Beware the property death trap

Whether you own and maintain a commercial property or a series of residential properties, there are a number of associated risks such as fire prevention, flood risks, theft etc. One of the risks less obvious to the eyes and ears are toxic gases. These can be caused by a number of factors including poor maintenance and failing to take responsibility for the well-being of your tenants through greater awareness of risk.

If a property remains unoccupied for a long period it can prove more difficult to detect when toxic build-ups have occurred. In order to keep building occupants or unoccupied structures safe from potentially deadly gases you must follow all monitoring procedures closely.

By learning about the hazards you can detect them quickly and take immediate action. Making an effort to protect against these gases will reduce liabilities and keep your properties in top condition.

Which are the main gases, and how can you recognise there’s a problem?

Carbon Monoxide

One of the most commonly known gases, yet potentially lethal, things to be aware of are:

  • It is colourless, odourless and extremely hazardous.
  • Produced by flames burning without adequate oxygen supply.
  • Main sources in commercial buildings and residential homes are leaks from flues, gas boilers or oil furnaces; and fireplaces.
  • Can be prevented with proper monitoring, maintenance and ventilation.
  • Symptoms of exposure include headache, dizziness, nausea and fatigue.
  • Serious exposure may cause unconsciousness or death.


Radon occurs naturally and many people are unaware that their property is situated in an area known to have high concentrations. It’s worth checking the postcode of the property to see if this is the case before purchasing if possible, otherwise details are as follows about the risks:

  • Radon is found in the ground, but may enter homes or other buildings through cracks in the foundation.
  • The effects can be reduced or eliminated with under-floor ventilation, a radon sump system or positive pressurisation/positive supply ventilation system. Use approved installers only.
  • It’s more difficult to notice its effects as the gas accumulates gradually over time.
  • Radon is however radioactive and could cause lung cancer when inhaled.

Nitrogen Dioxide (NO2)

Perhaps lesser known but dangerous nonetheless. And whilst the below are more obvious in higher concentrations causing these acute effects, lesser amounts are not as detectable but can cause lasting damage in the form of more chronic illnesses.

  • Sharp, biting odour and red-brown in colour, but only visible at very high concentrations.
  • Extremely toxic, but easily detected by smell.
  • Main sources are in the fumes coming from home heaters and gas stoves.
  • Symptoms of exposure include bronchitis, pneumonia and severe lung damage.

Sewage Gases

If you own properties that are left empty frequently this is more likely to be a hazard that you come across, regular visits to your property can help with early detection. Examples include:

  • Primarily methane gas, but also include mixtures of hydrogen sulphide, ammonia, carbon dioxide and sulphur dioxide.
  • Can enter buildings when plumbing fixtures are used infrequently, or if sewers or drains have become blocked for a period of time, so unoccupied properties are the biggest concern.
  • Can cause eye irritation, cough, and sore throat, shortness of breath, loss of appetite, headaches and dizziness.

To best combat these property risks it’s recommended you try to follow the below tips:

  • Firstly invest in Toxic Gas Detectors for all of your properties, and ensure they are installed in the most relevant areas, and maintained properly.
  • Be sure not to cover any ventilation such as air bricks when provided, they are there for a reason so keep them clear. Advise tenants to do the same, as many people think they are a source of drafts so block them up or board them over.
  • Give your tenants a simple handout which details symptoms to look for where possible gas exposures are possible. For example a person suffering from Carbon Monoxide poisoning would most likely be unusually extremely red in the face because the blood becomes oxygenated, they also might appear slightly drunk, therefore should be removed to fresh air immediately. This will usually occur prior to other symptoms listed above.
  • In regards to Radon, this can only be verified through a proper survey – usually this is a part of the conveyancing checks, especially if the property is in a specified radon area. A ground survey should always be included in any new build projects.

If you are unsure then you can always seek professional advice. Health and Safety officers can give you the benefit of their knowledge and steer you with the right course of action to best protect your tenants and properties. If you wish to speak to our Risk Management department with any concerns over Health & Safety or Employment Law matters then simply email jrm@jelfgroup.com.