What we casually refer to as smoker’s cough is actually a serious disease affecting around 800,000 Greeks – half of whom are unaware they suffer from it, the World Health Organization (WHO) said yesterday. Chronic Obstructive Pulmonary Disease (COPD) is the fourth leading cause of death worldwide, killing nearly 3 million people annually, WHO said ahead of World COPD Day tomorrow. In Greece, where half of adults smoke, 11.6 percent of men and 4.8 percent of women over 35 are believed to suffer from the disease. If the current trend is not bucked, COPD will become the third leading cause of death by 2020, WHO said. Smokers – active or passive – who fear they may suffer from COPD should undergo a respiratory function test. Experts will be offering free tests from 9 a.m. to 5 p.m. in Syntagma Square tomorrow.