Distinguishing P1, P2, P3, and P4 laboratories according to biosafety standards

In the context of rapid growth in industries such as pharmaceuticals, food, healthcare, and biotechnology, biological laboratories play a pivotal role in research, production, and quality testing. These facilities come into direct contact with microorganisms, viruses, and infectious agents, which makes biosafety requirements a mandatory factor that determines both operational effectiveness and safety.

To ensure an appropriate level of protection for each type of biological agent, international health organizations such as the WHO and CDC have established a classification system that divides laboratories into four biosafety levels, from P1 to P4 (corresponding to BSL-1 to BSL-4). Each level specifies requirements for architecture, equipment, procedures, and the degree of biological risk control.

So, what are the differences between P1, P2, P3, and P4 laboratories? Which type of research is each level suitable for? And what should businesses keep in mind when building a compliant laboratory? This article by VCR will help you clearly understand the classification criteria, compare in detail the technical features, equipment, and protection levels, and provide practical application suggestions for various industries. Based on this information, you will gain an overview of how to distinguish P1, P2, P3, and P4 laboratories according to biosafety standards, ensuring research activities are carried out safely and effectively.

Overview of Biosafety Standards (BSL)

What is BSL?

BSL (Biosafety Levels) is a classification system for biological laboratories based on the level of risk when working with microorganisms, viruses, bacteria, and other agents that may cause disease in humans, animals, or the environment.

Each biosafety level - from BSL-1 to BSL-4 (corresponding to P1 to P4) - specifies detailed requirements regarding:

• Laboratory architectural and engineering design
• Operational procedures and safety controls
• Type of personal protective equipment (PPE) and ventilation systems
• Level of personnel training and supervision

What Is Biological Safety Level?

Who establishes BSL standards?

The BSL standards are developed and promoted by leading international organizations such as:

• CDC (Centers for Disease Control and Prevention, USA)
• NIH (National Institutes of Health, USA)
• WHO (World Health Organization)

In Vietnam, these standards are also referenced and adapted for the construction of microbiology, pharmaceutical, and medical testing laboratories, especially those required to comply with GMP, ISO 17025, or ISO 15189.

Criteria for classifying laboratories by BSL

Biosafety levels are determined based on four main criteria:

• Type of microorganism studied: Harmless (P1), mildly pathogenic (P2), dangerous pathogens (P3), or extremely hazardous agents with no known treatment (P4).
• Risk to humans: Considering disease-causing potential, mortality rates, and transmissibility.
• Mode of transmission: Through contact, bloodborne routes, droplets, or aerosols.
• Level of protection required: From basic PPE to full-body protective suits, air isolation systems, and negative-pressure containment.

Correctly identifying the appropriate BSL level is a crucial foundation for designing, building, and operating safe laboratories - especially in the context of emerging biological threats worldwide.

Distinguishing Laboratory Levels P1-P4

1. P1 Laboratory (BSL-1) - The Basic Level of Biosafety

Research subjects

P1 (BSL-1) laboratories are the simplest and lowest-risk facilities, used for studying microorganisms that do not cause disease in humans under normal conditions. These include low-level bacteria, fungi, or viruses commonly found in nature and harmless to healthy individuals.

Example: Escherichia coli strain K-12 (a non-pathogenic bacterium widely used in teaching and molecular biology research).

Level of protection: Minimal

P1 labs require only basic safety measures, with negligible risk. Nevertheless, compliance with hygiene protocols, proper disposal of biological waste, and staff safety training remain essential.

Special protective equipment such as N95 masks or biosafety cabinets is not required, but personnel must wear lab coats, gloves, safety glasses, and wash their hands after handling materials.

Basic design requirements

• Enclosed room with doors that can be closed
• Handwashing sink with running water
• Slip-resistant, easy-to-clean flooring
• Design must ensure no eating, drinking, smoking, or food storage in the work area

No need for negative pressure ventilation or HEPA filtration systems.

Required equipment

• Standard laboratory workbenches
• Chemical storage cabinets
• Handwashing sink near the entrance
• Containers for biological waste
• Basic safety signage

No requirement for biosafety cabinets (BSC), interlock systems, or pass boxes.

Practical applications

• P1 laboratories are commonly used in:
• Universities and colleges: training students in biomedical sciences and microbiology
• Educational labs at high schools
• Basic biological research facilities not involving pathogenic agents
• Agricultural and plant biotechnology research labs

Biosafety Levels 1 & 2: What’s the Difference?

P2 Laboratory (BSL-2) - The Most Common Biosafety Standard in Industry and Testing

Research subjects

P2 (BSL-2) laboratories are designed to handle microorganisms that can cause mild to moderate illness in humans but are generally not life-threatening if timely medical treatment is available. These agents include certain bacteria, viruses, and parasites transmitted through direct or indirect contact.

Typical examples: Salmonella spp., Staphylococcus aureus, Hepatitis A and B, common influenza viruses.

