FAQ
Frequently Asked Questions
Get expert answers to the most common air purifier questions. From choosing the right size to maintenance tips and performance expectations.
Choosing an Air Purifier
What size air purifier do I need for my room?
The air purifier size depends on your room area and desired air change rate. For most rooms, choose a unit with a CADR rating equal to 2/3 of your room's square footage. For example, a 300 sq ft room needs a CADR of at least 200 CFM. Use our Room Size Calculator for precise recommendations.
What is CADR and why does it matter?
CADR (Clean Air Delivery Rate) measures how much clean air an air purifier produces per minute. It's tested for dust, pollen, and smoke particles. Higher CADR means faster air cleaning. Look for units with CADR ratings that match your room size and air quality needs.
HEPA vs HEPA-type: What's the difference?
True HEPA filters remove 99.97% of particles 0.3 microns and larger, meeting strict standards. "HEPA-type" filters may only remove 85-90% of particles and don't meet official HEPA standards. Always choose True HEPA for maximum filtration effectiveness.
Do I need activated carbon filters?
Yes, if you want to remove odors, chemicals, or gases. HEPA filters only remove particles, not gaseous pollutants. Activated carbon filters absorb odors from pets, cooking, smoke, and volatile organic compounds (VOCs). Essential for complete air purification.
Operation & Maintenance
How often should I replace air purifier filters?
Pre-filters: 1-3 months (or wash monthly if washable). Carbon filters: 3-6 months depending on odor exposure. HEPA filters: 6-18 months depending on air quality and usage. Check filters monthly and replace when visibly dirty or performance decreases.
Should I run my air purifier 24/7?
Yes, for best results. Air purifiers work best with continuous operation to maintain clean air. Pollutants are generated constantly, so stopping the unit allows contamination to build up. Use auto mode or lower speeds during quiet times to balance effectiveness with noise and energy use.
Where should I place my air purifier?
Place air purifiers away from walls and furniture for optimal airflow. Avoid corners, and keep at least 3 feet of clearance on all sides. For bedrooms, place near the sleeping area but not directly next to the bed. Avoid placing near pollution sources like candles or cooking areas.
Why is my air purifier making noise?
Some noise is normal, especially on higher speeds. Check for dirty filters (reduces airflow, makes fan work harder), loose parts, or obstructed air intake. Clean or replace filters, ensure proper placement, and verify the unit is level. Most quality units operate at 24-35dB on low speed.
Performance & Effectiveness
How long does it take for an air purifier to clean a room?
Typically 30 minutes to 2 hours for noticeable improvement, depending on room size, pollution level, and air purifier capacity. A properly sized unit should clean the air 4-6 times per hour. Initial cleaning is fastest, but continuous operation maintains clean air quality.
What is ACH and how many do I need?
ACH (Air Changes per Hour) measures how many times the air purifier processes the room's air volume hourly. Recommended: 2-3 ACH for basic cleaning, 4-5 ACH for allergies/pets, 6+ ACH for severe conditions or high pollution areas. Higher ACH provides faster, more effective cleaning.
Do air purifiers help with allergies and asthma?
Yes, HEPA air purifiers significantly reduce airborne allergens like pollen, dust mites, and pet dander. Studies show 85-90% reduction in allergy symptoms with proper air purification. Choose units with high CADR for allergens and run continuously for best results. Not a cure, but very effective symptom relief.
Can air purifiers remove viruses and bacteria?
HEPA filters capture many viruses and bacteria (99.97% of particles 0.3μm+). Some viruses are smaller but often travel on larger droplets that HEPA can catch. UV-C light adds extra germicidal action. While helpful, air purifiers are part of overall health strategy, not a complete solution for infection control.
Cost & Energy
How much does it cost to run an air purifier?
Most air purifiers cost $20-60 per year in electricity. Energy usage ranges from 5-50 watts (comparable to LED light bulb). Larger, more powerful units use more energy. Look for ENERGY STAR certified models for efficiency. Filter replacement costs $50-150 annually depending on the model.
Are expensive air purifiers worth it?
Not always. Focus on CADR ratings, filter quality, and room size compatibility rather than price alone. A $200 unit with proper CADR often outperforms a $800 unit that's undersized. Expensive units may offer better build quality, quieter operation, and smart features, but basic models can be very effective.
Generic vs OEM filters: Which should I buy?
Quality generic filters can save 30-50% while maintaining performance. Check for proper dimensions, filter media specifications, and certifications. Read reviews and ensure the generic filter meets original specifications. OEM filters guarantee compatibility but cost more. Either option works if quality is maintained.
What's the total cost of ownership?
Include purchase price, annual electricity costs ($20-60), and filter replacement costs ($50-150/year). Over 5 years, total costs range from $400-1000 for most residential units. Budget models may have higher filter costs; premium models may have lower long-term maintenance needs. Use our cost calculators for specific estimates.
Health & Safety
Are air purifiers safe to use around children and pets?
HEPA and activated carbon air purifiers are completely safe for children and pets. Avoid ionizers and ozone generators, which can produce harmful ozone. Ensure units are stable and cords are out of reach. Many units have child locks and are designed with safety in mind.
Do air purifiers produce ozone?
HEPA air purifiers do not produce ozone and are safe. Avoid ionizers, plasma generators, and UV-C lights that may produce trace ozone. Always check product specifications and look for California Air Resources Board (CARB) certification, which limits ozone emissions to safe levels.
Can air purifiers help with wildfire smoke?
Yes, HEPA air purifiers are highly effective against wildfire smoke particles. Seal your home, close windows/doors, and run air purifiers continuously on high speed. Focus on one room if needed. Combined HEPA + activated carbon works best for both particles and smoke odors. Change filters more frequently during smoke events.
Will an air purifier eliminate the need for cleaning?
No, air purifiers remove airborne particles but don't clean settled dust on surfaces. They prevent particle re-suspension and reduce overall dust accumulation, making cleaning easier and less frequent. Continue regular cleaning for surfaces, floors, and fabrics. Air purifiers complement, don't replace, good housekeeping.
Technical Questions
What's the difference between air purifiers and air cleaners?
The terms are often used interchangeably, but air purifiers typically refer to units with HEPA filtration that remove particles. Air cleaners may include various technologies like ionizers or UV lights. For maximum effectiveness and safety, choose HEPA-based air purifiers over other "air cleaning" technologies.
How do I calculate the right CADR for my room?
Multiply room area by ceiling height to get volume. For 4 ACH: CADR = (Room Volume × 4) ÷ 60. For a 200 sq ft room with 8 ft ceilings: (200 × 8 × 4) ÷ 60 = 107 CFM minimum CADR. Use our calculators for precise recommendations based on your specific needs.
What fan speed should I use?
Use auto mode if available, which adjusts speed based on air quality. For manual control: high speed for initial cleaning or high pollution, medium speed for normal operation, low speed for quiet times. Most people use medium speed as the best balance of effectiveness and noise.
Can I use an air purifier in multiple rooms?
Portable units work best in one room with doors closed for maximum effectiveness. Moving units between rooms reduces efficiency. For multiple rooms, consider several smaller units or a whole-house air purification system integrated with HVAC. Our multi-room calculator helps determine the best approach.
Need More Help?
Use our calculators to get personalized recommendations for your specific room and air quality needs.