Can you use a Portable AC when it’s Smoky outside?

You can only use some portable ACs when it’s smoky outside, whether that’s because of wildfires or due to an industrial area nearby.

In this article, we’re going to check which air conditioners are OK to be used and which aren’t.

Quick answer: You should not use a single-hose portable AC when it’s smoky outside. However, you can always use dual-hose portable ACs, window ACs and split ACs, as these don’t suck in outdoor air.

Air conditioner typeCan you use it when it’s smoky outside?
Single-hose portable ACno
Evaporative cooler (outdoor connected)no
Dual-hose portable ACyes
Window ACyes (ensure no ‘Fresh Air’ mode is enabled)
Split ACyes

As you can see, you can use all air conditioner types, except single-hose portable air conditioners and outdoor-connected evaporative coolers.

So, if you really need a portable AC model, then I highly suggest getting a dual-hose AC.

Further down in this article, I will recommend you a good dual-hose AC!

Why can’t you use a single-hose portable air conditioner when it’s smoky outside?

A single-hose portable air conditioner has just one hose. This hose is used to expel the hot air outside.

But blowing air outside creates a negative pressure inside your room, which, in turn, sucks air from other places, such as other rooms, and also from outdoors.

A single-hose portable air conditioner sucks in outdoor air and causes smoke to enter your room.

The worst thing about single-hose air conditioners during smoky times is that you can’t really do anything to prevent smoke from entering your room. Technically, a portable air conditioner will force outdoor air into your room.

“Avoid using an evaporative cooler or portable air conditioner with a single hose in smoky conditions unless there is a heat emergency. Using these devices can result in more smoke being brought inside.”

EPA Indoor Air Quality guide

This is not only a drawback of single-hose portable units during smoky times, but it is also a general technical issue.

The negative pressure a portable air conditioner creates sucks in warm air from other places into your room. Single-hose ACs even suck in the cold air they just produced and blow it outdoors.

So, there are a lot of technical problems with single-hose portable ACs.

Recommended air conditioner for smoky environments

If you live in an area that’s frequently exposed to smoke, such as a wildfire area, or an industrial area, then you can use the following air conditioners.

Dual-hose portable air conditioner

Dual-hose portable air conditioners are safe to use when it’s smoky outside. Single-hose units are not safe to use and will suck the outdoor smoke into your room.

This Whynter dual-hose portable air conditioner (click here to view it on amazon) will never suck in any outdoor air, and therefore, no smoke.

The reason is that it’s a dual-hose system. In a dual-hose portable air conditioner, one hose sucks in air from outside (instead of inside), uses the outside air to absorb heat from the refrigerant, and then blows the outside air outside again.

So, the smoky air from outside will never enter your room with a dual-hose portable AC.

I recommend getting a dual-hose air conditioner if you absolutely need a portable air conditioner, otherwise, you can also stick to the classic air conditioner choices.

Window air conditioner

Window air conditioners are safe to use when it’s smoky outside.

Most window air conditioners have just the same advantages as dual-hose portable air conditioners: They don’t suck in any outdoor air.

Some window air conditioners might have a ‘Fresh Air’-mode, which, when enabled, causes the air conditioner to suck in smoky air from outdoors. If your window AC has such a setting, then you can simply disable it and it will run on indoor air only.

“If your HVAC system or window air conditioner has a fresh air option (meaning it pulls in air from the outside), turn it off, close the intake, or set the system to recirculate mode.”

EPA Indoor Air Quality guide

However, since it does not need two long hoses to blow heat, there are no insulation problems: 

With portable air conditioners, the heat that’s supposed to leave your room partly reenters your room, because the hoses are made of cheap plastic and don’t insulate well.

A window air conditioner fixes this problem by not having any long paths for the air to take.

Because of that, they are more efficient than portable units!

Split air conditioner

Split AC units are safe to use when it’s smoky outside.

A split AC unit works technically the same as a dual-hose portable AC or a window AC. All of these don’t suck in air from the outdoors.

They suck in indoor air and blow that same air back into your room once it’s cooled.

Do air conditioners filter smoke?

Window air conditioners, split ACs and dual-hose portable air conditioners do not suck in outdoor air. So, there is no need to filter smoke.

A single-hose portable air conditioner or an evaporative cooler will suck in outdoor air, but won’t filter the smoke.

In general, single-hose portable air conditioners are cheaply made, and the air filter is one aspect of the system where manufacturers save money.

I would not trust them to put a good air filter in the air conditioner.

So, if you want filtered air with an air conditioner, then you should insert your own HEPA filter.

Still, I would not recommend running the air conditioner when it’s smoky outside. Because if something goes wrong, then you will have a smoky indoors.

And you won’t be able to get rid of that!

Will evaporative coolers filter smoke?

Evaporative coolers won’t filter smoke, unless you installed your own certified HEPA filter. And even then, there’s the risk of the filter not being fully sealed and causing smoke to get sucked into your indoors.


I recommend not running any single-hose portable air conditioners or outdoor-connected evaporative coolers when it’s smoky outside (during a wildfire or nearby an industrial area).

Instead, you should buy a proper dual-hose air conditioner, a window AC or a split AC.

All of these air conditioner types don’t suck in any outdoor air and you can safely run them when it’s smoky outside.