While there are plenty of commercial products on the market claiming to remove odors from the air, some can cause a reaction in people with allergies. Try an all-natural alternative to mask the odor until it dissipates. It may be more friendly to people with sensitive skin and noses.
The simplest method to reduce odor is to fill a small bowl with vinegar and set it on the kitchen counter or on top of the refrigerator. Or simmer whole cinnamon sticks, cloves and orange peel on the stove. Sprinkling dried cinnamon or cloves on a cookie sheet or shallow pan and setting it on the stove top or in the oven on very low heat also masks onion odors. Crack the door on the oven if you can't smell the spices.
For long-term deodorizing in the cool months, fill a fine mesh bag or a section of pantyhose with whole cinnamon, cloves or other aromatic spices. Seal the bag or tie off the ends of the pantyhose and place the homemade sachet inside a heating vent. When the heat comes on, the aroma fills the air.