Top 5 Air Purifiers For Large Spaces: Review & Guide

Does the air in your big living room or open-plan office feel stuffy or dusty? You might be sharing your space with invisible irritants like pollen, pet dander, or cooking odors. Breathing clean air is important for everyone, but keeping a large room fresh can feel like a huge challenge.

Finding the perfect air purifier for a big space is tricky. Many models just aren’t powerful enough to clean all that air effectively. You worry about wasting money on something that doesn’t work well, or buying a loud machine that constantly buzzes. It’s frustrating when you want clean air but don’t know where to start looking.

This guide cuts through the confusion. We will show you exactly what features matter most for large rooms, like CADR ratings and coverage area. By the end, you will know how to pick a powerful, quiet purifier that truly cleans your air. Get ready to transform your large space into a haven of fresh, healthy air!

Top Air Purifier For Large Rooms Recommendations

No. 1
LEVOIT Air Purifier for Home Allergens Pet Hair in Bedroom, Covers Up to 1073 ft² by 56W High Torque Motor, AHAM VERIFIDE, 3-in-1 Filter with HEPA Sleep Mode, Remove Dust Smoke Odor, Core300-P, White
  • WHY CHOOSE AHAM VERIFIDE AIR PURIFIERS: AHAM (Association of Home Appliance Manufacturers) is an ANSI-accredited organization that sets strict standards for appliance performance. Air purifiers with the AHAM VERIFIDE seal have been independently tested for air cleaning performance and energy efficiency. When you choose an AHAM certified air purifier, you're choosing a product trusted for reliable and effective indoor air quality improvement
  • HIGH-PERFORMANCE AIR PURIFICATION: A powerful 56W high-torque motor and 143 CFM CADR delivers fast, effective cleaning. The Levoit Original Filter is HEPA-grade while operating in Sleep Mode (Based on IEST RP C001.7). Ideal for home, bedroom, or office
  • AHAM VERIFIDE, PROVEN PERFORMANCE: AHAM VERIFIDE with a CADR (Clean Air Delivery Rate) rating of 143 CFM for smoke, 153 CFM for dust, and 167 CFM for pollen—refreshing air in a 222 ft² room 4.8 times per hour and a 1,073 ft² room once per hour
  • GENUINE REPLACEMENT FILTERS: For the best performance and longest lifespan, use official Levoit filters designed specifically for Levoit air purifiers. Levoit replacement filters ensure the best fit and high-efficiency filtration, while off-brand filters may be unreliable and may damage your Levoit air purifier
  • MULTIPLE FILTER CHOICES: Choose from a variety of replacement filters to best meet your needs. The Toxin Absorber Filter specializes in smog, toxins, and VOCs, while the Smoke Remover filter addresses smoke from wildfires, smoke, and other particulates. The Pet Allergy Filter captures pet dander and adsorbs unpleasant odors
No. 2
LEVOIT Air Purifiers for Home Large Room Up to 1875 Ft² with Washable Pre-Filter, AHAM VERIFIDE, Air Quality Monitor, HEPA Sleep Mode for Allergies, Pet Hair in Bedroom, Vital 200S-P, White
