 To study 1 the ability of exhaled nitric oxide and inflammatory markers in exhaled breath condensate nitrite, nitrate, hydrogen peroxide, 8-isoprostane, interferon-γ, tumor necrosis factor-α, interleukin-2,-4,-5,-10, acidity to discriminate between childhood asthma and controls. 2 the ability of these biomarkers to indicate asthma severity and control. 