Several months into the monitoring, officials from the plant voluntarily pledged to reduce airborne emissions of the chemical, chloroprene, by 85 percent, and they’ve begun a $17.5 million installation designed to accomplish that. But based on the monitoring results so far, environmentalists are saying the goal isn’t nearly ambitious enough. Even if Denka Performance Elastomer LLC achieves it, they say, the air for miles around still will contain levels of chloroprene that fa