甲醛有刺激性气味，低浓度即可嗅到，人对甲醛的嗅觉阈通常是0.06-0.07mg/m3。但有较大的个体差异性，有人可达2.66mg/m3。长期、低浓度接触甲醛会引起头痛、头晕、乏力、感觉障碍、免疫力降低，并可出现瞌睡、记忆力减退或神经衰弱、精神抑郁；慢性中毒对呼吸系统的危害也是巨大的，长期接触甲醛可引发呼吸功能障碍和肝中毒性病变，表现为肝细胞损伤、肝辐射能异常等。
Formaldehyde has a pungent odor, which can be smelled at low concentration. The olfactory threshold of formaldehyde is usually 0.06-0.07mg/m3. However, there is a large individual difference, some people can reach 2.66mg/m3. Long term and low concentration exposure to formaldehyde can cause headache, dizziness, fatigue, sensory disturbance, reduced immunity, drowsiness, memory loss, neurasthenia and mental depression; chronic poisoning also has great harm to respiratory system, and long-term exposure to formaldehyde can cause respiratory dysfunction and liver toxic lesions, manifested as liver cell damage and abnormal liver radiation energy.