What potential causes of disease do you think either or both persons might have? Nathan Zimmer lives in an area of northeastern Pennsylvania where hydraulic fracturing for natural gas has elevated methane gas levels in his drinking water.

Sandi Smith lives in rural western Nebraska working outdoors much of the time managing her wheat farm.

Nathan Zimmer lives in Northeastern Pennsylvania which is an area with elevated methane gas levels in the drinking water. It is not toxic but highly explosive, however, a high concentration of methane gas level can lead to Asphyxiation. It is a condition that can cause death, in this person can not get enough amount of oxygen to lungs.

Sandi Smith lives in rural western Nebraska spends a long time on a wheat farm who can get allergic reactions due to dust from moldy hay, straw and grain. Pesticides and herbicides can result in chemical burns, respiratory illness, or poisoning.

the answer is ,10*4=40