By JEFF AMYBy some measures, chemical plants like the sites of separate fatal explosions this week in Louisiana are among the safest manufacturing workplaces in America. That doesn't stop residents and emergency responders from keeping wary eyes on the hundreds of facilities stretched along the Mississippi River from New Orleans to Baton Rouge. Because of the volatile nature of many of the products they make, explosions, chemical releases and other accidents are real threats. Emergency officials say they're well-drilled to respond but residents do worry about what can happen next door. The threat was underscored Friday when a second fatal explosion occurred at a plant located just miles away from the site of the previous day's deadly blast. "For the most part, day to day, month to month, year to year, you don't really think about it," said Ascension Parish Councilman Travis Turner, who lives about 4 miles from the plant in Geismar where the earlier explosion occurred. "Everybody knows somebody â¿¿ a brother or cousin or uncle â¿¿ who works at a plant. When something happened, everybody is worried about the worst case scenario, like yesterday." State and local officials have welcomed oil refineries, chemical plants and related industries, with their heavy capital investments and good-paying jobs. Louisiana is experiencing a boom in new plants and expansions, driven by low natural gas prices, as well as the area's strategic advantages. Louisiana Economic Development counts more than $30 billion in investments announced in Louisiana starting in 2011, and that doesn't include a number of upgrades. Among them is a $400 million expansion at the Williams Companies Inc. plant where two workers were killed and dozens more were injured as a result of a Thursday explosion that was heard for miles. On Friday night, a separate, smaller explosion occurred miles away in Donaldsonville, killing one person and injuring seven others, the state police said. Workers were offloading nitrogen by hose from an 18-wheeler and pressurizing a metal "vessel" when it failed, causing the explosion at a CF Industries facility that makes ammonia and other nitrogen fertilizers, Sandifer said.