To help them find out, the Karolinska Institute Medical University here in Stockholm, together with a range of heart and lung charities, are holding two special days at the capital's Central Station, where passers-by can test their lungs and find out if they have any lung problems, free of charge.
They can do that in two ways, either by simply blowing a balloon, or by using the more technical spirometry tests.
Esther Edlundh-Rose is external relations manager at the Centre for Allergy Research at Stockholm's Karolinska Institutet Medical University, one of the organisers of the event.
She says the free tests in the middle of Sweden's biggest train station are a good way of reaching people that otherwise might not bother to test the functioning of their lungs.
"We want to raise awareness of asthma and COPD, and the only way to diagnose these is to do a lung-function test," Esther Edlundh-Rose told Radio Sweden, "so part of this is a big screening exercise, can we find people that didn't know they were suffering from these diseases? And also to raise awareness."
Taking the spirometry test is easy, you just take a queue number and then enter one of the cubicles where one of the nurses is waiting for you. You then blow hard into a tube connected to a computer, which registers the air-flow and charts it on a graph. The nurse can then either give you an all-clear, or recomment you visit your doctor for further tests.
"This is the fifth time we are doing this", Esther Edlund-Rose adds, "and we've found that about 15 percent of the people that have come have abnormal values."