Asbestos is fibrous material used as insulation and as a fire retardant. It is a dangerous substance, the use of which is being phased out, but it still remains in many old buildings. Some asbestos release carcinogens when moved. It is best therefore, if you suspect you have exposed asbestos in your house, to contact your local council and let them deal with it safely.

Bleach acts by sterilising organic matter through oxidisation. When you chuck bleach down your toilet it not only kills bacteria in your loo (which is why you do it), but it continues to do this right down the sewage chain, killing bacteria which help break down sewage in processing plants. Eco-friendly alternatives use acids which dislodge the dirt, rather than oxidising it.

Cadmium is a rare, soft bluish-white metal, known to cause cancer. It is a common impurity in Zinc.

It is widely used in batteries, plastic products, and pigments, and is found in solder.

Inhalation results in chemical pneumonitis, pulmonary edema, and death.

Carbon Monoxide (CO) is a colourless, odourless gas that in high quantities causes death by affecting the body’s ability to transport oxygen. It is thought to contribute to the greenhouse effect. In any case, it is short lived, reacting to form carbon dioxide.

CO is produced as car emissions, and by household heating systems.

Avoid products containing perchloroethylene (carcinogen, and suspected to damage, liver, kidneys and nervous system), and ammonium hydroxide (corrosive irritant).

We have all had significant exposure to BFRs, brominated flame retardants, which are used to treat electronic equipment (including computers), foam furnishings, curtains, chair covers, and clothes as a result of legislation passed some 20 years ago.

Take care with formaldehyde resins, which can cause irritation, and in high doses are carcinogenic. Products using formaldehyde should adhere to WHO standard E1.

Formaldehyde is also found in small amounts in timber - wear a mask when sawing and sanding. It is produced as part of the human metabolic process, as well as from car exhausts and in tobacco smoke.

Avoid petroleum distillates (possibly carcinogenic), and products containing nitrobenzene (highly toxic).

Mercury is a rare, heavy, silver, metal which is found in liquid form at room temperature. It has many uses, including thermometers, cosmetics, batteries and dental amalgam. It is harmless in insoluble form, such as mercuric sulphide, but poisonous in soluble forms such as mercuric chloride. It can be absorbed through the skin and mucous membranes, as well as through inhalation. It affects the nervous system. Low level exposure can cause fatigue, memory loss, depression and tremors.

Nitrogen oxides are a group of chemicals that are a major cause of smog produced by car emissions. They react with sunlight to produce ground-level ozone. They form nitric acid when dissolved in water, contributing to acid rain. They are also a greenhouse gas.