We measure how much noise the purifiers make, add up their long-term costs for energy consumption and replacement filters, consider the ease of operation and maintenance, the presence or absence of distracting lights, the simplicity of the controls, and their physical size and aesthetics
You can find smoke-free and tobacco-free products as well products that are more discreet and convenient to use than traditional cigarettes
Here is the number that matters: a thin carbon mat weighing 150-200g, which is what you find in most sub-$400 HEPA + carbon air purifiers, has a finite adsorption capacity measured in grams of pollutant
Excessive heat can cause batteries to degrade rapidly and potentially become dangerous
The limited strengths available may also be a disadvantage - you can double up and use two pieces if necessary, but with only 2 strengths available to buy, you are still limited in terms of controlling the nicotine dose