Experts warn: a dirty car air conditioning filter in winter can accumulate fungi and bacteria, causing allergies, fatigue, and even loss of attention while driving.

Written by Andriely Medeiros de Araújo

Published on 13/04/2026 at 09:42

Updated on 02/05/2026 at 16:57

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The air conditioning filter is essential in winter to prevent respiratory diseases, improve indoor air quality, and ensure comfort. Learn when to change it and how to maintain it.

Keeping the air conditioning filter in good condition is essential to ensure health and comfort inside the vehicle, especially during winter when drivers keep the windows closed, use heated air, and activate air recirculation. This practice, common on cold days, reduces natural ventilation and favors the accumulation of pollutants, harmful particles, and microorganisms inside the car.

According to experts, the lack of proper maintenance of the system can turn the cabin into a breeding ground for fungi, bacteria, and allergens. Therefore, paying attention to the air conditioning filter becomes even more important at this time of year, both to preserve air quality and to avoid health problems and failures in the ventilation system.

Care with the air conditioning filter

During winter, the habit of keeping the car closed for long periods compromises the renewal of indoor air. As a result, pollutant particles tend to concentrate in the cabin.

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Health impacts: risks go beyond simple discomfort

Neglecting the air conditioning filter can cause a series of health problems, especially respiratory and dermatological issues.

According to pulmonologist Dr. Ricardo Henrique de Oliveira Braga Teixeira, poor air quality can worsen existing diseases and trigger new clinical conditions.

“Dirty filters allow the presence of allergens and particles that can trigger asthma attacks and allergic rhinitis. They can also worsen bronchitis in patients with chronic obstructive pulmonary disease and facilitate sinusitis cases,” he states.

Moreover, the effects are not limited to the respiratory system.

“Particles and pollutants clog pores, worsening cases of acne, chronic eczema, and skin irritations, potentially causing redness, itching, and swelling,” adds the specialist.

The air conditioning filter is essential in winter to prevent respiratory diseases, improve indoor air quality, and ensure comfort. Learn when to change it and how to maintain it. Image generated by AI.

Another important alert involves the presence of dangerous microorganisms.

“Immunocompromised patients are more susceptible to bacteria and fungi present in the air conditioning system. One of the most concerning is Legionella, associated with poorly sanitized systems,” he highlights.

Air quality also affects the driver’s attention

In addition to physical impacts, poor air quality inside the car can directly impair concentration.

According to Dr. Ricardo Teixeira, closed and poorly ventilated environments favor the accumulation of carbon dioxide.
“This can cause drowsiness, mental fatigue, and even loss of attention, especially on long trips or in heavy traffic,” he explains.

Therefore, keeping the air conditioning filter in good condition is also a safety measure on the road.

Types of air conditioning filters and which to choose

There are different models of air conditioning filters, and the correct choice can make all the difference in indoor air quality.

According to Diogo Rocha, technical coordinator at Wega, there are two main options on the market:

Filter type	Characteristics
Conventional	Retains solid particles
Activated carbon	Filters particles, odors, and gases

He recommends a specific option for winter.

“The activated carbon filter is more suitable, as it provides superior air quality and helps keep the cabin dry, making it difficult for bacteria to proliferate,” he explains.

Signs that the air conditioning filter needs to be replaced

Some signs indicate that the air conditioning filter is already saturated and needs to be replaced.

The main ones are:

Reduction in airflow
Bad smell inside the vehicle
Delay in defogging the windows
Increase in allergies
Noises in the ventilation system

According to Luiz Gustavo Vieira, ignoring these signs can lead to problems.

“When the filter is saturated, the ventilation system motor has to work harder, which increases energy consumption and reduces the efficiency of the air conditioning,” he warns.

Ideal interval for changing the air conditioning filter

The standard recommendation is to change the air conditioning filter every six months or between 10,000 and 15,000 kilometers.

However, this interval may be shorter under certain conditions.

“Humidity accelerates filter saturation. In colder and more humid regions, it is ideal to replace the component every three months or at least twice a year,” advises Diogo Rocha.

Even rarely used vehicles need this attention, as dirt accumulation occurs over time.

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Does changing the filter solve everything? Understand what else needs to be done

Although fundamental, changing the air conditioning filter does not solve all problems related to air quality.

Luiz Gustavo Vieira emphasizes the importance of complete maintenance.

“The replacement of the filter should be accompanied by cleaning the ducts, sanitizing the system, and internal vacuuming. This combination ensures a healthier and more comfortable environment,” he states.

Additionally, opening the windows occasionally helps to renew the indoor air and reduce the concentration of pollutants.

The air conditioning filter is a component often neglected but plays an essential role in well-being inside the vehicle.

Especially in winter, when the environment becomes more closed, taking care of this item is a simple measure that can prevent diseases, improve comfort, and even increase safety while driving.

With information from AutoEsporte

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Experts warn: a dirty car air conditioning filter in winter can accumulate fungi and bacteria, causing allergies, fatigue, and even loss of attention while driving.

The air conditioning filter is essential in winter to prevent respiratory diseases, improve indoor air quality, and ensure comfort. Learn when to change it and how to maintain it.

Care with the air conditioning filter

Health impacts: risks go beyond simple discomfort

Air quality also affects the driver’s attention

Types of air conditioning filters and which to choose

Signs that the air conditioning filter needs to be replaced

Ideal interval for changing the air conditioning filter

Does changing the filter solve everything? Understand what else needs to be done

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Experts warn: a dirty car air conditioning filter in winter can accumulate fungi and bacteria, causing allergies, fatigue, and even loss of attention while driving.

The air conditioning filter is essential in winter to prevent respiratory diseases, improve indoor air quality, and ensure comfort. Learn when to change it and how to maintain it.

Care with the air conditioning filter

Health impacts: risks go beyond simple discomfort

Air quality also affects the driver’s attention

Types of air conditioning filters and which to choose

Signs that the air conditioning filter needs to be replaced

Ideal interval for changing the air conditioning filter

Does changing the filter solve everything? Understand what else needs to be done

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Brazil will harvest a record crop of up to 357 million tons of grains, but it does not have the capacity to store a large part of it. The storage deficit has reached the highest level in history and is equivalent to almost the entire production of Argentina.

Four times faster than the Concorde, capable of taking passengers from New York to London in less than an hour at Mach 5.5, and with an engine that switches from turbojet to ramjet mid-flight at Mach 3.5, the Hermeus Quarterhorse went from paper to its first flight in just 19 months.

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She started by collecting oyster shells from restaurants and today she has already accumulated more than 10 tons to restore reefs, recover coastal habitats, and demonstrate how a common waste can become a tool for ocean conservation.

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