Double chamber plethysmography is a well established non-invasive method of assessing airflow obstruction in small lab animals. It allows measurement of the specific airway resistance (sRaw), which unlike Penh, is a meaningful airway mechanics parameter. Since sRaw is measured in spontaneously breathing mice, a limitation of the method is the inability to exclude nasal resistance changes. We have recently shown that mice are not truly obligate nasal breathers, and that after nasal occlusion, nasally breathing mice can transition to an oral mode of breathing. We now show that it is experimentally possible to algebraically separate the average nasal and pulmonary (including laryngeal) components of total airway resistance change, by a series of measurements made across groups of mice breathing nasally or orally, assuming that oral resistance and lung volumes remain constant. Utilizing this approach, we show that nasal resistance change comprises half or more of the total resistance change during methacholine challenge. Inhibition of mucin secretion from airway goblet cells, attenuates pulmonary but not nasal airway hyperresponsiveness (AHR), and that nasal AHR in a murine model of rhinitis may be related to edema.