  • 𝐖𝐇𝐘 𝐂𝐇𝐎𝐎𝐒𝐄 𝐀𝐇𝐀𝐌 𝐕𝐄𝐑𝐈𝐅𝐈𝐃𝐄 𝐏𝐑𝐎𝐃𝐔𝐂𝐓𝐒: AHAM (Association of Home Appliance Manufacturers) is an ANSI-accredited organization that sets strict standards for appliance performance. Air purifiers with the AHAM VERIFIDE seal have been independently tested for air cleaning performance, safety, and energy efficiency. When you choose an AHAM certified air purifier, you're choosing a product trusted for reliable and effective indoor air quality improvement.
  • 𝐀𝐇𝐀𝐌 𝐕𝐄𝐑𝐈𝐅𝐈𝐃𝐄 & 𝐓𝐑𝐔𝐒𝐓𝐄𝐃 𝐁𝐘 𝐄𝐗𝐏𝐄𝐑𝐓𝐒: Certified by the Association of Home Appliance Manufacturers (AHAM), the Vital 200S-P has been independently tested to meet strict air purification and safety standards. CADR ratings include: Smoke: 250 CFM Dust: 254 CFM Pollen: 289 CFM
  • 𝐀𝐈𝐑 𝐏𝐔𝐑𝐈𝐅𝐈𝐄𝐑 𝐃𝐄𝐒𝐈𝐆𝐍𝐄𝐃 𝐅𝐎𝐑 𝐀𝐋𝐋𝐄𝐑𝐆𝐘 𝐆𝐑𝐎𝐔𝐏𝐒:The Vital 200S-P is designed specifically for allergy groups, effectively preventing allergens such as pollen, pet hair, dander, and dust from the air. Its efficient filtration system captures tiny particles, significantly improving indoor air quality and helping you and your family enjoy fresher air.
  • 𝐏𝐎𝐖𝐄𝐑𝐅𝐔𝐋 𝐖𝐇𝐎𝐋𝐄-𝐑𝐎𝐎𝐌 𝐀𝐈𝐑 𝐂𝐋𝐄𝐀𝐍𝐈𝐍𝐆: The LEVOIT Vital 200S-P Air Purifier delivers advanced air purification for large rooms up to 1875 sq ft. Ideal for living rooms, bedrooms, basements, and open-concept homes, it’s built to handle high traffic spaces and pet households.
  • 𝐇𝐈𝐆𝐇𝐄𝐑 𝐀𝐈𝐑 𝐈𝐍𝐓𝐀𝐊𝐄: Purify your air quickly. With a traditional air inlet and the additional U-shaped air inlet, airborne pet hairs and odors can easily be trapped without causing clogs
No. 3
KNKA Air Purifier for Home Bedroom Large Room Up to 1,695 Ft² in 1 Hr, HEPA Air Cleaner with Washable Pre-Filter, AQI Display, ECO Mode, Sleep Mode, Pet Mode for Pets, Dust, Pollen, APH4000
  • 𝐇𝐢𝐠𝐡 𝐂𝐀𝐃𝐑 𝐕𝐚𝐥𝐮𝐞: This air purifier provides reliable performance with a Smoke/Dust/PM2.5 CADR of 226 CFM (384 m³/h) and a Pollen CADR of 244 CFM (415 m³/h), ensuring effective and high-speed air purification for your home.
  • 𝐄𝐟𝐟𝐢𝐜𝐢𝐞𝐧𝐭 𝐀𝐢𝐫𝐟𝐥𝐨𝐰 𝐃𝐞𝐬𝐢𝐠𝐧: Engineered with dual front-and-back air intakes and dual side outlets, this purifier maximizes circulation for faster air exchange. It refreshes the air 4.8 times per hour in rooms up to 350 ft², reaching up to 80% purification efficiency, while still delivering 1 full air refresh per hour in larger spaces up to 1695 ft² with about 45% efficiency, helping maintain cleaner, fresher air throughout your home.
  • 𝐃𝐮𝐚𝐥 𝐅𝐢𝐥𝐭𝐞𝐫𝐬 & 𝟑-𝐒𝐭𝐚𝐠𝐞 𝐃𝐞𝐬𝐢𝐠𝐧: Equipped with dual front-and-back cartridges, each featuring a three-stage filtration system: a washable pre-filter for larger particles, a True HEPA filter, and an activated carbon filter. 3-in-1 filter system traps everything from pet hair to microscopic particles, ensuring thorough purification. (Please remove the filter’s plastic packaging before installation.)
  • 𝐏𝐄𝐓 & 𝐄𝐂𝐎 𝐌𝐨𝐝𝐞𝐬: PET Mode increases airflow to tackle pet hair, dander, and odors, refreshing the air in just 30 minutes. ECO Mode saves energy and extends filter lifespan by entering standby when air quality is excellent, then restarting automatically when purification is required.
