Factors in Population Growth The key factors in population change are natural increase (the number of births minus the number of deaths), net migration, and the interplay between these elements. These factors are in turn driven by fertility rates, the age structure of the population, mortality rates, life expectancy, and rates of in- and out-migration.
Federal law requires that before signing a lease for housing built before 1978, renters must receive the following from your landlord: An EPA-approved information pamphlet on identifying and controlling lead-based paint hazards, Protect Your Family From Lead In Your Home (PDF).
Starting in 1973, the federal government started a gradual phase-down of lead content in gasoline, and by 1996, banned the sale completely. However, lead from car exhausts mixed with soil near roads and is still there today. Homes near busy streets may have higher levels of lead in the soil. Today, lead still comes from metal smelting, battery manufacturing, and other factories that use lead. This lead gets into the air and then mixes with the soil near homes, especially if the home is near one of these sources.