The military smokescreen was introduced on this day in 1923 in a test off Cape Hatteras. Its purpose was to conceal ship and troop movements from enemy eyes. For land and sea battles it works great, but in your house firing up a fireplace after it's been sitting idle all summer can cause all sorts of unwanted problems. They range from red eyes and coughing to air pollution and carbon monoxide poisoning. So before you hold a match to any logs, be they natural wood or natural gas, look for smoke signals. The Chimney Safety Institute of America urges homeowners to check flues and dampers for tightness, blockage, debris and buildups. You can do it yourself or hire a chimney pro to make sure everything is free and clear. Otherwise you could be in for a military-quality smokescreen of your very own -- with explosive action and real live firemen. And that's the On The House tip for today.