  • 𝐌𝐮𝐥𝐭𝐢𝐩𝐥𝐞 𝐌𝐨𝐝𝐞𝐬 & 𝐅𝐚𝐧 𝐒𝐩𝐞𝐞𝐝𝐬: Includes Sleep Mode with noise levels as low as 22-24 dB for ultra-quiet nights, Auto Mode for effortless adjustments, and four fan speeds for personalized comfort. Select the setting that suits your needs any time of day.
No. 4
Air Purifiers for Home Large Room up to 2200sq.ft, MOOKA Air purifier for Home Pets with Washable Filter, PM 2.5 Display Air Quality Sensor Air Cleaner for Bedroom, Dorm room, Pets, Office PR1 (White)
  • MORE AIR INTAKE & HIGH-EFFICIENCY: This is the 2024 latest MOOKA PR1 HEPA air purifiers for home. To quickly purify the air without causing clogging, PR1 air purifier not only has normal surface air intake but only with a wider sided air inlet design, up to 2200 Ft². This effectively captures most air pollutants, which include pet hair, smoke, PM 2.5, and bad smell, and has powerful filtration performance against ultra-fine particles.
  • AIR PURIFIER DESIGNED FOR PET LOVERS: This home pet air purifier is innovatively designed with the "Pet Mode". In this mode the increased purification effect helps capture pet hair and pee smell in the air faster, significantly improving indoor air quality and helping you and your Families enjoy cleaner air. You can also water clean the washable pre-filter to extend the life of the 4-stage filtration system and dry the shade before using the air purifiers for home pets again.
  • DUST DETECTION & AIR QUALITY DISPLAY: This PR1 air purifiers for home large room is equipped with a PM2.5 sensor and will display real-time air quality levels on the air purifier screen. In Auto mode, the fan speed will automatically adjust to protect your air quality while you rest, you can clean it regularly to maintain the correction. Note: After powering on, the air purifier for the dorm is in a preheating state and the indicator light will continue to flash for one minute.
  • QUIET OPERATION & MULTI-FUNCTION: The air purifier for bedroom has 6 adjustable fan speed modes (Sleep/I/II/III/Auto/Pet), and the sleep mode is very quiet with noise as low as 26dB, so enjoy fresh air while sleeping sweetly. Additionally, the PR1 HEPA air purifier has a considerate Timer and Child Lock design. The aroma function can bring a pleasant aroma to the room or cover up an unpleasant smell. Tip: when the first time using an aroma, moisten the aroma pad with more essential oil.
  • FILTER REPLACEMENT REMINDER: Air purifiers are ideal for large indoor spaces, especially large bedroom, dorm, living room, office, nursery, apartment, basement and kitchen. This air purifier with washable filter has a filter replacement reminder function, the filter indicator light will light up to remind you to replace the filter. Press "Filter Reset" button for 3 seconds to reset it. We recommend buying official MOOKA filters to replace the filter every 3-6 months for optimal purification.(Search for B0DD3ZZ7ZV)
No. 5
