Japan's Meteorological Agency says that the extensive forest fires of Indonesia are hastening the process of global warming by increasing ozone levels in the atmosphere. A study conducted by the Agency's research institute at Tsukuba, east of Tokyo, sampled and measured greenhouse gases (GHG) emitted by the massive fires using collectors on Japan Airlines planes on the Tokyo-Sydney route since 1993. When the fires were at their peak during 1997 and 1998, scientists found that the carbon monoxide (CO) content in the air rose to 380 parts per billion - which was ten times the normal level. CO is especially dangerous because it produces ozone through a complicated photo-chemical reaction. The planes also collected samples of other GHGs, including carbon dioxide and methane, but the rise was most significant for CO. The forest fires caused by slash-and-burn methods of agriculture contribute even more to global warming than previously believed.