Last edit: 09/29/15

Re: Air Purifier for Cat Litter Box Odor

A Reader writes:

Hi again Ed.

While not strictly your area,

I was wondering if you would have any helpful advice regarding effective cat litter box odor reducing devices?

Like air purifiers I'm finding there is a large variety of makes and models out there, boasting all sorts of seemingly implausible claims.

Any tips to help me find my way through the maze?

Ed's Reply

Hey Reader;

I cannot claim to be an expert on cats, although I always have at least one semi-wild cat living in a shed on my back acre.

My rural cul-de-sac seems to attract city folks with unwanted pets to drop off.

The current occupant is a mature female I call "Kat."

I do not love cats, but have come to respect Kat - she survives on her own, with just a little help from me, in an environment where hundreds of her kind have perished.

My country cul-de-sac seems to attract folks wanting to discreetly abandon pets.

Research shows that "cat not using the litter box" is the top reason for for trips to the vet and feline abandonments.

In my opinion, the issue goes beyond unsavory odors - a dirty catbox is a health hazard for the entire household, including the cats.

Cat box odor is one of the strongest smells, and toughest to remove with air purifiers.

While many vendors pretend their air purifiers "eliminate" cat odor, the fine print usually says "reduces."

All air purifiers will struggle with this notorious continuous source emission.

Chemicals in cat urine will build up over time, saturating carpet, interior fabrics, and furniture.

Anyone living in real estate they plan to sell needs to realize that pet odor is a major deal killer.

So the best approach is to attack this problem at the source before considering air purifier choices.

Cats in the wild would never make the mess they are forced to make indoors.

Wild felines excrete wastes along the periphery of their territory, far away from dens and nourishment sources.

A clean litter box is crucial to an indoor cat's health. If the smell is bothering human noses dulled by civilization, cats completely despise it.

A multi-cat household should have at least one box per cat.

Odor is nature’s way of signaling the presence of dangerous decomposer bacteria.

Bacteria in a poorly maintained cat litter box cause most of the odor, and serious health issues for both pets and humans.

Cat feces, especially from indoor-outdoor felines, can carry the parasite Toxoplasma, associated with birth defects in humans.

Women who are pregnant or may become so should not handle cat excrement.

Litter Box Maintenance

The key to controlling cat box odor is in fastidious maintenance.

Early and frequent cleaning is absolutely required - time is of the essence.

Once the urine and feces have been allowed to set, decomposer microorganisms begin emitting smells.

It is much easier to prevent an odor situation than to remediate with an air cleaner.

But litter box cleaning is an often delayed or avoided task, as evidenced by the cascade of new products claiming to lessen the burden on cat owners.

In my opinion, the worst of these products are enclosed/hooded boxes with ventilation or filters.

These keep the mess out of people's sight, but it doesn't go away.

If waste material in the litter box is sufficient to need exhaust air filtering, the cat is forced to walk through accumulated excrement.

This causes "tracking," a contributing cause of odor, and a feline/human health issue.

Particles of contaminated litter, dust, and feces accumulate between the cat's pads and claws, and on their fur.

After the cat visits the litter box, these pollutants are be tracked throughout the home.

Cats hate all dirt, and will lick their paws to "clean," then lick their fur.

After grooming, cats will want social interaction - purring and petting.

Many cat people place a small mat or piece of carpet by the box, and specialty products are marketed to capture as much tracking residue as possible.

So changing all the litter at least weekly, and more often with some cats, then washing the box out, with plain unscented soap and water is the first step in improving the indoor pet environment. Twice a week is recommended.

Never use chlorine-based cleaners on the box.

After a time, the plastic box accumulates chemicals and needs to be replaced.

Some report box life extension with vinegar soaking when cleaning.

Cleaning the area around the litter box will reduce over-spray and digging debris issues.

Deeper litter keeps urine from seeping to the bottom.

Many cat odor issues are caused by cheap or improper litter.

Changing to high-quality clumping/scoopable litter is a first step.

Clumping litter, which forms scoopable balls of both urine and feces, is best for reducing cat litter box odor.

Using a scoop with gaps which match the size of the uncontaminated litter granules, collect all the balls very frequently and dispose.

After each scooping, top off the litter.

Make sure that litter itself is not introducing health issues for both cats and humans.

Traditional clay litter had issues of fine dust emissions - any litter should be non-dusting.

Cat Odor: Ammonia

Cat odor is primarily urine odor, assuming fecal material has not been left untended. Cats urinate more often than they defecate.

Male cats have stronger urine odor, used to mark their territory with scent. Females in heat also secrete extra scents.

Cat urine contains high levels of ammonia, a very smelly byproduct of the high-protein diet cats need.

