Meanwhile, other areas can harbor germs from our gastrointestinal tract and respiratory system anytime we use the bathroom, cough, sneeze, and wash our mouth in the sink, Banjoko adds. These germs have the potential to contribute to sickness, too. The moral of the story: Good health begins at home. So start the season on a healthy note by making sure to include these often-neglected areas in your spring-cleaning routine.

1. Windowsills

“Windowsills are an easy place for mold to grow, and it’s not always apparent to homeowners,” says Tim Dunphy, product manager at Leaf Home Water Solutions, a water purification company in Jacksonville, Florida. Mold spores appear as small, discolored areas on your windowsills and, if left untreated, can damage your window and home air quality, he says. According to the Centers for Disease Control and Prevention (CDC), exposure to mold can cause people with asthma and mold allergies to experience symptoms such as stuffy nose, wheezing, and red or itchy eyes or skin. The National Academies of Sciences, Engineering, and Medicine has also found a link between mold exposure and upper respiratory tract symptoms, cough, and wheeze in healthy people. The American Academy of Allergy, Asthma, and Immunology recommends cleaning mold and condensation from window frames and sills with a solution of chlorine bleach: Mix ¾ cup of chlorine bleach with 1 gallon of water. Be sure to wear a protective mask and rubber gloves.

2. HVAC Filters

If your home has a central heating, ventilation, and air-conditioning system, change the filter regularly, says Jessica Hui, MD, allergy and immunology physician at National Jewish Health in Denver. Filters catch particles that affect the air quality inside your home, including pollen, animal allergens, and mold spores, according to the American College of Allergy, Asthma, and Immunology (ACAAI). If you let the filters fill up and sit too long, it can worsen allergy and asthma symptoms. The ACAAI recommends replacing your air filter about every three months. Start the habit during spring-cleaning.

3. Base of Toilets

Even if you clean your toilets regularly, chances are you skip the base where the toilet is held to the ground. “I tend to see pee just sitting on the base of the toilet, especially when I visit homes with little kids,” Banjoko says. Urine left on the base of the toilet (or anywhere, really) can harbor germs, while the moisture can contribute to mold that can increase the risk for or worsen respiratory ailments like allergies and asthma Banjoko recommends using bleach or a product that’s been labeled with words like “antibacterial” or “antimicrobial” to clean these germy areas. According to the American Cleaning Institute, common ingredients to look for on the label include pine oil, quaternary ammonium compounds, sodium hypochlorite, phenols, and ethanol.

4. Water Filters

“Homeowners don’t tend to their water filtration systems because they aren’t top of mind, and some households can go months or years without properly cleaning or replacing their filters,” Dunphy says. An old filter can develop mold, which immediately affects the quality of your water and, by extension, your family’s health. According to the U.S. Food Safety and Inspection Service, ingesting some molds can cause allergic reactions and respiratory problems, whereas others can make you sick. How often you need to clean or replace a filter depends on the appliance, so check the manufacturer’s instructions for guidance. As a general guideline, replace your refrigerator filter every three to nine months, according to Dunphy. If you have a whole home water treatment system to purify your tap water, replace the filter every three to seven years.

5. Closets and Mudrooms

Dunphy says that closets and mudrooms get a ton of traffic, such as from you and your family kicking off winter boots, stacking your coats and jackets, and dropping off sweaty gym bags. Winter weather, in particular, tends to introduce moisture to these areas, such as from melted snow, leading to mold when left to sit. Give your closets and mudrooms a deep clean with your go-to cleaning products at the beginning of each season. Dunphy recommends removing all items before cleaning so you can get into every nook and cranny.

6. Pets

Don’t forget your four-legged friends! Fido can bring dirt, dander, and outdoor allergens like pollen into the house, worsening allergies and introducing new germs. According to the CDC, dogs can carry germs that can cause a variety of illnesses in people, from minor infections like ringworm to serious illnesses like methicillin-resistant Staphylococcus aureus. Cats can cause many of the same infections and illnesses, along with cat-specific ones like cat scratch disease (a mild infection), per the CDC. “It’s important to groom them frequently to minimize dander exposure and clean them of allergens they’ve picked up outdoors,” Dr. Hui says. Bring pets to a professional groomer or give them a DIY at-home bath. Also, get in the habit of providing your pets with routine veterinary care and washing your hands thoroughly after interacting with them, per the CDC.

7. Gutters

“Since gutters are out of sight, they’re often forgotten when spring-cleaning rolls around. However, it’s recommended that you check and clean your gutters every six months to prevent overflow,” Dunphy says. The benefit of cleaning them in the spring is that you can get rid of any debris or water that may have built up over the winter from ice dams. According to the University of Minnesota, an ice dam is a ridge of ice that forms at the edge of your roof and prevents snowmelt from draining. The water that backs up behind the dam can leak into your home, causing mold and mildew to grow.