Whether return vents need filters depends entirely on where your main HVAC filter is located. You should only have one filter in your system—either at the main air handler/furnace or in the return vent, but never both. Using multiple filters will overly restrict airflow, straining your system and increasing energy bills.
You should only use an air filter in the HVAC unit OR the return vent, not both. Additional air filters will only decrease airflow within your home, creating airflow issues. There are plenty of advantages of return vent filters.
Yes, air purifiers help by capturing airborne viral particles (including the flu) and removing respiratory droplets from the air. While they do not prevent direct transmission or touching contaminated surfaces, they are highly recommended by health authorities to reduce the concentration of indoor germs.
Air purifiers do not dry out the air—they are designed to remove pollutants, not moisture. If you experience dryness, it's likely due to environmental factors like heating systems or low outdoor humidity.
For chemotherapy patients, the ideal air purifier must have a True HEPA filter (to capture microscopic pathogens and allergens) and an activated carbon filter (to neutralize VOCs and chemical odors that trigger nausea). Top clinical-grade choices include:
Cleaning for a chemotherapy patient requires balancing a germ-free environment with a chemical-free atmosphere. Because chemotherapy compromises the immune system, you must rigorously disinfect high-touch areas, but you must also use gentle, non-toxic products to protect the patient from harsh fumes and nausea.
The best medical-grade air purifiers, based on over 100 tests
Here are five clear signs your home air is too dry—and what helps.
The generation of secondary pollutants
Certain purification technologies carry the risk of incomplete reactions: the chemical breakdown of targeted pollutants can then generate secondary irritant pollutants, sometimes even more toxic than the eliminated component!
High or low humidity, particularly during winter months, can trigger your allergies and humidity is a bigger factor in whether or not your sinuses are dry. Adding an air purifier can help relieve your allergies by removing the particles in the air but they do not impact moisture in the air.
You likely need an air purifier if you or your family members experience chronic allergy symptoms (sneezing, itchy eyes), have respiratory conditions like asthma, share your home with shedding pets, notice persistent cooking or musty odors, or live in an area with high outdoor pollution or wildfire smoke.
Follow the 2/3 Rule
As a rule of thumb, the CADR of your air cleaner should be equal to at least two-thirds of the room's area. For example, a room with the dimensions of 10 feet by 12 feet has an area of 120 square feet. It would be best to have an air cleaner with a smoke CADR of at least 80.
HEPA air purifiers may boost brain power in adults over 40 – new research. Using an in-home HEPA purifier for one month spurs a small but significant improvement in brain function in adults age 40 and older. That's the result of a new study we co-authored in the journal Scientific Reports.
Installing a return air vent filter is a quick process. First, turn off your HVAC system to prevent dust from circulating. Open the vent latches, remove the old filter, and insert the new one, ensuring the arrows point inward toward the ductwork. Finally, close and latch the vent securely.
Conclusion. A dirty air filter does more than just reduce your HVAC system's efficiency—it can also compromise your family's health by allowing mold, dust, and other harmful particles to circulate through your home.
Clean the Return Vent Cover Regularly
Dust and debris build up on return air grilles and air conditioner vent covers, blocking airflow and reducing efficiency. Clean your vent cover with a vacuum, a soft brush attachment, or a damp cloth every month. If you have decorative air vent coverings, clean them well, too.
Is it safe to run an air purifier all day? Yes, most modern filtration-based air purifiers are designed for continuous operation.
No, standard air purifiers do not physically remove moisture from the air. They merely cycle air through filters (like HEPA and carbon) to trap pollutants. However, the continuous airflow from the device's fan can increase evaporation from your skin and nasal passages, making the air feel drier.
3) Never buy an air purifier that has less than a 2.5-inch deep bed of carbon. The third air purifier you should never buy is one that doesn't have enough carbon. As I mentioned earlier, activated carbon is the most important filter to get rid of chemicals and odors in the ambient air.
No, 40% humidity is not too low. In fact, it is considered the ideal sweet spot for indoor environments. Major health and environmental organizations generally recommend keeping indoor relative humidity between 30% and 50% (or up to 60%) to ensure maximum comfort and prevent issues like mold or dryness.
Dry air problems don't fix themselves. They get worse as winter progresses, especially during those extended Santa Ana periods when outdoor humidity drops to desert levels.
The most accurate way to test for dry air is to use a digital hygrometer. For a quick DIY check, use the ice cube method: fill a glass with ice and water, wait 5 minutes; if no condensation forms on the glass, your air is too dry.
The best air purifier depends on your room size and specific needs, but the Blueair Blue Pure 311i Max is widely recommended as the best overall choice. It delivers top-tier smoke and particle filtration, operates quietly, and is highly energy-efficient, making it perfect for medium to large living spaces.
Consumer Reports named Blueair the top-rated air purifier brand overall, highlighting its superior particle removal at both high and low fan speeds, quiet operation, and excellent predicted reliability. Standout models evaluated highly by industry experts include the Blue Pure 211i Max and the Levoit Core 200S.
The safest air purifiers use only mechanical True HEPA filtration and activated carbon. They are strictly ozone-free, meaning they do not use ionizers, UV-C lights, or photocatalytic oxidation (PCO) that can produce harmful byproducts like ozone.