Why are Himalayan salt lamps bad for air quality?
Again, two words: negative ionization.
If you ever hear the words “ionization” (in one form or another) and “air purification” in the same sentence, you should run in the opposite direction.
In the context of air purification, negative ionization happens when negatively charged particles attach themselves, or “charge,” pollutant particles in the air, effectively removing them from ambient air by causing them to stick to nearby surfaces.
This phenomenon also occurs in nature – know that distinct smell in the air after a thunderstorm? That’s the result of “atmospheric space charge” as air ions are generated by the electric fields of storms.1 Many air purifiers and purification devices sold in stores, including Himalayan salt lamps and a variety of “air ionizers,” artificially produce high voltage to achieve this same effect.
The problem with negative ionization, though, is that it doesn’t actually remove pollutants from your indoor air – it just causes the particles to adhere themselves to nearby surfaces, where they’re easily stirred up by indoor activities like dusting, vacuuming, and ventilation.
Charged particles can also stick to your respiratory tract, where charged particles can settle in your windpipe and lungs and cause even more harm that if they’d just remained in the air. Studies show that these particles can penetrate deep into your respiratory system and cause both heart and lung conditions.2
The average, nightstand-sized Himalayan salt lamp generates only a small number of negative ions into the air, so you may not notice any tangible change in your air quality or health, at least immediately. But these lamps can be huge: you can buy salt lamps that weight up to 300 pounds for thousands of dollars, and their ionization effects may have a more noticeable effect on your air, especially if you live in an airtight, energy-efficient home in which indoor pollutants have a much harder time getting out.
And negative ionizers have another dark secret: they can also create indoor ozone (O3).
There are two main types of ozone:
- Stratospheric ozone: A layer of ozone occurs naturally several miles up in the atmosphere, where it protects the surface of the earth (and people’s skin) from ultraviolet (UV) radiation from the sun.
- Tropospheric ozone: Also called ground-level ozone or smog, ground-level ozone tends to develop when heat from sunlight reacts with chemicals near the ground, many of which are produced by emissions from vehicle exhaust and factory smoke.
Negative ionization can generate tropospheric ozone indoors. While stratospheric ozone has no interaction with us in the lower atmosphere, ground-level ozone is far more harmful when it builds up to high levels. And perhaps one of the starkest examples of ground-level ozone is one that millions of us know very well – the smog that forms in major cities during rush hour.
If you live near a freeway, dense urban center, or even at a high elevation where you can see the area around an urban area. A few hours or less after rush hour begins and the sun begins to rise, you’ll start to notice a visible layer of haze build up. This is ground-level ozone, and even though it’s a typical feature of modern life, extensive research shows that it causes a plethora of immediate symptoms, including:
- Trouble breathing
- Stuffy nose
- Tingling in arms and legs
Further research suggests that ozone is also responsible for long-term health problems, such as asthma, heart disease, and lung disease. Emerging studies on rats also suggest that ozone could cause seizures and blindness.
So even though you may not get rush-hour levels of ozone in your home from a salt lamp, indoor ozone buildup can indeed cause some disruptive health effects if you don’t follow best practices for good Indoor Air Quality.
So what’s so special about Himalayan salt?
So how did someone come up with the idea that Himalayan salt lamps have any health effects at all?
The story stretches back millennia. Truly authentic Himalayan salt comes from the Khewra salt reserves in the Punjab region of Pakistan. Salt mined here is thought to be millions of years old and contain numerous minerals.
Salt lamps have been proposed for use in treatments for conditions like chronic obstructive pulmonary disease (COPD) because of their purported therapeutic effects on your respiratory system. This treatment even has a clinical term: halotherapy, based on an ages-old respiratory treatment technique known as speleotherapy. First used in Eastern Europe, speleotherapy consists of spending time in a salt cave, where four environmental conditions are thought to help reduce symptoms of respiratory illness:5
- Stable air temperature
- Moderate to high humidity
- Presence of aerosol elements, such as sodium, potassium, and magnesium
- Lack of airborne pollutants
Halotherapy takes the notion that salt cave environments are good for respiratory health by having people inhale small amounts of salt particles that are released into the ambient air of a controlled room to “reproduce” a salt cave’s microclimate. But there’s no conclusive evidence that either speleotherapy or halotherapy actually relieve respiratory symptoms.6
Take the claims with a grain of…well, salt
So here’s the takeaway: We’re not saying you shouldn’t get a Himalayan salt lamp. Their dim glow can be quite soothing at night when you’re trying to fall asleep.
But they don’t purify air. And “air purifiers” that emits ions and ozone may make your indoor air quality worse, introduce new health problems, and exacerbate existing ones.