New Zealand scientists have long been at the forefront of research into asthma, hayfever and eczema. In 1991 a group from the University of Auckland headed a study called the International Study of Asthma and Allergies in Childhood (ISAAC).

Now the same team, headed by Professor Innes Asher who works in the University's Faculty of Medical and Health Sciences, has updated its study.

The update, an abstract of which you can find here, shows that childhood allergies have become more widespread since 1991. The researchers studied children in developing countries, such as Brazil, India, Iran and South Africa and developed countries, such as Canada, New Zealand and the UK.

Results vary from place to place but there were some interesting general findings. Rates of asthma in older kids decreased from the 1991 study, but younger children were more likely to suffer from asthma this time around.

Eczema, on the other hand, has become more widespread among all children, and especially younger children. 

Hayfever rates rose among all age-groups

The study raises important public health and environmental considerations, especially in fast-growing places such as China and India, where booming economies are leading to big problems with air pollution.

--Simon Robinson/Johannesburg