FEV1

Participants’ FEV1 levels were measured during a health exam. FEV1 is a measure of how much air is let out in the first second when a person forcefully exhales. Low FEV1 can be a sign of obstructive lung disease (difficulty exhaling). The FEV1 readings were categorized to describe the risk of obstructive lung disease from normal (no risk) to mild, moderate and severe risk of obstructive lung disease.

This chart shows responses from all individuals who have participated in each and every survey wave. It follows the same cohort of people over time.