[1][2] Possible causative agents include radiation therapy of the chest,[3] exposure to medications used during chemo-therapy, the inhalation of debris (e.g., animal dander), aspiration, herbicides or fluorocarbons and some systemic diseases.

Diagnosis of pneumonitis remains challenging,[7] but several different treatment paths (corticosteroids, oxygen therapy, avoidance) have seen success.

Diagnosis of Pneumonitis is often difficult as it depends on a high degree of clinical suspicion when evaluating a patient with a recent onset of a possible interstitial lung disease.

[7] Diagnostic procedures currently available include: Exposure to causative agents of pneumonitis in a specific environment can be confirmed through aero/microbiologic analysis to verify its presence.

[7] Clinical tests include chest radiography or (HRCT) which may show centrilobular nodular and ground-glass opacities with air-trapping in the middle and upper lobes of the lungs.

[7] Histological samples of lung tissue with pneumonitis include the presence of poorly formed granulomas or mononuclear cell infiltrates.

[13] Since pneumonitis manifests in all areas of the lungs, imaging such as chest x-rays and Computerized tomography (CT) scans are useful diagnostic tools.

During external examination, clubbing (swelling of fingertip tissue and increase in angle at the nail bed),[14] and basal crackles may be observed.

For hypersensitivity pneumonitis many diagnoses take place through the focus of blood test, chest x-rays, and depending on severity of infection doctors may recommend a bronchoscopy.

Inhaled corticosteroids such as fluticasone or budesonide may also be effective for reducing inflammation and preventing re-inflammation on a chronic level by suppressing inflammatory processes that may be triggered by environmental exposures such as allergens.