The short answer for a small bedroom or home office
If you are choosing a bedroom air purifier for cat dander and pollen, the safest rule is simple: buy enough clean-air delivery for the room, then run it on a quiet speed you can tolerate every day. For a small home office or spare bedroom around 1,000 to 1,200 cubic feet, the Coway Airmega 150 can be enough if the room is closed off and you mainly want steady allergy support. The Coway Mighty AP-1512HH is the better buy if you want more headroom, faster cleanup after the cat has been in the room, or quieter performance at a lower fan speed.
The difference is not that one is “good” and the other is “overkill.” It is that air purifiers work by moving air repeatedly. A slightly larger purifier on medium is often easier to live with than a smaller purifier forced to run high whenever pollen, dust, or pet dander spikes.
How to size an air purifier for cat dander and pollen
Ignore marketing room-size claims until you check CADR, which stands for clean air delivery rate. CADR is the practical number that tells you how much filtered air the purifier can move. For allergies, aim for roughly four to five air changes per hour in the room you actually use. That means a purifier sized for a much larger room on paper may simply give you better real-world cleaning at a quieter speed.
Cat dander is light, sticky, and constantly reintroduced when a pet walks through the room. Pollen can enter on clothes, hair, windows, HVAC leaks, and pets. A purifier helps most when it runs continuously with the door mostly closed, placed away from walls and curtains, with replacement filters changed on schedule.
Pick 1: Coway Airmega 150 — compact, quiet, and enough for smaller rooms
The Coway Airmega 150 is the neater choice for a smaller bedroom, office, nursery, or spare room where space and looks matter. It uses a pre-filter, deodorization filter, and Green True HEPA filter, with a washable pre-filter that slides out easily. That matters in pet homes because the pre-filter catches larger dust and hair before it reaches the HEPA layer.
Best for: small bedrooms, home offices, renters, and light-to-moderate pet dander
Useful feature: easy pull-out washable pre-filter
Room fit: best when the room is modest in size and the door is usually closed
Main caveat: less airflow headroom than the larger Mighty AP-1512HH
The Airmega 150 is especially appealing if you do not want a purifier that visually dominates the room. For a 10 x 12 bedroom or a compact office, it can run quietly in the background and keep fine particles down over time. If the room is closer to 150 square feet with normal 8-foot ceilings, it is a sensible, non-bulky pick.
Where it becomes less ideal is a larger room, an open doorway, or a situation where the cat spends hours in the space and allergy symptoms are noticeable. In those cases, the smaller purifier may need higher fan speeds more often, which can erase the comfort advantage.
Pick 2: Coway Mighty AP-1512HH — better headroom for allergy control
The Coway Mighty AP-1512HH is the more practical allergy-focused choice for many bedrooms because it has stronger airflow in a still-manageable body. It is widely used for bedrooms, apartments, pet rooms, and home offices because it balances CADR, filter availability, energy use, and long-term ownership cost well.
Best for: cat dander, pollen, dust, larger bedrooms, and faster particle cleanup
Useful feature: air-quality indicator with auto mode
Room fit: better for rooms where you want more cleaning power without running high all day
Main caveat: larger footprint and a more appliance-like look
For many buyers, the Mighty is the smarter long-term pick even in a room that technically does not require it. You can run it on a lower speed most of the day, bump it up after vacuuming or when pollen is high, and still have extra capacity. That headroom is useful with pets because the particle source is ongoing rather than a one-time event.
Airmega 150 vs AP-1512HH: which one should you buy?
Choose the Coway Airmega 150 if the room is small, you care about a compact design, symptoms are mild, and you are willing to keep the door closed while it runs. It is a clean, simple bedroom air purifier for people who want allergy support without buying a larger unit than the room visually needs.
Choose the Coway Mighty AP-1512HH if the room is closer to a larger bedroom or home office, if a cat spends a lot of time there, or if pollen and dander are a real trigger. It is the better “buy once and do not worry about sizing” option because extra CADR gives you more flexibility.
What about odors?
Both models include carbon-style odor filtration, but neither should be bought primarily as an odor machine. Thin carbon filters can reduce mild pet smells or stale-room odors, but they are not the same as a heavy activated-carbon purifier built for smoke, VOCs, or strong cooking smells. For cat dander and pollen, HEPA performance and airflow matter more than deodorizing claims.
Setup tips that make either purifier work better
Run it continuously: allergy particles return quickly when the purifier is off.
Place it in open air: keep several inches of clearance around the intake and outlet.
Clean the pre-filter often: pet hair can reduce airflow if it builds up.
Do not hide it behind furniture: airflow matters more than perfect decor.
Pair it with cleaning: vacuuming, washing bedding, and brushing pets all reduce the particle load.
Verdict
For a small closed bedroom or tidy home office, the Coway Airmega 150 is a reasonable, attractive air purifier for cat dander and pollen. For most allergy-sensitive buyers, the Coway Mighty AP-1512HH is the safer recommendation because it gives more airflow headroom without jumping into a huge or expensive machine.
If you are unsure, size up. A larger purifier can run quietly on lower speeds, but a smaller purifier cannot create extra airflow when the room, pet load, or pollen season demands it.