(AP) — Nebraskans with private water wells can have their drinking water tested for nitrates during the Scotts Bluff County Fair this week.

Those wanting to take advantage of the free testing are asked to bring a cup-size sample of water in a clean bottle to the Scotts Bluff County Health Department/Nebraska Department of Health and Human Services booth. The test is free.

The fair begins Tuesday and runs through Saturday.

Nitrates are a concern for infants under six months of age and pregnant women, as well as anyone who has a weakened immune system. High levels of nitrates interfere with the blood’s ability to carry oxygen and can cause “blue baby” syndrome.

Livestock are also susceptible to nitrate poisoning.