Q The Housing Association I belong to is forcing me to install PVC windows in my flat. As an asthmatic, the quality of the air I breathe is of great importance, and I am very concerned about the dangers of PVC. - MF, London

A PVC - polyvinyl chloride; ‘vinyl’ for short - is among the most commonly used plastics in the world today, found in anything from toys to computers. It is also potentially one of the most hazardous plastics around. PVC’s major problems are at the beginning and end of its life. During manufacture, its basic constituents, such as ethylene dichloride and vinyl chloride, are released as gases into the atmosphere. They are carcinogenic, and can also cause liver, kidney and nerve damage.

Worse still, when PVC is disposed of - say, by incineration - it releases dioxin, one of the world’s most toxic substances.

Of course, your immediate concern is for your own personal health, and you are right to be concerned.

The major selling point of PVC window frames is that they are ‘maintenance free’. But ultraviolet radiation from the sun causes it to eventually become brittle and powdery. As it degrades, PVC emits toxic gases, such as vinyl chloride, some of which inevitably enters the home.

PVC also contains a wide range of toxic additives, in particular, heavy-metal stabilisers, fungicides and ‘plasticisers’. Plasticisers are phthalates, which are now believed to contribute to the off-gassing problem, and contribute to vinyl’s characteristic smell. Most phthalates are used to soften PVC, but some are added as hardeners to prevent the PVC becoming brittle - for example, as window frames.

Animal studies show that phthalates are as toxic as PVC itself, causing cancer, thyroid and kidney diseases, possibly due to their effects on the endocrine system. Being fat-soluble, they also tend to accumulate in the body. Steps have already been taken to ban phthalates from plastic nipples on baby-bottles, children’s toys and plastic tubing for hospital use. And wider prohibitions cannot be far behind.

A Danish-Swedish team recently studied over 10,000 children and found that phthalates may be a major factor behind the dramatic increase in childhood asthma and allergy. They found that asthmatic children lived in homes with the highest concentrations of phthalates in the house dust (Environ Health Perspect, 2004; online 15 July).

In 1995, Sweden banned all PVC products, and Denmark has imposed a tax on all PVC products and phthalates. Over 150 communities in Europe have already banned PVC or have policies to phase out its use in public buildings.

Are there alternatives to PVC windows? Yes, traditional wooden ones. Modern, high-performance timbers need minimal maintenance and claim a 50-year lifespan vs PVC’s maximum of 20-25 years. (Once promoted as an everlasting product with a ‘lifetime warranty’, PVC’s faster-than-expected deterioration means that even more toxic gases are produced than originally anticipated.)

Furthermore, wooden windows can be repaired after 50 years whereas PVC windows need to be completely replaced every generation.

Wooden windows have a lower initial cost than PVC, and don’t need to be replaced as often as PVC. In your case, it might be an idea to show this article (particularly the Danish research) to your local housing administration. If they won’t budge, it may be time to move.