Selected aspects of the population health status in ecological hazard areas in comparison with ecologically "clean" area. I. Methodology for analysing health status of the population living in ecological hazard areas based on the routine data collection system - Dutkiewicz, Tadeusz; Andryszek, Czesław; Kończalik, Jerzy; Rachański, Dariusz (Instytut Medycyny Pracy w Łodzi im. prof. J. Nofera)