It is hereby declared that in certain areas of cities, towns and villages of the state there exist insanitary and substandard housing conditions owing to overcrowding and concentration of the population, improper planning, excessive land coverage, lack of proper light, air and space, insanitary design and arrangement, or lack of proper sanitary facilities; that these conditions are chiefly in areas where low rent dwellings prevail and that such conditions and dwellings are a menace to the health