Smoke + Mirrors: Fog Effects And Asthma

What do concerts, some plays, and haunted houses have in common? They often use some sort of fake fog effect to make them look cooler, or more spooky, or more dramatic. While I’ve heard of people having asthma symptoms triggered by these sort of fog effects, I haven’t really experienced it myself. That’s because how, and if, these sorts of fog effects trigger asthma is massively based on what is producing the fog itself. Note, as well, that “smoke machines” do exist—though probably not commonly operated by the public—and those are a whole other story all together.

The American College of Allergy, Asthma and Immunology notes that extreme exposure to the “fog” created by fog machines can cause eye irritation, voice/throat symptoms and even asthma- or bronchitis-like symptoms in those without asthma.¹ Typically, this is only seen when long-term exposure is experienced. For people with asthma, it is recommended that the safest option is a machine that turns “liquid air" into “fog”, as oxygen levels in the space are not decreased.¹ Fog machines commonly create haze by releasing glycol. Michigan Institute of Technology (MIT)’s music and theatre program materials note that in no way are fog fluids used today toxic, nor are they carcinogenic or induce asthma symptoms². It is also noted that unless you are within 3 feet of the largest fog machines on a Broadway stage, the glycol level released will not be markedly increased².

If you are in close proximity, there may be certain fog inducers that trigger your asthma, and some that do not. Unfortunately, just like everybody’s asthma is different, the only way to find out is to see what happens. If you are concerned, it’s always a good idea to speak with your doctor about pre-medicating with a bronchodilator inhaler when you are going to be in situations that may trigger your asthma, like being near a fog machine. Wearing a mask is also recommended for people who work closely with these devices. Dry ice may also be used to produce “fog”, and—like some other compounds—decreases the amount of oxygen in the air if breathed in directly.³ Be cautious about dry ice fog as well, even though you may not think about it as an asthma trigger. The best way to stay safe, is to inquire about how the fog effect is created—if, like the American College of Allergy, Asthma and Immunology states, the fog is created from a liquid air source, it is probably safe—liquid air is comprised of 79% nitrogen and 21% oxygen, which is the same as room air and thus safer to inhale.⁴

The take home message here is that you are most likely safe if you keep a distance from fog machines—after all, the effect is best enjoyed when you get the big picture! But, during certain activities, it may be important to be mindful of the effects that fog effects can have on your asthma, so that a night of entertainment—whether around Halloween, in a laser tag field, or another indoor attraction using fog effects to create the illusion of being in a haze! If you’re concerned… step out of the area for some fresh air.