How Long To Run An Air Purifier? Can You Leave It On All Day?

For those who just started using an air purifier, one might wonder how long I should run an air purifier or should I leave it on all day, all night. Wonder no more, as we will address how fast and effective an air purifier can be in cleaning the air. We also compiled other common questions related to the runtime, including why it is crucial to keep an air cleaner running. Give this post a quick run-through regardless of whether you are a beginner or a veteran in the air purifying world.


How Long Should You Run An Air Purifier?

At least 12 hours a day. If you cannot run an air purifier 24/ 7, you can optimize the performance by choosing the highest speed for at least 30 minutes to 2 hours before entering the room or until the air quality indicator turns green. Doing so allows air purifiers to remove 95% to 99.97% of dust and other airborne pollutants. To maintain the room air quality level, switch back to low speed and allow the air purifier to run continually in the background, as airborne pollutants will circulate nonstop throughout the day. 

Should I Leave My Air Purifier On 24/ 7

It is OK to keep an air purifier on all the time, even if you are not at home. It will maintain fresh, purified air every time you step foot in a house after a long day at work or an extended holiday. With constant clean air free from airborne irritants, you can breathe comfortably without suffering from allergies like cough, sinus, red eyes, headache, and itchiness. Every time an air purifier is turned off, it will stop filtering the air, and the cleaning cycle will have to restart again. Harmful particles like dust, pet dander, mold, pollen, bacteria, and viruses will gradually return within 2 to 4 hours, resulting in a drop in indoor air quality. The health effects of air pollution are pervasive, but the risk can be reduced when the air purifier is kept on. 

Should I Sleep With Air Purifier On All Night?

Is It Safe To Run An Air Purifier All The Time?

It is perfectly safe to leave a HEPA air purifier on day and night as it is designed to run 24×7 without overheating, breaking down, or releasing harmful byproducts. Most models are also CE/ UL listed with strict safety compliances and CARB certified to be ozone-free. The only time you should not be running an air purifier is when there is a safety hazard, such as a damaged power cord, an ozone generator that diffuses harmful ozone, or dirty filters that will hamper its filtration efficiency.

Should I Sleep With Air Purifier On All Night?

Yes, you should, as we spend about one-third of our life sleeping in the bedroom. Light sleeper or not, sleeping with an air purifier on every night improves the quality of sleep and your health. It prevents airborne allergens from building up overnight that can trigger allergic reactions e.g. night cough, choking, sinus. According to The Asthma and Allergy Foundation of America (AAFA), an air purifier promotes better breathing by reducing airborne irritants that could disturb your sleep. You will wake up in a happier mood, laser-focused, and feeling completely refreshed the next day. Note that not all air cleaners are suitable for nighttime use because of the loud fan noise. For a night of uninterrupted sleep, get a quiet bedroom air purifier and leave it close to you, preferably by the bedside/ nightstand. The closer it is to your breathing zone, the shorter the time clean air travels before reaching you.

How Long Should You Run An Air Purifier

How To Reduce An Air Purifier’s Cleaning Time?

We mentioned the right type and size of air purifier could significantly decrease the running time. Practice the steps below to maximize air purifier performance and efficiency in improving indoor air quality.

