New Delhi, July 4 -- Eileen Castle's swimming pool, one of the only ones for blocks around, was once a refuge for neighborhood children on hot summer days.

But even as temperatures soared this week, Castle, 82, said she won't be filling the pool - not with the data center behind her house buzzing with the sound of its industrial air conditioners and its backup diesel generators belching fumes at unexpected times.

"I think about the air quality, the water, what effects it has on the kids in the area," she said on her front stoop as children whirred past on bicycles.

Hot weather of the kind sweeping the eastern U.S. drives up electricity demand for data centers, adding to their strain on power grids and worsening air quality for surround...