Final answer:
Air filters are designed to remove contaminants from the air, but they do not remove almost all contaminants.
Step-by-step explanation:
Air filters are designed to remove contaminants from the air, but they do not remove almost all contaminants. They are effective at removing larger particles such as dust, pollen, and pet dander. However, smaller contaminants like gases and odors may not be filtered out completely. Additionally, the efficiency of air filters can vary depending on their design and quality.