The most serious adverse effect of the window tax was on human health. A series of studies by physicians and others found that the unsanitary conditions resulting from the lack of proper ventilation and fresh air encouraged the propagation of numerous diseases such as dysentery, gangrene, and typhus. In one instance in 1781, a typhus epidemic killed many citizens in Carlisle. Dr. John Heysham traced the origins of the outbreak to a house inhabited by six poor families...and described the dwelling in this way:For a century and a half houses in England and Scotland were taxed by the number of windows they had. Naturally, the citizens subject to the tax responded to the incentive and minimized the number of windows. Even bricking up windows that had once existed in dwellings and shops.
In order to reduce the window tax, every window than even poverty could dispense with was built up, and all source of ventilation were thus removed. The smell in this house was overpowering, and offensive to an unbearable extent. There is no evidence that the fever was imported into this house, but it was propagated from it to other parts of town, and 52 of the inhabitants were killed.
The poor suffered the most. Sorta like they do from the minimum wage law (tax) today.