CDC Reviews Air Quality in BSL-4 Lab Protective Suits

The Centers for Disease Control and Prevention (CDC) conducted a safety review in February 2017 regarding the air quality of breathing hoses used in its Biosafety Level 4 (BSL-4) laboratories. The review focused on whether laboratory scientists were exposed to chemical compounds from the hoses attached to their protective suits.

The agency suspended laboratory work involving these air hoses on February 16, 2017. This action followed a notification the CDC received on February 13, 2017, from the company that now owns the manufacturer of the hoses.

The manufacturer informed the agency that the current stock of hoses used in the BSL-4 labs was not approved for use as breathing air. This prompted the CDC to test the air passing through the hoses to determine if any chemical compounds posed a health risk to workers.

Laboratory Safety and Containment

BSL-4 laboratories are designed for maximum containment to handle the most dangerous pathogens in the world. These facilities manage biological agents that pose the highest risk to human health, particularly those for which no vaccines or treatments are currently available.

To protect researchers, these labs utilize an integrated system of protection. This includes facility design, air handling systems, and rigorous decontamination procedures, alongside advanced personal protective equipment (PPE).

The core of BSL-4 PPE is the full-body positive pressure suit. These suits act as an impenetrable barrier between the scientist and the pathogens. Because these suits are sealed, researchers rely on air hoses to provide a continuous supply of breathable air.

The air supplied through these hoses is filtered for pathogens using High Efficiency Particulate Air (HEPA) filters. During the 2017 review, the CDC stated that it knew of no exposure to hazardous pathogens or contaminated air within the labs.

Review Findings and Resolution

The CDC utilized an external accredited laboratory to perform independent testing on the air supplied by the breathing hoses. This testing was designed to verify if the air quality met the necessary safety thresholds for personnel.

On February 27, 2017, the CDC announced that the independent testing was complete. The results determined that the air supplied by the hoses in use met the Occupational Safety and Health Administration (OSHA) standard for breathable air.

Following the confirmation that the air quality was acceptable, work in the BSL-4 laboratories resumed on February 27, 2017. The safety of the breathing hoses was further confirmed in reports dated March 1, 2017.

The agency indicated that current and former laboratory workers would receive information regarding the review process to ensure transparency regarding workplace exposures.

The Role of BSL-4 PPE

The equipment used in BSL-4 environments represents the most comprehensive protective gear in the field of biosafety. Every component is meticulously tested to prevent the release of potentially catastrophic biological agents into the environment and to safeguard the health of the staff.

In addition to the positive pressure suits and breathing hoses, BSL-4 PPE typically includes multiple layers of protective gloves. This layered approach ensures that if one barrier is compromised, additional protections remain in place.

The 2017 incident highlighted the critical nature of the supply chain for biosafety equipment. Even when pathogens are successfully filtered out by HEPA systems, the materials used in the delivery systems, such as the hoses themselves, must meet strict regulatory approvals for breathable air to avoid chemical contamination.