Responses to long-term low dose

Most of the symptoms produced by phosgene poisoning occur as a consequence of damage to the lung and its associated structures. Man s respiratory system is highly specialized for gas exchange in air. The internal surfaces of the system are brought into contact with the air via the respiratory tract and the operation of a tidal ventilation mechanism (see Fig. 2.1). 

During inspiration, air is drawn into the lungs via the nose and/or mouth, travels along the trachea and into the bronchi. It is then dispersed throughout the bronchioles to the 

A diagram of the human respiratory apparatus and associated structures. 

Phosgene has a relatively low solubility in water and consequently is able to penetrate to the terminal bronchioles and alveoli where it reacts chemically with cellular and 

Eventually, sufficient fluid collects to seriously inhibit gas exchange. Consequently, anoxemia occurs and blue cyanosis is evident. The patient s breathing becomes increasingly dyspnoeic.t and the now frothy, protein-rich oedema fluid emerges in the upper respiratory tract. The viscosity of the blood increases because of lost plasma, and it becomes brown due to the formation of methaemoglobin. These circulatory disorders may further compromise oxygen uptake, and the blue cyanosis may become grey. 

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