WINIX 5510 Air Purifier (New Generation of 5500-2 with App Support) for Home Large Room Up to 1881 Ft² in 1 Hr, True HEPA, High Deodorization Carbon Filter and Auto Mode, Captures Pet Allergies, Smoke
  • 𝐀𝐇𝐀𝐌 𝐕𝐞𝐫𝐢𝐟𝐢𝐝𝐞 𝐚𝐭 𝟑92 𝐬𝐪 𝐟𝐭.: Also cleans rooms up to 1,882 sq ft in 1 hour (941 sq ft in 30 minutes, 627 sq ft in 20 minutes, 470 sq ft in 15 minutes)
  • 𝐖𝐢𝐧𝐢𝐱 𝐓𝐫𝐮𝐞 𝐇𝐄𝐏𝐀: Captures 99.99%* of airborne allergens including pollen, dust, smoke, and pet dander, as small as 0.01 microns
  • 𝐀𝐝𝐯𝐚𝐧𝐜𝐞𝐝 𝐎𝐝𝐨𝐫 𝐂𝐨𝐧𝐭𝐫𝐨𝐥 𝐂𝐚𝐫𝐛𝐨𝐧 𝐅𝐢𝐥𝐭𝐞𝐫: Reduces VOCs and household odors from cooking, pets, and smoke. It is designed to catch airborne particles found indoors, which also helps prolong the True HEPA Filter life
  • 𝐖𝐚𝐬𝐡𝐚𝐛𝐥𝐞 𝐅𝐢𝐧𝐞 𝐌𝐞𝐬𝐡 𝐏𝐫𝐞-𝐅𝐢𝐥𝐭𝐞𝐫: The first line of defense against the largest airborne particles found indoors
  • 𝐀𝐢𝐫 𝐐𝐮𝐚𝐥𝐢𝐭𝐲 𝐈𝐧𝐝𝐢𝐜𝐚𝐭𝐨𝐫: Visual indicator displays real-time air quality in the room with LED lights
No. 6
Air Purifiers for Home Large Rooms up to 3500 Ft², H13 True HEPA 0.1 Micron 99.97% Filtration with Carbon Filter, 235 CFM CADR, Removes Allergens, Pet Odor, Smoke, VOCs, 30dB Sleep Mode, PM2.5 Display
  • H13 True HEPA + Carbon Filter – Removes Allergens, Odors & Smoke: Equipped with H13 True HEPA (0.1μm, 99.97%) and an activated carbon filter, this purifier removes dust, pollen, pet dander, pet hair, cigarette smoke, wildfire smoke, VOCs, odors, and everyday particulates—ideal for allergy sufferers, pet owners, and households with smokers
  • 235 CFM CADR + Dual-Sided Airflow – Fast Purification for Large Rooms: The powerful 235 CFM CADR and dual-inlet airflow design deliver 2× faster circulation, cleaning 500 sq.ft in 15 minutes and covering up to 3500 ft². Perfect for large living rooms, open-concept homes, basements, pet activity areas, and offices
  • Quiet 30dB Sleep Mode – Ideal for Bedrooms & Light Sleepers: Sleep Mode lowers noise to just 30dB, and the dimmer function lets you adjust the panel brightness for comfortable nighttime use. It delivers cleaner air while you rest—perfect for children’s rooms, allergy relief during sleep, and pet owners who need overnight odor control
  • Smart PM2.5 Air Quality Display + Auto Mode – Real-Time Protection: The built-in Air Quality Monitor and PM2.5 digital display provide instant feedback. Auto Mode adjusts fan speed based on air quality—ideal for homes with pets, cooking odors, smokers, or daily allergens
  • Family-Safe Design – Floor Standing with Timer, Child Lock & Dimmer: Built for daily home use with Child Lock, Timer, and control panel dimmer—safe for kids, pets, and shared living spaces. The floor-standing design fits naturally in homes, living rooms, bedrooms, offices, and new home setups
No. 7
LEVOIT Air Purifier for Home Large Room Up to 1073Ft² with Air Quality Monitor, AHAM VERIFIDE, Smart WiFi, Washable Pre-Filter, HEPA Sleep Mode for Pets, Allergies, Dust, Pollen, Vital 100S-P, White
  • 𝐖𝐇𝐘 𝐂𝐇𝐎𝐎𝐒𝐄 𝐀𝐇𝐀𝐌 𝐕𝐄𝐑𝐈𝐅𝐈𝐃𝐄 𝐀𝐈𝐑 𝐏𝐔𝐑𝐈𝐅𝐈𝐄𝐑𝐒: AHAM (Association of Home Appliance Manufacturers) is an ANSI-accredited organization that sets strict standards for appliance performance. Air purifiers with the AHAM VERIFIDE seal have been independently tested for air cleaning performance and energy efficiency. When you choose an AHAM certified air purifier, you're choosing a product trusted for reliable and effective indoor air quality improvement
