The article discusses how income inequality may or may not affect health. The author looks at different ways to measure health inequality and how it relates to income inequality. They suggest that within-group income inequality doesn't impact average health, but the slope of the relationship between health and income depends on the ratio of between-group to within-group income inequality. The author also examines data from different countries and time periods, finding little evidence that income inequality is a direct health hazard at the national level. However, they do find a clear health gradient that increases with income inequality within specific cohorts.