The term 'IT CAN LEAVE YOU BREATHLESS' can be solved by two crossword solutions: ASTHMA (6 letters) and SMOG (4 letters). Asthma is a chronic lung disease that causes difficulty breathing, wheezing, coughing, and chest tightness. It is caused by inflammation of the airways, which can be triggered by allergens, irritants, or exercise. SMOG is a type of air pollution that is created when sunlight reacts with pollutants from cars, factories, and other sources. It is made up of a mixture of smoke, fog, and other particles, and can cause respiratory problems in people who are exposed to it.