Research Institute
Home | Directions | Contact Us
Biogenics Research Institute
Other Respiratory Tract Disorders
Hypersensitivity Pneumonitis
Idiopathic Intersitial Lung Disease

Environmental Avoidance-Challenge Techniques

Environmental challenges may be done when the most likely causative environment has been identified. Challenges may be conducted in a number of methods depending upon the situation of the patient at the time. Many of these challenges may take weeks to complete. Below are likely situations that will be discussed:


A. The patient, an acute presenter, has been started on short-term systemic steroids by the referring physician and is stable with normal chest x-ray, pulmonary functions, and inflammatory markers of WBC, sedimentation rate, and C-reactive protein.


  1. Obtain base-line data and restrict the patient to the home environment (avoid the workplace).
    (Base-line data include chest x-ray, forced vital capacity, WBC, sed rate, C-reactive protein, and gravity air culture of the home)
  2. Quickly taper off systemic steroids to demonstrate the disease will reflare within a single environment.
  3. Move the patient from the environment as symptoms and objective measurements become abnormal.
    a) If symptoms and signs are mild to moderate, one may elect to monitor and not treat with steroids.
    b) If symptoms and signs are severe and intense, one may treat with systemic steroids to stabilize the patients symptoms and abnormal inflammatory markers.
  4. Keep out of the environment after stabilization and after tapering steroids. Monitor over a time period twice the length of time required to trigger the response described in #2 above. If signs and symptoms do not reflare, this is good evidence that the avoided environment is causative. If there is doubt, re-introduce the patient to the suspected environment, similar symptoms and response of inflammatory markers should recur in a similar time period.
  5. Remediation of the causative environment is carried out. The gravity air culture is repeated.
  6. When all remediation efforts are completed, introduce the patient back into the environment. Monitor at weekly intervals for evidence of reflare of signs, symptoms and inflammatory markers that may be less intense and in a longer time period than previously seen.
  7. If symptoms, signs, and inflammatory markers reflare, remediation has not been effective and other efforts must be initiated to determine the causative remaining site of contamination.


COMMENT: These patients usually can normalize when seen in early stages of acute inflammation before any significant fibrosis has occurred. They are the easiest to work with because the intensity of symptoms leads to early recognition that the disorder has re-flared. Exacerbations may occur in the same environment, or may occur in other environments with an identical contamination. Other environments that lead to flares must be identified and avoided. A short course of prednisone, or simply following the patient to confirm that symptoms and inflammatory markers resolve, are effective measures.

Return to top


B. The patient, a subacute presenter, housewife, has been fully evaluated and not started on any steroid treatment. Inflammatory markers including the sed rate and C-reactive protein are markedly elevated. Chest x-ray and the forced vital capacity are abnormal. The environmental history concerns only the home and suggests that the air conditioning system is contaminated.

Baseline data is available.

Move the patient into another dwelling. Since this patient may already have some irreversible changes, one should treat with systemic steroids until inflammatory markers are normalized and the FVC shows no improvement from the prior week.
While the patient is outside the home, an investigation by an air conditioning contractor is done to reveal the source in the air conditioning plenum and proximal ducts. The home is cultured.

The A/C system, including plenum, ducts, register boxes, and registers are replaced. The home is professionally cleaned and, then, cultured. Global anti-microbial prophylaxis measures are instituted.

The patient is returned into the home and monitored at weekly intervals for 4 weeks and then monthly for 3 months. If no exacerbation of signs, symptoms, or inflammatory markers occur, remediation has been effective.

COMMENT: This is the easiest type of environmental challenge. If there is doubt on the part of the patient
and concern about expenses for remediation, a challenge back into the home after moving and stabilizing with prednisone should be done to confirm that the disease will exacerbate in the home. This will usually convince the patient that the home does cause the disease.


C. The patient presented with shortness of breath with activity and a slight, non-productive cough that had been progressively worsening over the past year. A chest x-ray showed diffuse fibrosis. The FVC was 60% of predicted and diffusion was 45%. Inflammatory markers including WBC, sed rate, C-reactive protein, immunoglobulins, and serum precipitins were normal or negative. Open lung biopsy revealed end-stage lung disease. The environmental history revealed that a year before onset of symptoms a plumbing flood from a broken toilet tank connection that had affected most of the home. Carpets were not removed but simply dried in place.

COMMENT: Insidious onset or other patients that have advanced to end-stage lung disease cannot be evaluated by challenge techniques as above. There are no objective measurements that will respond in a reasonable time period. Investigation and culture of the home should be done. The patient should be moved from the home during remediation efforts. The home should be re-cultured before moving the patient back.
These patients must be followed long-term to determine if the FVC and diffusion has been placed in a non-progressive state. Medication should be tapered. Many of these patients can become non-progressive. Unfortunately, damage is usually so extensive that right-sided heart failure is likely because of pulmonary hypertension.