But LEED — sponsored by the U.S. Green Building Council, an industry group — has a glaring and little-known drawback: It places scant emphasis on factors relating to human health, even as the largely unregulated use of potentially toxic building materials continues to expand. One of LEED’s major accomplishments — saving energy by making buildings more airtight — has had the paradoxical effect of more effectively trapping the gases emitted by the unprecedented number of chemicals used in today’s building materials and furnishings. Yet, as the threat from indoor air pollution grows, LEED puts almost no weight on human health factors in deciding whether a building meets its environmental and social goals.