  • 𝐀𝐇𝐀𝐌 𝐕𝐄𝐑𝐈𝐅𝐈𝐃𝐄 𝐄𝐅𝐅𝐄𝐂𝐓𝐈𝐕𝐄 𝐏𝐔𝐑𝐈𝐅𝐈𝐂𝐀𝐓𝐈𝐎𝐍: The Vital 100S-P Air Purifier has undergone rigorous testing and can purify the air 4.8x per hour in rooms as large as 222 ft². In areas up to 1,073 ft², it cleans the air once per hour, making it an ideal choice for open-concept living spaces
  • 𝐏𝐄𝐓 𝐎𝐖𝐍𝐄𝐑𝐒 𝐅𝐑𝐈𝐄𝐍𝐃𝐋𝐘: Pet Mode cleans the air, while the wide U-shaped air inlet effectively traps airborne pet fur and large particles
  • 𝐇𝐈𝐆𝐇 𝐏𝐄𝐑𝐅𝐎𝐑𝐌𝐀𝐍𝐂𝐄: Vital 100S-P offers powerful filtration, with 99.97% filtration efficiency in capturing fine particles sized 0.1-0.3μm, such as pollen, dust, and pet dander
  • 𝐇𝐄𝐏𝐀 𝐒𝐋𝐄𝐄𝐏 𝐌𝐎𝐃𝐄: Vital 100S-P uses light detection to automatically dim the display in dark environments and uses Sleep Mode to quiet fan speeds to as low as 23dB so it won't disturb your peaceful rest. Levoit Original Filter achieves HEPA-grade filtration during Sleep Mode, independently tested
No. 8
Air Purifiers for Home Large Room, Cover Up to 2600 Ft² with Washable Filters, Powerful Turbo Mode, PM2.5 Air Quality Display, 22dB Sleep Mode, Air Cleaner for Pets Hair, Smoke, HAP607, White
  • 𝐓𝐑𝐈𝐏𝐋𝐄 𝐈𝐍𝐓𝐀𝐊𝐄, 𝐖𝐇𝐎𝐋𝐄-𝐑𝐎𝐎𝐌 𝐏𝐔𝐑𝐈𝐅𝐈𝐂𝐀𝐓𝐈𝐎𝐍: Featuring a front air inlet combined with wider dual-side air inlets, this air purifier maximizes airflow and accelerates circulation for faster purification. The high-efficiency HEPA filter captures 99.97% of airborne particles, including pet hair, dander, dust, smoke, and odors. Perfect for pet owners and large rooms, it refreshes up to 2600 ft² per hour, ensuring a cleaner, healthier environment for the whole family.
  • 𝐑𝐄𝐀𝐋-𝐓𝐈𝐌𝐄 𝐂𝐇𝐄𝐂𝐊, 𝐄𝐅𝐅𝐎𝐑𝐓𝐋𝐄𝐒𝐒 𝐅𝐑𝐄𝐒𝐇𝐍𝐄𝐒𝐒: Equipped with an advanced PM2.5 sensor, this air purifier shows real-time air quality levels on its display, so you always know the air you breathe. In Auto Mode, it automatically adjusts fan speed based on detected air quality, delivering cleaner air when pollution rises, and saving energy when the air is fresh, all without any guesswork.
  • 𝐖𝐀𝐒𝐇𝐀𝐁𝐋𝐄 𝐅𝐈𝐋𝐓𝐄𝐑, 𝐋𝐀𝐒𝐓𝐈𝐍𝐆 𝐏𝐄𝐑𝐅𝐎𝐑𝐌𝐀𝐍𝐂𝐄: Unlike other washable filters made of sponge without a frame, our pre-filter uses a sturdy grid-structured hard plastic frame that resists deformation and supports long-term use. Simply rinse or vacuum to clean, keeping filtration performance strong while extending the life of the HEPA filter, saving you money and reducing waste.
  • 𝐅𝐋𝐄𝐗𝐈𝐁𝐋𝐄 𝐒𝐏𝐄𝐄𝐃𝐒, 𝐓𝐈𝐌𝐄𝐃 𝐅𝐑𝐄𝐒𝐇 𝐀𝐈𝐑: This air purifier offers 4 adjustable fan speeds, low, medium, high, and turbo, so you can control purification speed as needed. The 2/4/6/8-hour timer lets you run it while sleeping or away from home, saving energy without sacrificing clean air.
  • 𝐐𝐔𝐈𝐄𝐓 𝐍𝐈𝐆𝐇𝐓, 𝐏𝐔𝐑𝐄 𝐂𝐎𝐌𝐅𝐎𝐑𝐓: In Sleep Mode, the purifier operates ultra-quietly at 22 dB with no bright lights, perfect for bedrooms. Wake up refreshed knowing your room was filled with clean air all night.

