Kent-based charity Allergy UK has maintained the value of allowing children to play outside, in response to new research suggesting it has no impact on whether children develop asthma or other allergies.
Muriel Simmons, chief executive of Allergy UK, said children who spend most of their time indoors are more at risk of getting allergies "because their immune system hasn't been challenged in any way".
She added that "the healthier you are, the more exercise you can get, that's all going to help with the immune system".
Other factors such as pollution and living with smokers can also contribute to children developing health problems, noted Ms Simmons: "It's virtually impossible now to be chemical free, but it is pretty important not to be bombarded with chemicals."
Her comments follow the release of new research by the American Thoraic Society, which found exposing youngsters to infection does not protect them against allergies.
The researchers' findings challenge a long-held faith in the 'hygiene hypothesis', which suggests being exposed to allergens helps to strengthen children's immune systems.
Written by Tim Colman