Air purifiers and dehumidifiers minimize allergens in the room, making it easier for those suffering from allergies and asthma. An air purifier circulates air through a filter that traps air-borne pollutants and irritants like dust, smoke and pollen. A dehumidifier sucks in moisture and reduces the humidity levels in the air, killing mold and microbes that thrive in moisture.
Comparison chart
 | Air Purifier | Dehumidifier |
|---|---|---|
| Purpose | To circulate and filter the air by trapping dust, smoke and other allergens | To reduce the moisture content in the surrounding area. |
| Humidity levels | Can vary | Used where humidity is greater than 50% |
| Types | Filter, Ionizing, Ozone generators, Adsorbents, UV light | Mechanical /refrigerative, Air conditioners, Adsorption/desiccant, Electronic, Ionic membrane, Makeshift |
| Application | Beneficial to allergy sufferers and asthmatics as they reduce or eliminate dust, second-hand tobacco smoke and other air-borne allergens. | Recommended to alleviate allergy by eliminating mold, dust mites and mildew from the air. |
Function
An air purifier circulates air through a filter which removes air borne pollutants, like dust or smoke particles, and even pollen, which a dehumidifier cannot. An purifier may prevent mold build-up as it removes the spores from the air. However, because it cannot control humidity levels in a house, excessive moisture can cause mold to return. The video below deconstructs a humidifier to demonstrate how it works:
A dehumidifier's primary function is to eliminate excessive moisture from the air and bring down a room's humidity levels. While this device does not clear or filter air, it does help remove allergens, like mold and dust mites, which thrive in a moist or humid environment. With a humidity level less than 50%, these sources of allergies and asthma wither and die. This is how a dehumidifier works:
Types
Types of Dehumidifiers
Two types of dehumidifiers are typically found in the marketplace: warm mist and cool mist. Regardless of mist type selected, both affect moisture level in the air and lower the level of humidity. Other types include:
- Mechanical /refrigerative is the most common type and works by drawing moist air over a refrigerated coil with a small fan. Condensed air is collected, and is effective at higher ambient temperatures where the relative humidity is over 45%.
- Air conditioners inherently act as dehumidifiers.
- Adsorption/desiccant is special humidity-absorbing material, moving along a belt, which is exposed to the lower-temperature air being conditioned. Air is reused after being heated to remove humidity, typically at levels of 35% or lower.
- Electronic dehumidifier uses a Peltier heat pump to generate a cool surface for condensing the water vapor from the air. It has no moving parts and hence is quieter. But it has low energy efficiency and this design is used for smaller humidifiers.
- Ionic membrane - a specialized type of ionic membrane can be used as an ionic pump to move humidity in or out of sealed enclosures at the molecular level. The device is mainly used in industrial areas with fuel cell, chemical, or water improvement application.
- Makeshift - Window air conditioner units that operate similar to mechanical/refrigerative dehumidifiers. Makeshift dehumidifiers function by sending its heat exhaust back into the room.
Types of Air Purifiers
The types of air purifiers include:
- Filter air purifiers, which use a HEPA (High Efficiency Particulate Air) filter or an ULPA (Ultra-Low Penetration Air) filter to circulate air and trap dust particles.
- Ionizing purifiers use corona discharge, a small but powerful electrical field which creates and uses oppositely charged particles to collect together and settle out of the air.
- Ozone generators which work like ionizing purifiers by changing the oxygen molecules in the air into ozone.
- Adsorbents use an adsorbent material to take care of odors, fumes and chemicals in the air.
- UV Light which renders some micro-organisms sterile through ultraviolet radiation.
Best Air Purifiers for Wildfire Smoke
The air quality index, which you can check for your area on AirNow.gov, deteriorates severely when there are wildfires in a neighboring area. Sometimes, depending upon their intensity, wildfires even affect air quality in areas that are quite far away from the fire. e.g., wildfires in British Columbia (Canada) affecting air quality in Seattle. An air purifier is essential in such circumstances because the air quality is hazardous to health, especially for vulnerable populations like those with COPD or other respiratory problems.
So what are the best air purifiers for wildfire smoke? According to Consumer Reports, some of the best air purifiers for wildfire smoke — which incidentally are not all that different from the best purifiers overall — are:
- Honeywell HPA300 (less than $250)
- Blueair Blue Pure 211+ (less than $300)
- Samsung Cube ($500-$750)
- Blueair Classic 605 (around $800)
Health hazards of Air Purifiers
Ozone production is typical for air ionizing purifiers. Ionic air purifiers can produce ozone as an additional feature to eliminate odor. Although high concentration of ozone is dangerous, most air ionizers produce low amounts (<0.05> ppm). Many air purifiers generate some ozone, and in the presence of humidity, small amounts of nitrogen oxide.
The noise level of a purifier can be obtained through a customer service department
Maintenance
Maintaining dehumidifiers requires cleaning all its coils and buckets periodically, and also checking these coils for frost, to improve efficiency.
Air purifiers can be maintained by replacing the filter every 6 months. If the humidifier has plates, they should be washed once a week. To clean the plates, take them out of system and place them in the dishwasher or submerge them in the sink.
How and Where to Buy
After you've decided which appliance is right for you, the next step is what to look for. The Amazon Best Sellers lists for air purifiers lists the most popular air purifiers in a wide price range. The video below is a guide to buying air purifiers:
Amazon's Best Sellers list for dehumidifiers is a good starting point to find one that suits your home, budget and preference. A guide to buying dehumidifiers is in the video below:
Cool-mist 
Humidifier 
Bronchitis 
Humidifier 
Upright 
Allegra
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