Physicians have clearly stated that once the source of these allergies is removed or drastically reduced there will be a noticeable improvement in your overall health.

Studies have shown that environmental control is a key element to the management and treatment of asthma and allergies.

Here are some examples from medical journals which express the importance of allergen avoidance and environmental control.

“Mite population and allergen levels decreased by 90% or more within a month of placing mattress and pillow covers and treating bedding.”
Eggleston MD, P. "Clinical Trials of Allergen Avoidance in Established Asthma." Journal of Allergy and Clinical Immunology. November 2001.

“Encasing of mattresses and pillows resulted in a significant long-term reduction in allergen concentrations in mattresses and in the need for inhaled steroids in children with asthma and House dust mite allergy.”
“Effect of mattress and pillow encasings on children with asthma and house dust mite allergy.” Journal of Allergy and Clinical Immunology. 2003 Jul;112(1):220; author reply 220-1.

“In addition to genetic factors, exposure in early childhood to house-dust mite allergens is an important determinant of the subsequent development of asthma.”
“Exposure to house-dust mite allergen (Der p I) and the development of asthma in childhood. A prospective study” The New England Journal Of Medecine. 1990 Aug, Volume 323:502-507, Number 8. R Sporik, ST Holgate, TA Platts-Mills, and JJ Cogswel