Ten subjects' eyes were exposed to formaldehyde at different doses ((0 mg/m~3,) 1 mg/m~3, 2 mg/m~3, 3 mg/m~3) for five minutes. The content of substance P in the nasal lavage were determined by radio immune assay (RIA). The results showed that the content of substance P increased after exposures, especially during the exposure of 3 mg/m~3 formaldehyde (p