The Ultimate Buying Guide: Choosing the Best Air Purifier for Your Large Space

Do you have a big living room, open-plan kitchen, or spacious bedroom? These areas need powerful air purifiers. A small unit just won’t cut it. This guide helps you pick the right machine to keep your large room breathing easy.

1. Key Features to Look For

When shopping, focus on these important features. They determine how well the purifier cleans your air.

Coverage Area (CADR Rating)

  • CADR Matters Most: CADR stands for Clean Air Delivery Rate. This number tells you how fast the purifier cleans the air. For large rooms (over 400 sq. ft.), look for high CADR numbers, especially for smoke and dust.
  • Match the Room Size: Always check the manufacturer’s recommended room size. It is better to buy a slightly oversized unit than an undersized one.

Filtration System

  • True HEPA Filter: This is the heart of any good purifier. A True HEPA filter must capture 99.97% of particles as small as 0.3 microns. This handles dust, pollen, and pet dander easily.
  • Activated Carbon Filter: This layer absorbs odors, smoke, and volatile organic compounds (VOCs) from paints or cleaning supplies.

Noise Level and Settings

  • Decibel (dB) Rating: Large room purifiers can be loud on high settings. Check the lowest setting’s dB level. Below 30dB is very quiet, perfect for sleeping.

2. Important Materials in Your Purifier

The materials used affect performance and longevity.

Filter Media

  • Filter Quality: High-quality HEPA filters use densely packed, layered fibers. Cheap filters might look similar but let tiny particles slip through.
  • Filter Housing: Ensure the filter fits snugly into the unit. Poor seals mean dirty air bypasses the filter.

Outer Casing

  • Durable Plastic or Metal: Most units use sturdy ABS plastic. Premium models might use metal for better durability and a sleeker look.

3. Factors That Improve or Reduce Quality

These details separate the good purifiers from the great ones.

Factors That Improve Quality

  • Air Circulation Design: Units with 360-degree air intake pull air from all directions, which cleans large spaces faster.
  • Smart Sensors: Automatic modes use laser sensors to detect pollution levels. The machine adjusts its fan speed automatically, saving energy and keeping air consistently clean.

Factors That Reduce Quality

  • Ozone Emission: Avoid purifiers that intentionally generate ozone (sometimes marketed as “air fresheners”). Ozone is a lung irritant. Stick to HEPA and carbon filtration.
  • Proprietary Filters: Some brands force you to buy their expensive, specific replacement filters. Check the cost and availability of replacements beforehand.

4. User Experience and Use Cases

Think about where and how you will use the machine.

Ease of Use

  • Filter Replacement: Can you change the filters easily without tools? Simple designs make maintenance less of a chore.
  • Controls: Look for clear digital displays or simple touch controls. Wi-Fi connectivity allows you to control the unit from your phone.

Common Use Cases

  • Open Concept Living: If you combine your living room and dining room, you need a purifier rated for the total square footage.
  • Pet Owners: High pet dander requires a strong unit with excellent pre-filters to catch large hairs before they clog the HEPA filter.
  • Allergy Sufferers: Focus on the highest CADR rating and ensure the True HEPA filter is certified.

10 Frequently Asked Questions (FAQ) About Large Room Air Purifiers

Q: How often should I replace the filters in a large room purifier?

A: Most manufacturers recommend changing HEPA and carbon filters every 6 to 12 months. This depends on how polluted your air is. If you run it constantly or have pets, you might need to replace them sooner.

Q: Are large air purifiers expensive to run?

A: Modern units are quite energy efficient, especially when using the automatic or low setting. They usually use about as much electricity as a standard light bulb.

Q: What does “air changes per hour” (ACH) mean?

A: ACH is how many times the purifier cleans all the air in the room within one hour. For allergy sufferers, aim for 4 to 5 ACH. For general cleaning, 2 ACH is often enough.

Q: Can one large purifier cover two connected rooms?

A: Yes, if the combined area matches the purifier’s maximum coverage rating. Remember that open doorways help air flow, but walls block it. Always calculate the total square footage.

Q: Should I leave the purifier running all the time?

A: Yes, for the best results, leave it running. Air pollution happens constantly. Running it on a low or auto setting keeps the air clean without wasting energy.

Q: What is the difference between a HEPA filter and a washable filter?

A: A True HEPA filter traps microscopic particles and must be replaced. Washable filters catch large dust and might be reused, but they do not offer the same level of filtration for tiny allergens.

Q: Will a large purifier remove cooking smells?

A: It will help significantly, but only if it has a substantial activated carbon filter. Carbon absorbs odors. Run it on high while cooking for the best odor removal.

Q: What does “Energy Star Certified” mean?

A: This certification means the product meets strict energy efficiency guidelines set by the government. It confirms the unit saves energy while performing well.

Q: Are smart features like Wi-Fi worth the extra cost?

A: Smart features are very useful for large rooms. They allow you to check air quality readings remotely or set schedules, ensuring the machine runs when you are away or asleep.

Q: How do I know if my purifier is actually working?

A: Look for an air quality indicator light that changes from red (bad) to blue or green (good). Also, notice if you feel less dust or smell fewer odors in the room after running it for a few hours.