Problems caused by the leaching of pollutants from dumps and landfills are worst in countries with an annual per capita economic output of $4, 000 to $5, 000, and less severe for considerably poorer and considerably richer countries. This is so because pollution problems increase during the early stages of a country' s industrial development but then diminish as increasing industrial development generates adequate resources to tackle such problems. Ttherefore, problems caused by such leaching in Country X, where the annual per capita economic output is now $5, 000, should begin to diminish in the next few years.
Industrial development in Country X will increase in the next few years is an assumption on which the argument depends.