Minerva Mendoza lived in her tiny East Harlem apartment for 18 years. But for the last few months, she’s been afraid to go back to her home. Minerva Mendoza The blast happened less than 20 minutes after a neighbor called to report a gas smell. According to the National Transportation Safety Board, which is still investigating the explosion, a 125-year-old gas main running under Park Avenue was leaking near the buildings that exploded. The spark that started the blaze remains a mystery. But it cast a spotlight on the labyrinth of aging pipes carrying gas not only under New York, but cities throughout the country. Older cities on the East Coast, like New York, Boston and Philadelphia, are especially vulnerable, as they were built on cast-iron vintage pipe. While 2.5 percent of mains in America are cast iron, they account for 10.5 percent of incidents, according to the U.S. […]