You can't tell by smell. The EPA lists gas stoves among the sources of carbon monoxide inside a home, and the CPSC names malfunctioning ranges as one of them. Carbon monoxide has no color, smell or taste, so an alarm is the only reliable way to know it's in your kitchen.

There are signs you can check tonight, though, and habits that cut the risk. Start by separating the two dangers a gas stove can bring.

A gas smell and carbon monoxide are two different dangers

That rotten-egg smell near the stove is natural gas. Natural gas has no odor on its own, so utilities add a chemical called mercaptan to make leaks easy to notice, according to Connecticut's utility regulator. Carbon monoxide gets no warning smell at all.

So a gas smell means a possible gas leak (here's what to do about a gas leak). And a kitchen that smells fine can still have carbon monoxide in the air.

Signs your stove may be making carbon monoxide

The Minnesota Department of Health lists these warning signs around fuel-burning appliances:

• Orange or yellow flames. A gas burner's flame should be blue.
• Soot. Streaks of soot around the stove or other gas appliances.
• Moisture. Extra condensation on windows, walls and cold surfaces.
• Symptoms that follow the stove. Headaches or breathlessness that start, or get worse, when the stove or other gas equipment is running.

More signs are in our guide to how to detect carbon monoxide, and what causes carbon monoxide in a house covers the furnace, water heater and garage.

Habits that raise carbon monoxide in the kitchen

• Heating the house with the oven or burners. The CPSC, Mayo Clinic and the Minnesota Department of Health all say never to do this.
• Cooking without the vent fan. The EPA recommends installing an exhaust fan over a gas stove that vents to the outdoors, and using it.
• Letting maintenance slide. The EPA says to keep gas appliances properly adjusted. If you see yellow flames or soot, have a professional check the stove.
• Skipping the yearly heating check. The CPSC says to have your heating system professionally inspected and serviced every year.

A quick check you can do tonight

1. Light each burner and look at the flame. You want blue. Orange or yellow means call a professional.
2. Look behind and around the stove for soot streaks on the wall, the backsplash or the hood.
3. Check the kitchen windows and walls for extra condensation.
4. Count your CO alarms. The CPSC says you need one on every level of your home and outside sleeping areas, battery-operated or with a battery backup.

Symptoms to watch for

The CDC lists headache, dizziness, weakness, upset stomach, vomiting, chest pain and confusion. They're often described as flu-like, and the CPSC notes there's no fever. If you feel sick while the stove is running and better once you step outside, take it seriously. See the full list of carbon monoxide poisoning symptoms.

What to do if you suspect carbon monoxide or smell gas

If a CO alarm sounds or anyone has symptoms: get everyone outside right away, then call 911. Stay out until responders say it's safe.

If you smell gas: leave the house if the smell is strong or you aren't sure. On your way out, don't touch light switches, use the phone or light anything. Call your gas company or 911 from outside or a neighbor's house.

For questions about a possible carbon monoxide exposure, Poison Help is free at 1-800-222-1222, 24 hours a day.

Put an alarm near the stove

A standard CO alarm doesn't pick up gas leaks, and a gas stove can bring both dangers into your kitchen. The Hero Dual Threat Detector checks the air for both.

Inside are two sensors. One measures carbon monoxide, from 0 to 1,000 parts per million. The other picks up natural gas, methane and propane. A live readout shows both numbers, and if either one climbs you hear an alarm, then a faster, urgent one at higher levels. There's nothing to wire and no app to set up.

Plug it into an outlet 3 to 6 feet to the side of the stove. Right above the burners, cooking heat and fumes can throw off the sensor. It runs on wall power with no battery, so keep your battery CO alarms on every level too.

Cook tonight knowing something is watching the air. Get the Hero Dual Threat Detector.