Construction Health and Safety Technician (CHST) Practice Test

What type of radiation can be effectively filtered out by an air purifying respirator with a high efficiency particulate filter?

1. Beta

2. Gamma

3. Alpha

4. X-ray

The correct answer is: Alpha

Air purifying respirators with high-efficiency particulate filters (HEPA filters) are designed to capture airborne particles, including dust, pollen, mold spores, and certain biological agents. When it comes to types of radiation, alpha particles are relatively large and positively charged particles that can be effectively blocked by materials like paper or skin, and thus by HEPA filters as they can capture the larger particulate matter. In contrast, gamma rays and x-rays are forms of electromagnetic radiation that have high energy and can penetrate materials more deeply due to their small size and lack of charge. These types of radiation cannot be effectively filtered out by air purifying respirators because HEPA filters are not designed to attenuate non-particulate radiation. Beta radiation, while having more mass than alpha particles, can also penetrate materials more effectively than alpha particles, but still, a proper shielding or absorbing material rather than filtration is needed to address it. Thus, the reason alpha radiation is the correct answer is that it is effectively filtered out by HEPA filters, while beta, gamma, and x-ray radiation require different protective measures.