Noses are exquisitely sensitive to ammonia's odor because it warns us away from dangerous excrement.

Many air purifiers have limited ability to capture ammonia.

Time to feed the Cat

Quality cat food can help reduce cat box smells.

Healthy people, and pets, just naturally smell better.

Cats now suffer from all the modern human aliments; obesity, irritable bowel syndrome, diabetes, cancer, kidney failure......

Most inexpensive pet food products are outright toxic.

Fish-based cat food is made from fish unsuited for human consumption due to high-and-rising Mercury levels.

Likewise, meat unfit for humans is channeled to pet food processors.

Much "cat food" is also inappropriate for feline digestion, which is designed for a meat-based diet with a few fruits and greens.

High carbohydrate grain-based foods are economical, but kill cats even faster than they kill humans.

Felines lack enzymes for digesting carbs, leading to microorganism overgrowth in the bowel.

In the vernacular - stinky poop and pee.

Older cats become deficient in digestive enzymes and develop feline diabetes.

This is why one catbox deodorizer, "Nature's Miracle Litter Treatment," is composed primarily of enzymes.

Likewise, Bi-Odor Waste Deodorizer is a feed/water supplement consisting of amino acids (predigested proteins) and enzymes.

So changing your cat's diet to a higher quality protein-rich/low-carb feed ration could help the litter odor issue.

Cats on dry food diets may become dehydrated, concentrating their urine.

My Kat will come to me for help ONLY when the dry summer heat of central Texas makes her very thirsty.

In the CatBox

Attacking the odor at its source starts with unscented litter.

Scents and fragrances just cover the smell, do nothing about the health consequences, and deeply annoy and stress cats, who rely on smell as their primary sense.

I am shocked when I read of folks burning candles or incense to mask litter box smells.

There are entire pages on this site dedicated to the economic and health risks of indoor burning. Spray deodorizers and "air fresheners" just make things worse.

Many sprinkle baking soda on the bottom of the box to absorb odors.

The first thing I'd try is activated carbon, applied right at the box.

This will be much cheaper than replacing air purifier filters.

There are numerous sources for carbon. Some cat owners report using regular barbecue charcoal (without lighter fluid) in the cat box with success.

I recommend granulated carbon designed for air cleaners, to avoid powder emissions.

Why not add granular carbon to the litter? I have never tried this but apparently cats are not offended by the charcoal mentioned above.

Here is my favorite activated carbon supplier. E.L. Foust can deliver three pounds of carbon pellets, which should last a couple months, for maybe $20.

E. L. Foust carbon refills

Foust can supply other adsorbents, including zeolite.

A product I like is the inexpensive Mosso air cleaning bag, available starting at 2 for ten bucks:

Mini Moso Air Purifying Bags at

Folks needing more detail can see my Mosso Bag Review, based on the bigger bag but the issues are similar;

Moso Natural Air Purifying Bag Review

Other pet owners report using citric acid crystals, purchased in the grocery store canning aisle, as an odor adsorbent in the litter.

Air Cleaners for Litter Box Smells

An effective air purifier needs to have a filter that is specifically designed to remove urine odor.

Ammonia saturates absorbents quicker than other chemicals, leading to higher filter costs in pet situations than normal households.

So I advocate the methods listed above, even when an air purifier is installed near the cat box.

If the odoriferous litter box can be placed in a small room, within 6 feet of an electrical outlet, the $25 True Air from Hamilton Beach with optional pet odor filter, is worth a try:

Hamilton Beach True Air Odor Eliminator at

There are several electronic odor eliminators which may work on odors but have health issues of ozone and "oxyions."

Most under-$200 air cleaners won't carry enough carbon to catch litter scents for long.

Plasma-ion machines like the Sharp Plasmaclusters and Winix Plasmawaves could work economically, some have odor sensors.

Moving up the price chain, the $500 Austin Air Pet Machine is specifically designed for ammonia adsorbtion.

Vendors quote the Pet Machine as having 6.5 lbs. of Activated Carbon, 7.5 lbs. of Zeolite and 1 lb. of a product called Ammonasorb.

Calgon Carbon, which produces Ammonasorb, lists Phosphoric Acid (H3PO4) at 20% by weight.

The best cat odor air cleaner is most likely the premium-priced ($1,200.00) IQAir GC AM, designed to capture ammonia.

The IQAir AM sports 17 lbs. of activated carbon and potassium permanganate. But the price is higher than most catbox situations warrant, and with expensive filter replacements, I'd try all the above ideas first.

No air cleaner is a substitute for regular litter box maintenance, even if odors are eradicated.

You can browse

Air Purifiers at

More than the fog comes on little cat feet.

Best wishes,



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