open air have been fatally overcome by toxic fumes from the flowerbeds of certain plants. It’s not a common event but it happens. Chemicals often encountered by builders cause tragedies considerably more often. Although most are aware that chemicals they use might give off fumes, the gases are invisible so it is hard to assess how they move – whether they are blowing away or building up. They can gain a hold surprisingly suddenly.
Recently a young worker cleaning paint from brickwork in the basement of a £5 million property near Notting Hill Gate Tube was overcome by chemical fumes and died before he could be retrieved from the building. Paramedics were forced back by the fumes and had to wait for fire brigade personnel in breathing apparatus to retrieve the man before they could attempt CPR.
The fumes are believed to have come from a single spray canister of an unusually noxious solvent, but adhesives, timber treatments and paint thinners can all pose dangers in confined spaces.
A more common cause of concern is carbon monoxide. Responsible builders will not use a petrol driven compressor inside a basement, but propane space heaters, bitumen melting posts, cut-off saws, and blocked boiler flues still occasionally cause serious mishaps. Around 50 people die in the UK each year from the effects of carbon monoxide.
A hazard of which most home owners are still less aware is that posed by commonplace home cladding, artificial flooring, and soft furnishings. Plastics, adhesives and other chemicals in many carpets, curtains, furniture and floor tiles emit a family of chemicals known as volatile organic chemicals, or V.O.C.s. Research into the extent of the long term danger they pose is still ongoing, but they are best avoided in bedrooms, living rooms, and wherever small children play.
These VOCs are in so many modern fabrics and household items that avoiding them completely is impossible; however, anyone contemplating a new basement construction in London should bear the dangers in mind when choosing final finishes and furnishings. A specialist basement construction company will be able to provide you with expert advice about air conditioning and filtering systems and help you choose the healthiest materials for your new space.