A new study suggests that children who live in tree-lined streets are less likely to develop asthma.

The study, based in New York City, was carried out by researchers at Columbia University and the results are published in the Journal of Epidemiology and Community Health.

Between 1980 and 2000, rates of asthma in the US have increased by a staggering 50%, with children in poor urban communities suffering most. In New York City, asthma is the leading cause of admission to hospital among children under 15.

Researchers say that children of women who eat a Mediterranean style diet during pregnancy are far less likely to develop asthma or allergies later in life.

The Greek researchers who conducted a study involving 468 pregnant women and their offspring published their results this week in the journal Thorax. They conclude that women who eat a diet characteristic of that found in Mediterranean countries which includes large amounts of fruits, vegetables, and fish, are greatly reducing the chances of their children developing atopic diseases.

Researchers have discovered a mechanism which can lead to asthma and allergies by interfering with the immune system raising hopes that a cure isn't far away.

The joint British and Swiss research effort has uncovered evidence that a specific gene can lead to a loss of regulation in the immune system that ultimately increases an individual's chances of developing asthma, hay fever and other allergies.

Researchers from Imperial College London, the Swiss Institute of Allergy and Asthma Research in Davos, Switzerland, and a number of other international institutions published the results of their study yesterday in the journal PLoS Biology.

A new study shows that children who regularly breathe in second-hand smoke as infants are almost twice as likely to develop allergies.

The findings come from research headed by the Institute of Environmental Medicine, in Stockholm, Sweden, which involved more than 4000 families.

Parents were interviewed about their children's allergies and asked to fill in questionnaires when their child was aged two months, 12 months, two years and four years.

The questionnaires included questions about various environmental factors to which the children had been exposed before and after birth. These factors included cigarette smoke, pet dander (animal hair and dead skin) and certain foods with high allergenic potential such as wheat, cow's milk and peanuts.

Information on other factors that can affect allergy incidence was also gathered. Data on the outdoor air pollution the children were exposed to was extrapolated from levels of vehicle and industry pollutants known to be present where each child lived. Socioeconomic factors were also taken into account with parents asked to complete employment and education histories. In addition the parents were asked about their own history of allergic diseases.