The cold nights this week have many Iowans reaching for the thermostat. But even as we close doors and windows, it’s time to pay more attention to the air quality indoors. Tom Greiner is a retired extension ag engineer at Iowa State University who says it could be a matter of life and death.He says it’s important to have a qualified heating contractor come check the furnace before you turn it on for the season. Then, Greiner says it’s time to check your “life-safety” devices in the home. Hardware stores and many other stores have smoke alarms and he says you need a carbon-monoxide detector, too…as well as fresh batteries for all of them before you turn on the heat. If you’re using a heating alternative, it’s equally important to do a safety check. He says woodburning fireplaces produce high levels of carbon-monoxide so it’s even more important that you have both kinds of safety detectors. Greiner says if you plan to use the fireplace it’s time to call for a local chimney sweep to come clean the vents and inspect it for blockage or.