  • Clean Air Delivery Rate (CADR) – The higher the CADR, the quicker an air purifier can deliver clean air. An official AHAM measurement in assessing how well a residential air purifier works in removing different sizes of airborne particles. Three separate tests were measured in cubic feet per minute (cfm) with 80% filtration efficiency against dust, pollen, and smoke particles.
  • Air Changes Per Hour (ACH) – Check if the air purifier’s suggested room size is calculated at 2 ACH to avoid confusion. The extraction rate is a figure of how much air can be cleaned from a room in an hour. For example, an air cleaner running at four air changes per hour (15 minutes one charge) only takes half the time to clean the air compared with the same air cleaner running at two air changes per hour.
  • Room size – Pick the right size air purifier e.g. tabletop, tower, or a console, that fits your home. The air cleaner must also have enough airflow capacity to fulfill the exact room size specification. Otherwise, it will have to run endlessly to clean the room. For instance, a 300 square feet room requires a large air purifier with a suggested room size of at least 300 square feet.
  • Filtration types – The more filtration, the better. Most mechanical air purifiers come standard with a pre-filter, HEPA filter, and activated carbon filters. Some models come with an additional medium filter, antimicrobial, or addon filter that is customizable according to your needs. Note that the more filters there are, the slower the airflow will output; a longer cleaning time is needed.
  • Seasonal adaptation – Location and weather also play a significant factor in how quickly an air purifier will work. For example, more air pollutants like pollen will spread during the summer, increasing the time needed to clean the air.
  • Close windows and doors when an air purifier is running – It prevents outside contaminants from entering the room and clean air from escaping. Only leave windows and doors open when you need quick fresh air and when an air purifier is not present, such as after cooking, dusting, or cigarette break.
  • Silence is golden – Ensure the air purifier noise level is acceptable, preferably under 60 dB, so you can live comfortably with it throughout the day.
  • Perform regular maintenance, including filter change and monthly cleaning. Ensure the air purifier is in working condition by checking if the airflow is coming out of the ventilation. A working air purifier will continuously draw dirty air and release clean air.
  • Schedule filter change – It is vital to regularly check the filter condition. Gently clean the pre-filter every 2-3 weeks with a vacuum brush. Replace the HEPA/ carbon filters accordingly or when the filter change indicator is flashing to maintain filtration efficiency. A working air purifier will continuously draw dirty air and releases clean air.
  • Give it some space – Place an air purifier 2-4 feet away from the wall or furniture to prevent airflow circulation obstruction. We recommend placing an air purifier near a doorway or windows with the highest moving air point. In any case, never leave it underneath a window, wet area, or electronic device to prevent necessary damage.
  • Get more than one air purifier – Having multiple air purifiers in a room will not make you sick and dry out the air. It will increase the purifying coverage and the removal of airborne pollutants at a given time. If you are content with only 1, move it from room to room purifying so the air purifier will be first-hand in removing the nearby pollutants in the air.
  • House cleaning – Keep your room clean by vacuuming regularly to reduce dust and the air purifier workload.
Can You Leave Air Purifier On All The Time

Is It Costly To Run An Air Purifier All Day?

It is not costly to run an air purifier 24 hours a day compared with other home appliances. It will only cost you an estimate of $0.08 to $0.30 daily, depending on the airflow speed, power wattage, and states you're in. Some model even has a power consumption rate equivalent to a light bulb. Regardless of how long the air purifier runs, you will not see a huge spike in your electric bills.

We do not recommend running an air cleaner intermittently in order to save costs. It is far from economical, and you will be at risk of inhaling harmful contaminants when the air purifier is off. The air cleaner will struggle to restore the clean air state and may end up using more energy. Instead, pick an Energy Star Rated air cleaner or model with an energy-saving Auto mode that only uses higher fan speed when a high concentration level of pollutants is detected.

To calculate the running cost of an air purifier, multiply the energy consumption by the state rate of electricity and hours of operation. For the monthly electricity bill, multiply the cost by 30 days.

Is It Safe To Run An Air Purifier All The Time?

Final Thoughts

We hope this post addressed the misconception that running an air cleaner for a few hours is enough to provide you with clean air for the rest of the day. Airborne pollutants never stop; therefore, an air purifier should not have to work around the clock. Don't waste your hard-earned money by letting the air cleaner sit in the corner doing nothing. Let it work its magic to provide fresh air as intended.

Max Fernandez

A loving father and a dedicated reviewer for airfuji.com with more than 1000 air purifiers under his belt. Max Fernandez is also one of the million patients currently suffering from asthma. Feel free to nudge him if you have any questions.
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