Unusually smoggy Chicago weather set off thousands of newly-required home carbon monoxide detectors today, forcing city officials to plead for calm. The Fire Department responded to at least 2,000 calls in the past 24 hours from frightened residents who worried the alarms signaled high levels of the noxious, odorless gas. But forecasters attributed the phenomena to a "temperature inversion" that trapped several days' worth of smog in the area. Three months ago, Chicago became the first major city to require the devices. But today, fire officials criticized one of the largest manufacturers, First Alert Inc of suburban Aurora, for not being responsive to consumers' queries.