The evils of New York’s tenement houses as observed in 1900 were summed up as follows:Inefficiency of light and air due to narrow courts or air shafts, undue height, and to the occupation by the building or by the adjacent buildings of too great proportion of the lot area; danger from fire; lack of separate water-closet and washing facilities; overcrowding; foul cellars and courts and other like evils, which may be classed as bad housekeeping (p. xiv).
The presence of a shop in a tenement house adds three elements of danger during an epidemic. It gathers together men, woman, and children from other tenements where the disease may be, and instead of keeping them by themselves in large, light factory rooms, the tenement house shop throws them into direct contact with tenants living in the worst and most unwholesome houses. (p. 42)