Transmission risks

• Indirect contact: via hands, work surfaces, contaminated instruments
• Through sharps: needles, broken glassware
• No significant airborne transmission risk under normal working conditions

Therefore, P2 requires stricter biosafety controls than P1.

Additional equipment and design requirements

P2 laboratories must include the following design features and equipment:

• Biosafety Cabinet (BSC) Class I or II
  • HEPA-filtered supply and exhaust air
  • Prevents aerosol release during microbial handling
• Door locks or access control systems to restrict unauthorized entry
• Biosafety hazard warning signs posted at entrances
• Separate storage for samples, chemicals, and instruments
• Biological waste treatment systems: sterilization, autoclave

Mandatory personal protective equipment (PPE)

• Laboratory coats
• Specialized gloves, changed regularly
• Splash shields or safety goggles
• Medical masks or fine particle respirators for certain procedures

Infrastructure requirements

• Floors and walls that are easy to clean and disinfect
• Dedicated handwashing stations
• Ventilation systems exhausting air outward, avoiding recirculation
• Recommended use of surveillance cameras and entry/exit log systems

Practical applications

P2 laboratories are the most widely adopted standard in industry and healthcare, with broad applications such as:

• Pharmaceuticals: microbiological testing, bacterial count evaluation
• Food industry: detecting foodborne pathogens like Listeria and E. coli
• Cosmetics: testing for microbes that cause spoilage or skin irritation
• Healthcare, clinics, research institutes: serological testing, diagnostics of mild infectious diseases
• Molecular biology and academia: research on genes, plasmids, and genetically modified bacteria

P3 Laboratory (BSL-3) - Biosafety Standard for Dangerous Infectious Agents

Agents handled in P3 laboratories

P3 (BSL-3) laboratories are designed to handle microorganisms capable of causing severe disease in humans, with high mortality risks, and easily transmitted through aerosols or airborne particles.

This level is applied in the research and handling of agents such as:

• Mycobacterium tuberculosis (tuberculosis)
• Influenza viruses H5N1, H7N9
• SARS-CoV-1, SARS-CoV-2 (in the early stages before vaccines were available)
• Pathogens causing plague, Q fever, or other zoonotic/re-emerging diseases

Level of protection: High - strict requirements

P3 laboratories are capable of isolating biological agents from the external environment, preventing leakage and aerosol dissemination.

Protective measures include:

• Continuous negative pressure: ensures air flows inward only, not outward
• HEPA filtration: removes 99.97% of particles ≥0.3 microns
• Airlock entry systems with interlocking doors
• Exhaust air must not be recirculated; it must be fully filtered and decontaminated before release

Technical and infrastructure design requirements

• Independent HVAC systems: separate air conditioning for each laboratory area
• Walls, floors, and ceilings must be non-porous and easy to disinfect
• Airtight doors with sealed pressure gaskets
• Pressure differential alarms and monitoring sensors
• FFUs (Fan Filter Units) providing localized clean air with HEPA filtration

Class II or Class III Biosafety Cabinets (BSC) are mandatory for all microbial handling

Biological Cleanroom: Definition, Design, Application

Mandatory personal protective equipment (PPE)

• Full-body protective suits (when required)
• Double gloves
• Face shields or safety goggles
• N95 respirators or powered air-purifying respirators (PAPR)

Practical applications

P3 laboratories are typically used for:

• Vaccine research and production (e.g., seasonal influenza, tuberculosis, recombinant viruses)
• Pharmaceutical microbiology laboratories: testing of high-risk bacteria
• National or specialized biomedical research institutes
• Research centers for dangerous infectious and zoonotic diseases

Special notes

The design and operation of P3 laboratories must strictly comply with WHO and CDC guidelines and usually require validation and approval by national health authorities before use.

All laboratory activities must be logged, and staff must undergo advanced training in molecular biology, biosafety, and emergency response.

P4 Laboratory (BSL-4) - The Highest Level of Biosafety

Extremely hazardous agents - no available treatment

P4 (BSL-4) laboratories represent the highest level of biosafety, designed to study agents that are:

• Extremely dangerous
• Rapidly transmissible through air, bodily fluids, or direct contact
• Without vaccines or effective treatment methods

Examples of agents handled in P4 laboratories include:

• Ebola virus
• Marburg virus
• Newly emerging dangerous viral variants with pandemic potential

These biological agents can cause very high mortality rates, spread quickly, and pose severe community risks if accidental release occurs.

