Associate Certified Entomologist (ACE) Practice Exam

What does the "N" category of respirator filters indicate?

1. Resistant to some oil

2. Oil proof and can be used when oil is present

3. Not resistant to oil

4. Capable of filtering aerosols

The correct answer is: Not resistant to oil

The "N" category of respirator filters specifically indicates that the filter is not resistant to oil. This classification is crucial in environments where air contaminants include both solid and liquid particulates, as oil aerosols can interfere with the filter's effectiveness. Filter ratings are divided into different categories based on their resistance to oil. The "N" filters are designed for environments where oil is not present, making them unsuitable in circumstances where oil aerosols are a concern because they can degrade the filter’s material and impair its performance over time. In contrast, there are other categories, such as "R" filters, which are resistant to oil but not oil proof, and "P" filters, which are oil proof and can be used safely where oil aerosols are present. Understanding these classifications helps ensure the correct filter is chosen for specific workplace hazards, ultimately protecting workers' health.