CHICAGO (CBS) — People in or around southwest suburban Channahon might notice a whiff of some unpleasant odors in the air.

Channahon’s Odor Alert Network Coordinator Dan McDonald said, after a couple months with no odor complaint calls, he got two this week – one from neighboring Minooka, the other from Channahon. McDonald said he figures many other people smell those odors, as well, but don’t call.

“They claim that there was a odor in the air, much like rotten fish or rotten eggs”, he said.

McDonald said three plants in Channahon are causing the odors as they undergo some maintenance programs.

One of them, AkzoNobel Global, has been dredging waste treatment pits.

“They produce various cosmetic-type things, as well as other products, but I know they use a lot of animal by-products in their process, and that can stir up a little bit of a stink.”

The other nuisance odors – which McDonald said are not dangerous – were coming from the ExxonMobil plant, which is giving off a rotten egg smell; and Aux Sable Liquid Products, which is doing some maintenance that’s leaving a smell like mercaptan, the scent added to natural gas so you can detect a leak.

McDonald said residents can expect those odors to continue for a few weeks.

The Odor Alert Network has been around in Channahon for about five years. When residents call to complain, McDonald checks out the complaint, and if he can figure out where the smell is coming from, he reports back to the resident who complained.

Before this week, the last complaint call had come in in late March or early April.