Easy self-examination
Normally, a healthy adult should be able to hold his breath for more than a minute, but anything less than 10 seconds is a sign that lung capacity is really poor and there may be some lung problems or other medical problems.
Take a round, unblown balloon and blow hard into it until it's all gone. Look at how long it takes you to exhale, and how big the balloon is over time. A healthy adult should be able to vomit in about six seconds after taking a full breath. If it is less than six seconds, one of two things may happen. The first may be that when the lungs are full of air, there is too little air in the lungs. The second may be that the muscle strength is too bad, so that it can not vomit the gas clean and stops exhaling, so that the gas is trapped in the lungs. If the whole process takes longer than six seconds, the lungs may be a little blocked, so when you exhale, you can't get it out quickly
Another is to observe the balloon in the first seconds exhaling. The final balloon volume is 80%, because in the first second of hard exhalation, the gas exhaled by the subject should be about 80% of the maximum lung capacity, so we can observe the change of balloon volume in the first second of exhalation, to judge whether the lung function is normal.