14.09.2026

Air purifier or humidifier? What’s the difference, and which do you need?

The air in your home can make a real difference to how comfortable it feels. Dust, pollen, pet hair, fine airborne particles and household odours can be present throughout the year. Autumn and winter bring another consideration: indoor humidity can drop when the heating comes on. So, do you need an air purifier or a humidifier? Although the two are often discussed together, they serve different purposes. An air purifier can help reduce certain airborne particles and, depending on its filtration system, some gaseous pollutants. A humidifier adds moisture to the air, helping to make an overly dry room feel more comfortable. The right choice depends on what you want to address in your home.

How can an air purifier improve the air in your home?

Indoor air can contain a wide range of tiny particles from sources both inside and outside your home. These include dust, pollen, fine particulate matter and particles released during everyday activities. The World Health Organization (WHO) pays particular attention to PM10 and PM2.5 in its air quality guidelines. The latter are especially relevant when assessing air quality because of their exceptionally small size. A suitably chosen air purifier can help reduce airborne particles by continuously filtering the air. The process is straightforward: the appliance draws in air from the room, passes it through one or more layers of filtration, then releases the filtered air back into the space.

Modern air purifiers can combine several types of filter. High-efficiency particulate filters, such as HEPA filters, capture fine particles, while activated carbon filters can help reduce certain gases and odours. According to guidance from the US Environmental Protection Agency (EPA), a particle-filtering appliance with a high clean air delivery rate (CADR) can be a useful addition to other measures for improving indoor air quality, provided it is suitable for the size of the room. CADR indicates the volume of filtered air an appliance delivers over a given period when removing particles. The larger the room, the more important it is to choose a model with sufficient capacity and an appropriate CADR. The EPA therefore recommends considering both room size and CADR when choosing an air purifier. This type of appliance can be particularly useful if dust, pollen or pet hair are a recurring concern, or if you simply want to pay closer attention to the air in your home. Regular air filtration can complement ventilation and routine cleaning as part of your approach to maintaining indoor air quality.

When might you need a humidifier?

A humidifier adds moisture to the air, increasing its relative humidity. This can be particularly useful during the colder months, when the heating is on and the air indoors may feel drier. Low humidity can feel uncomfortable and may contribute to dryness of the skin, lips, nose or throat. The EPA’s guidance on home humidifiers identifies easing the discomfort associated with dry air as one of the common reasons for using them.

When adding moisture to the air, balance matters. The aim is to create a comfortable indoor environment, rather than to raise humidity as much as possible. The EPA recommends avoiding sustained relative humidity levels above 50% at home, as excess moisture can encourage mould and other biological contaminants to grow. A humidity meter, also known as a hygrometer, can help you keep track of conditions more reliably than judging by feel alone. Research also suggests that there is no single ideal humidity level for every building, season and situation. It therefore makes sense to consider the reading alongside the conditions in your home and your own comfort. Cleaning and maintenance are equally important. The EPA stresses that the water tank and humidifying unit should be cleaned regularly in line with the manufacturer’s instructions.

Could your home benefit from both?

If your main concern is airborne dust, pollen, pet hair or other fine particles, an air purifier may be the more relevant choice. If you measure low humidity during the colder months and the air feels dry, a humidifier may be useful.

Both issues can occur at the same time. In autumn and winter, you may spend more time indoors with the heating on, while dust, pollen, pet hair and other particles remain in the air. In these circumstances, you may benefit from both air purification and humidification. A combined appliance offers a practical way to bring the two functions together.

Richter AP4: air purification and humidification in one appliance

The Richter AP4 air purifier and humidifier combines several stages of air filtration with a built-in humidifying unit. It offers a convenient option if you want to address both airborne pollutants and low humidity at home. Its filtration system includes a pre-filter, catalytic filter, activated carbon filter, antibacterial cotton layer and HEPA13 filter, complemented by UV-C and ioniser technology. Each filter has a different role. The pre-filter captures larger debris, hair, fluff and pet hair, while the activated carbon filter helps reduce certain odours and gaseous substances. The HEPA13 filter captures fine particles.

This arrangement allows different filters to target different substances in the air. The EPA’s guidance likewise explains that removing particles and gases may require different technologies: HEPA filtration is used for particles, while activated carbon can help remove certain gases.

The AP4’s built-in humidifier has its own filter and runs on tap water. Once the tank is filled, it humidifies the air automatically, with moisture output varying according to the selected fan speed. Having both functions in one appliance saves you having to find space for two separate units in the same room.

According to the manufacturer, the appliance’s smart sensors continuously monitor air quality and adjust the fan speed accordingly in automatic mode. The AP4 also offers manual operation, a timer and a night mode, and can be controlled via an app over Wi-Fi.

Performance is another key consideration when choosing a model. The AP4 has a stated CADR of 488 m³/h for PM2.5 particles, and the manufacturer recommends it for rooms measuring 34–58 m². At low fan speed, the stated noise level is no more than 38 dB(A). These figures help you assess whether the appliance is suitable for your space. As the EPA advises, an air purifier’s clean air delivery rate should be appropriate for the size of the room in which it will be used.

A more comfortable home takes more than one measure

A modern air purifier and humidifier can help you manage the air in your home, but it works best as part of a broader routine. Regular ventilation, thorough cleaning, reducing sources of pollutants, maintaining filters and monitoring humidity all have a part to play. The EPA recommends a similar approach: reducing pollution at source and ensuring adequate ventilation, with air filtration as an additional measure.

The WHO’s air quality guidelines also highlight the importance of reducing fine airborne particles to support healthier air quality. Humidification calls for the same care and attention. Check the room’s humidity, clean the humidifying unit regularly and avoid adding too much moisture. If you frequently notice heavy condensation on windows or damp patches on walls and other surfaces, reduce humidifier use.

Choose according to your home’s needs

An air purifier and a humidifier perform different jobs, so either or both may be useful in your home. Air purification helps reduce certain airborne particles and pollutants, while humidification adds moisture when the air is too dry.

If you are dealing with just one of these issues, choose an appliance to suit. If both air quality and low humidity are concerns during the colder months, a combined model may be more convenient. The Richter AP4 brings both functions together, using several stages of filtration to clean the air and a built-in humidifying unit to help make your home more comfortable.

Discover the Richter AP4 air purifier and humidifier, and bring air filtration and moisture control together in one practical appliance.