The authors report a case of pneumonitis caused by methylene chloride (MC).

The patient was examined and diagnosed by clinical, radiologic, laboratorial and medical evaluation. The concentration of MC in the factory was measured to determine the exposure level.

The patient had an infiltration in chest X-ray, which underwent rapid relief of radiological finding, respiratory acidosis and hypoxemia in arterial blood gas analysis, and a ground-glass opacity in high resolution computerized tomography. MC was the only exposed chemical compound in this case. The concentration of MC was 39.9 ppm in the factory.

We diagnosed this to be a case of pneumonitis by MC based on clinical laboratory findings, exposure history to MC and MC concentration in the factory.