If air filters aren't cleaned for a long time, will the dust accumulation on their surface breed bacteria and affect indoor air quality?

Many people install air filters at home and forget about them, going a year or two without cleaning. Some think it's just a little dust accumulation that won't affect their use; others worry that excessive dust accumulation could lead to bacterial growth, affecting indoor air quality and even our health.

Causes

Air filters are designed to block impurities such as dust and lint from the air. Over time, these impurities adhere to the filter fibers, forming a thicker and denser buildup. The filter itself is a mesh structure that can be somewhat humid. Combined with the typical indoor temperature of 20-25°C, this creates a perfect breeding ground for bacteria. For example, dust can contain dander and pollen, which are "food" for bacteria. With food, humidity, and warmth in the filter, bacteria can multiply, growing from a few to tens of thousands. Furthermore, the air filter is constantly "working." The fan drives air through the filter, and the bacteria that grow there are carried into the room by the airflow. The intended purpose is to purify the air, but it actually becomes a "bacteria spreader," which is completely counterproductive.

Affects Indoor Air Quality and Causes Respiratory Problems

Air filters that haven't been cleaned for a long time can harbor bacteria that spread throughout the room with the airflow. For example, for elderly people, children, or those with rhinitis or asthma, breathing in this bacteria-laden air can easily irritate their respiratory tracts, causing sneezing, runny noses, coughing, and even, in severe cases, bronchitis. Besides bacteria, excessive dust accumulation can also breed mites. Their excrement and dead bodies are allergens, causing itching and rashes in those with allergies. These are all chain reactions to not cleaning the air filter.

Affects Filtration Effectiveness

Even if there aren't obvious bacterial issues at the moment, a thick layer of dust from an air filter that hasn't been cleaned for a long time can clog the filter pores, making it difficult for air to pass through. During this period, both the air conditioner and purifier will struggle to blow air, resulting in reduced air volume and reduced filtration efficiency, which in turn increases dust in the air. Furthermore, prolonged overload of the fan can cause noise, increase power consumption, and even shorten the lifespan of the device. The thought of saving time on cleaning may result in a need for repairs, which is uneconomical.

Solution

If your air filter is washable, it's recommended to clean it every 1-2 months. Rinse with clean water or gently brush off dust with a soft brush. Let it dry before replacing it. Be careful not to use detergent or other chemicals, as these can damage the filter structure and compromise filtration effectiveness. If your air filter is non-washable, avoid washing it, as this can damage the filter layer. It's recommended to replace it every 3-6 months. If you have pets or live in a dusty environment, replacing it every 2 months is a better option. When removing and cleaning the air filter, be careful not to allow dust to escape. Avoid removing it directly in the room, as this can cause dust and bacteria to fall to the floor and be blown away by the wind. It's best to place the filter in a plastic bag before removing it. Once removed, take it directly to the balcony or bathroom for cleaning and replacement. After replacement, wipe the dust inside the unit with a damp cloth before installing a new filter to prevent secondary contamination.