Maximum protection - absolute safety

P4 laboratories are built as “biological fortresses” with multiple containment layers to prevent any leakage:

• Dual HEPA filtration: both supply and exhaust air pass through two layers of HEPA filters to eliminate all infectious particles
• Full-body positive-pressure protective suits:
  • Equipped with independent air supply
  • Positive internal pressure prevents contaminated air from entering
• Multi-stage airlock chambers: strictly control personnel entry and exit, combined with decontamination showers
• Fully independent HVAC systems: not shared with any other areas
• Airtight walls, ceilings, and concrete floors with no cracks or leakage risks

Entire laboratory monitored 24/7 with CCTV, gas sensors, pressure monitors, and biometric access control

Special applications

Due to the extremely high level of risk, P4 laboratories are built only at select national virology institutes or major disease control centers.

Typical applications include:

• Research and development of vaccines for untreatable viruses
• Testing biological responses and developing new treatment protocols
• Handling mutated viral strains with global pandemic potential

In Vietnam, facilities meeting international standards for P4 laboratory design and operation are still extremely rare.

Applications of Each Laboratory Level by Industry

Each industry has specific requirements for biosafety levels when operating laboratories. Choosing the appropriate level not only ensures legal compliance but also directly impacts testing effectiveness, production quality, and personnel safety.

Below are suggested applications of each laboratory level (P1-P4) by sector:

Pharmaceutical industry

In pharmaceuticals, especially in the production of injectables, vaccines, and antibiotics, laboratory requirements go beyond cleanliness to include biosafety compliance under GMP.

• Microbiological testing and QC laboratories: minimum P2, equipped with Biosafety Cabinets (BSC) and biological waste treatment systems.
• Weighing rooms for raw materials, molecular biology research labs: if handling infectious agents or clinical samples, P3 is recommended.
• Vaccine or biopharmaceutical research: requires P3 or higher, particularly when working with recombinant or variant viruses without available treatments.

Food industry

Food manufacturers must control harmful microorganisms, particularly bacterial strains such as Salmonella, Listeria, and E. coli.

• Routine testing laboratories: P2 is sufficient for handling food samples at risk of contamination.
• Fermentation and probiotic R&D labs: if working with strong or novel microbial strains, upgrading to P3 may be considered - especially for large-scale R&D projects or international collaborations.

Cosmetics industry

For cosmetics, especially skincare products, serums, and handmade items, microbiological testing is essential to ensure consumer safety.

• Microbiological testing labs: typically meet P2 standards, using Class I or II BSCs for sample handling.
• Biological or naturally fermented cosmetics: should ideally be processed in a closed sterile area. While P3 is not mandatory, it is advisable to invest in designs approaching P3 standards (ISO 7-8 cleanroom, mild pressure differentials).

Healthcare and virology research

This sector demands the highest biosafety standards, particularly in:

• National virology institutes, tropical disease hospitals
• Frontline epidemiological testing laboratories
• Agents such as tuberculosis, influenza H5N1, SARS, and COVID-19 require P3 laboratories with negative pressure, HEPA filtration, and closed operational procedures.
• For Ebola, Marburg, or other untreatable viruses, P4 laboratories are mandatory.

Conclusion

Selecting the correct laboratory biosafety level helps organizations comply with regulations, ensure biological safety, and strengthen international credibility.

Safety tips in biology laboratories

Related Standards & Recommendations for Laboratory Construction

To design and operate a laboratory that meets biosafety requirements, organizations should not only follow the BSL (Biosafety Levels) system but also comply with a number of international and regional standards. Below are some widely applied frameworks:

Relevant technical standards

In addition, other sector-specific standards apply:

• Pharmaceuticals: GMP (Good Manufacturing Practice), GLP (Good Laboratory Practice)
• Food industry: HACCP, ISO 22000
• Cosmetics: ISO 22716

Recommendations for laboratory construction by level

Laboratory construction cannot be “assembled arbitrarily”; it requires professional planning and consultation:

• Design layouts according to clean-dirty flow
• Divide areas by pressure differentials and ISO cleanroom classes 5-8
• Ensure segregation and risk control according to each BSL level

VCR recommends starting with a clear plan:

1. Identify the biological agents to be handled → select the appropriate P-level
2. Define functional zones: airlocks, working rooms, sample storage, corridors
3. Equip the facility with devices suitable for each biosafety level

Suggested Equipment by Level (P1 → P4)

You can find more details on specialized product websites such as:

• ffu.com.vn
• passbox.vn
• khoaliendong.com
• cuaphongsachvcr.com

Conclusion

Understanding and distinguishing between P1, P2, P3, and P4 laboratories not only helps organizations comply with biosafety standards but also ensures efficiency in research, production, and testing. Each level offers a different degree of protection, from basic (P1) to maximum (P4), corresponding to the risks posed by the biological agents being handled.

Choosing the wrong laboratory level can result in regulatory violations, wasted investment, or serious risks to staff and the environment. Therefore, laboratory consulting, design, and construction should be carried out by professionals with expertise in international standards and industry-specific requirements.

If you are planning to build or upgrade a P1-P4 compliant laboratory, contact VCR’s team of experts today for free consultation on design solutions, equipment selection, and safe operating procedures.

PN