What happens to filtration efficiency as an air filter becomes clogged?

As an air filter becomes clogged, the filtration efficiency decreases due to reduced airflow and increased resistance. Initially, a clean air filter can trap particles effectively, providing a high level of filtration. However, as dust and other particulate matter accumulate on the filter media, it becomes more difficult for air to pass through.

This blockage not only hinders the flow of air but also can cause smaller particles to bypass the filter media altogether. The phenomenon is known as the "bypass" effect, where air finds alternative paths, reducing the overall effectiveness of capturing contaminants. Additionally, as air is forced through the limited spaces that remain open, the filter loses its ability to trap particles efficiently.

While there may be scenarios where a new filter performs better than an older one as it might capture larger particles initially, the continued accumulation of dirt and debris will ultimately compromise the filter's performance and reduce its overall efficiency. This understanding is crucial for maintaining good indoor air quality, ensuring that filters are changed or cleaned regularly before they reach a clogged state.