肺主气指的是肺主呼吸之气与一身之气。肺主呼吸之气，是指肺是人体的呼吸器官，主司人体呼吸运动。肺主呼吸之气的功能，实际上是肺主宣发肃降作用在呼吸运动中的具体表现。通过肺的宣发，浊气得以呼出，为吸入清气创造条件；通过肺的肃降，使肺能充分吸入自然界的清气。肺主一身之气，是指肺有主持并调节一身之气的生成和运行的作用，主要体现在两个方面：一是直接参与气的生成；二是调节全身气机。肺的宣发与肃降功能协调有序，则呼吸调匀，气息平和。
The term means that the lung governs respiratory qi and qi in the whole body. The lung governing respiratory qi means that the lung is the respiratory organ of the body and it governs respiration, which is the manifestation of lung’s functions of dispersion, depuration, and descent in respiration. Through the lung’s function of dispersion, turbid qi is exhaled, which makes inhalation of fresh air possible. Via its functions of depuration and descent, the lung can deeply inhale the fresh air in nature. The lung governing qi in the whole body means that the lung governs and regulates the generation and movement of qi in the whole body. If the dispersion, depuration, and descent functions of the lung are in harmony, breathing will be regular, rhythmic, and harmonized.
引例Citations:
◎肺主气，气之所行循经络荣脏腑。（《诸病源候论·风气候》）
（肺主气，气的运行循经络而营养脏腑。）
The lung governs qi, and qi moves along the meridians and collaterals and nourishes zang-fu organs. (Treatise on the Origins and Manifestations of Various Diseases)
◎脾虚则肺无所养，肺主气，故少气也。（《素问·脉要精微论》王冰注）
（脾虚就会使肺失水谷精气的滋养，肺主气，所以出现少气。）
Spleen deficiency results in a lack of nourishment for the lung from nutrients of food and drinks. As the lung governs qi, this in turn leads to weak breathing. (Plain Conversation Annotated by Wang Bing)