With today's tightly sealed, well insulated homes, the air inside your home can be two to five times more polluted than the air outside.
According to the book Lincoln the Unknown, Lincoln chose to spend several months of the year practicing law on a circuit that kept him living separately from his wife.
In 1928, a prominent writer had pointed to a close male friend of the young Lincoln as a possible lover that was denounced as absurd at the time.
Lincoln is believed to have suffered something approaching clinical depression.
In Lincoln's Preparation for Greatness: The Illinois Legislative Years, Paul Simon has a chapter covering the period, which Lincoln later referred to as "The Fatal First", or January 1, 1841.
Baker writes that there are "almost no gynecological conditions resulting from childbirth" other than a prolapsed uterus (which would have produced other noticeable effects on Mrs.
Lincoln) that would have prevented intercourse, and in the 1850s, "many middle-class couples slept in separate bedrooms." Far from abstaining from sex, Baker suggests that the Lincolns were part of a new development in America of smaller families; the birth rate declined from seven births to a family in 1800 to around 4 per family by 1850.
Attention to the sexuality of public figures has been heightened since the gay rights movement of the later 20th century.
In his 1926 biography of Lincoln, Carl Sandburg alluded to the early relationship of Lincoln and his friend Joshua Fry Speed as having "a streak of lavender, and spots soft as May violets".
Baker notes that "most observers of the Lincoln marriage have been impressed with their sexuality".
Some "male historians" suggest that the Lincolns' sex life ended either in 1853 after their son Tad's difficult birth or in 1856 when they moved into a bigger house, but have no evidence for their speculations.
The incident was not fully documented, but Lincoln did become unusually depressed, which showed in his appearance, and Simon wrote that "it was traceable to Mary Todd".