Men with low vitamin D levels are more likely to suffer heart attacks than men with healthy levels of the vitamin, according to a study released this week.

By PBS News Hour

Just one week after the Bush administration announced its first new ozone standards in more than a decade, chemists have discovered that a chemical reaction in the atmosphere once thought to be insignificant may be a major contributor to smog.

By PBS News Hour

Daylight saving time, which usually begins the first week of April, will be start earlier by four weeks starting this year, due to federal legislation passed in 2005. Two authors examine the impact of advancing the start of daylight saving…