For example, measurements show that past pollution controls have significantly decreased concentrations of lead, sulfur dioxide, and carbon monoxide, while there 
(measurements; show; that past pollution controls have significantly decreased concentrations of lead, sulfur dioxide, and carbon monoxide) Context(measurements show,List([13, 30))):(past pollution controls; have significantly decreased; concentrations of lead, sulfur dioxide, and carbon monoxide)
measurements show,List([13, 30))
measurements past pollution controls
show have significantly decreased
that past pollution controls have significantly decreased concentrations of lead, sulfur dioxide, and carbon monoxide
concentrations of lead, sulfur dioxide, and carbon monoxide