Confined Space: What It Is, Risks and NR-33 Updates

Work in confined spaces is one of the activities with the highest lethality rate in industry. Unlike other occupational risks, where a mistake can cause an injury, a failure in assessing the atmosphere or in rescuing from a confined space usually results in multiple fatalities — affecting both the worker inside the environment and the one attempting to rescue them without proper preparation.

To mitigate these risks, the standard regulating this activity underwent its last update through Portaria MTP No. 1,690, published on June 15, 2022, and coming into force on October 03, 2022. Understanding the requirements of this updated version of NR-33 is critical not only to ensure legal compliance in audits, but also to ensure that release and rescue procedures actually work in operational practice.

What is a confined space according to NR-33?

Many professionals mistake "confined space" simply for small or tight places. However, NR-33 has an exact technical definition.

For any area or environment to be considered a confined space, it must simultaneously meet three requirements:

Not be designed for continuous human occupancy.
Have limited means of entry and exit.
Be an environment where a hazardous atmosphere exists or may exist.

In addition to these conditions, the standard defines that spaces not intended for human occupancy, with limited means of entry and exit, which are used for storing material with the potential to engulf or drown the worker, are also categorized as confined spaces.

Main operational risks in confined spaces

The greatest danger of a confined space is that many of its risks are invisible and odorless. The safety team and authorized workers constantly deal with lethal threats, the main ones described by the standard being:

Oxygen Deficiency or Enrichment: The indicated percentage for safe entry is 20.9%. Working in concentrations between 19.5% and 23% by volume is acceptable, provided the cause of this variation is known and controlled.
Explosive or Toxic Atmospheres: The presence of mixtures of air with flammable materials (gas, vapor, dust) or contaminants with the potential to cause immediate harm to the worker's health.
Engulfment and Drowning: An imminent risk in silos and tanks, engulfment occurs when the worker is surrounded and captured by solid particulate matter. Drowning, on the other hand, refers to the aspiration of non-body solids or liquids through submersion.

NR-33 Updates: What your company needs to know

The latest update of NR-33 brought important alignments to integrate the management of confined spaces into modern occupational risk management standards.

If your company still operates with old manuals, pay attention to the main requirements in force:

Integration with the PGR: Occupational risk management must include all prevention measures to ensure the health of workers who interact with the confined space, integrating this information into the Risk Management Program (PGR) of NR-01.
Detailed Register of Confined Spaces: The organization must prepare and maintain a register containing the identification of the space, volume, number of openings, forms of access, status (active or inactive), sketch (including planned isolations), and indication of potential hazards before release.
Digital Entry and Work Permit (PET): The standard made it official that the PET can be issued in physical or digital format. For digital issuance, the document must be permanently accessible to the observer during the activity and follow signature certification procedures in compliance with NR-01.
Exclusive Focus of the Observer (Vigia): The rules for those monitoring the activity have become stricter. The observer must remain outside the confined space, near the entrance, maintaining continuous control of the workers. The observer is strictly prohibited from performing other tasks during operations.

PET issuance and operational bottlenecks

The Entry and Work Permit (PET) is the document certifying that all safety measures have been adopted (such as hazardous energy isolation and initial atmospheric assessments).

The major problem for industries is that issuing a PET on paper forms often stalls operations. The supervisor wastes time collecting physical signatures in the field, gas detector test results must be transcribed by hand, and validating the worker's ASO (Occupational Health Certificate) and training often depends on time-consuming HR queries. In case of failure in this manual verification, the company assumes all civil and criminal risks of the operation.

Continue learning about Regulatory Standards (NRs)

Occupational safety management is interconnected and requires constant technical updates. Deepen your knowledge by accessing our other content about NRs:

NR-35: Work at Height
NR-01: Risk Management Program (PGR)
NR-06: Personal Protective Equipment (PPE) Management
NR-34: Hot Work