One-third of those killed are children
According to the World Health Organization, passive smoking causes 600,000 deaths each year—one-third of them among children, who are often exposed to smoke at home. The WHO study looked at 192 countries, and found that passive smoking is especially bad for children, putting them at higher risk of sudden infant death syndrome, pneumonia and asthma, Reuters reports. It also causes heart disease, respiratory illness and lung cancer. The lungs of kids who breathe in secondhand smoke might also develop more slowly than those of kids who grow up in smoke-free homes.