A new study on asthma has found children living in regional areas are less likely to develop asthma than those living in cities.

Professor Peter Sly from the Queensland Children's Medical Research Institute says the results indicate children should be exposed to different bacteria at an early age, and should spend more time outdoors.

"Exposure to bacterial products, particularly from animals and farming-related activities, helps educate the immune system as to what to ignore in the environment and that helps to protect the development of allergies and asthma, whereas in the city, kids don't get quite the same sort of bacterial exposures," he said.

However, Dr Sly says the findings are not an indication that all country areas are necessarily healthier places to live.

"It's not just simply having a country postcode that does it. It is the exposure from the environment."

"If you live in a big town in the country, you're going to be more like a child living in a big city than a child living out on a farm," he said.

The study, published in the New England Journal of Medicine, measured the level of bacteria and fungi taken from dust in children's bedrooms.