By Joseph PicardSPARTA — Monday marks the 16th anniversary of the 9/11 terrorist attacks on the U.S. Joan Costello of Sparta will be one of many to mark that day with sorrow. She lost her son, FDNY Battalion Chief James N. Costello, to the 9/11 attacks, even though he died 14 years later."Jimmy died on Nov. 25, 2015," Joan Costello said. "The FDNY deemed his death 'In the line of duty.' He was 52."The terrorist attacks involved four hijacked U.S. airliners. Two were flown into the twin towers of the World Trade Center in lower Manhattan, one was flown into the Pentagon in Arlington, Virginia, and the fourth, intended for Washington, D.C., crashed instead in a field near Shanksville, Pennsylvania after heroic passengers foiled the hijackers' plans. The attacks killed 2,996 people. In New York City, 343 firefighters and 72 police officers were killed. But many survivors and first responders have died since, due to illnesses contracted from toxic fumes at Ground Zero in New York City.According to reports, over 5,000 9/11 first responders have been diagnosed with World Trade center-linked cancers. Congress, earlier this year, put the number of first responders and survivors living with illnesses or injuries due to 9/11 at over 33,000.According to the FDNY, the total for New York firefighters killed by post-9/11 diseases contracted at Ground Zero is currently 159. James Costello, whose name was inscribed on the fire department's Memorial Wall last year, is one of them."Jimmy's death is considered a 9/11-related death because his illness, involving pancreatic and neuroendocrine cancers, was caused by his time 'on the pile' at Ground Zero," his mother said.On Sept. 18, 2001, then FDNY Captain James Costello led his men onto the Ground Zero pile in the first Task Force Recovery Operation there. The crew remained on this assignment for a month."He did not become sick right away," Joan Costello said. "Years later he developed health problems."Her son, like many others at Ground Zero in the days and weeks following the attacks, knew the air quality was not healthy but dutifully went about his work."How could you not know the air was bad?" Joan Costello said. "People were having a hard time staying there ten minutes, let alone all day and every day for weeks."She added: "Of the 343 New York firefighters killed on 9/11, Jimmy knew 150 of them."James Costello came to Sparta at age 7. He attended Rev. Brown Elementary School and Pope John XXIII High School, where he wrestled and played football. He went on to Fairfield University.In 1987, he joined the FDNY and moved to Manhattan. He was assigned to Engine 54, Ladder 4 in mid-town, the same firehouse his father served from until retirement in 1983. Fifteen firefighters from this firehouse died on 9/11. Costello was made battalion chief in 2003 and in that capacity, he was assigned to write the department's World Trade Center Report."It was an agonizing assignment for him," his mother said.He retired in June 2014 and was dead less than 18 months later."His wake and funeral were attended by hundreds of firefighters," Joan Costello said. "The FDNY sent a pumper truck and a fire engine that was emblazoned with his name and held his casket."Last year, Costello's name was entered on the electronic scroll at the 9/11 Memorial and Museum in lower Manhattan, as well as on the FDNY Memorial Wall in Brooklyn. Also in 2016, his name was entered on the National Monument to Fallen Firefighters in Colorado Springs, Colorado.This year, on Oct. 10, Joan Costello will travel to Albany, NY, as the guest of the federal Department of Homeland Security, to witness her son's name installed on the New York State Fallen Firefighters Memorial."Jimmy was a lover of people," his mother said. "He would say, 'There are no strangers — only friends we haven't made yet.'"