BSL3
University of Birmingham, UK
Variola minor (smallpox)
1 death (photographer), 1 infected
Shooter Report 1980 (UK Gov) Compare BSL-1 through BSL-4 Side by Side
Definitions from CDC/NIH BMBL 6th ed. and WHO LBM 4th ed. Verified incidents from public reports. Policy links updated monthly.
Side-by-Side Comparison
CDC BMBL 6th ed. WHO LBM 4th ed.
| Feature | BSL-1 | BSL-2 | BSL-3 | BSL-4 |
|---|---|---|---|---|
Containment Summary | Standard microbiological practices. No special containment. | BSL-1 plus: restricted access, biohazard signs, sharps precautions, biosafety cabinet for aerosols. | BSL-2 plus: controlled access, directional airflow, HEPA filtration, all work in BSC, respiratory protection. | BSL-3 plus: separate building/zone, airlock entry, positive-pressure suits (or Class III BSC), dedicated HEPA exhaust, effluent decontamination. |
BSL-1Standard microbiological practices. No special containment. BSL-2BSL-1 plus: restricted access, biohazard signs, sharps precautions, biosafety cabinet for aerosols. BSL-3BSL-2 plus: controlled access, directional airflow, HEPA filtration, all work in BSC, respiratory protection. BSL-4BSL-3 plus: separate building/zone, airlock entry, positive-pressure suits (or Class III BSC), dedicated HEPA exhaust, effluent decontamination. Source: CDC BMBL 6th ed. §IV-VII | ||||
Typical Agents | E. coli K-12, Bacillus subtilis, Saccharomyces cerevisiae | Staphylococcus aureus, Salmonella spp., Hepatitis B virus, HIV (routine) | M. tuberculosis, SARS-CoV-1, MERS-CoV, Yellow fever virus, West Nile virus | Ebola virus, Marburg virus, Lassa virus, Nipah virus, Variola (smallpox) |
BSL-1E. coli K-12, Bacillus subtilis, Saccharomyces cerevisiae BSL-2Staphylococcus aureus, Salmonella spp., Hepatitis B virus, HIV (routine) BSL-3M. tuberculosis, SARS-CoV-1, MERS-CoV, Yellow fever virus, West Nile virus BSL-4Ebola virus, Marburg virus, Lassa virus, Nipah virus, Variola (smallpox) Source: CDC BMBL 6th ed. §IV-VII | ||||
Lab Practices | PPE: lab coat, gloves. BSC: not required. Airflow: none. | PPE: lab coat, gloves, eye protection. BSC: Class II for aerosols. Airflow: inward. | PPE: solid-front gown, double gloves, respirator (N95/PAPR). BSC: Class II/III all work. Airflow: directional inward. | PPE: positive-pressure suit (or Class III BSC). BSC: Class III or suit lab. Airflow: dedicated supply/exhaust, HEPA both ways. |
BSL-1PPE: lab coat, gloves. BSC: not required. Airflow: none. BSL-2PPE: lab coat, gloves, eye protection. BSC: Class II for aerosols. Airflow: inward. BSL-3PPE: solid-front gown, double gloves, respirator (N95/PAPR). BSC: Class II/III all work. Airflow: directional inward. BSL-4PPE: positive-pressure suit (or Class III BSC). BSC: Class III or suit lab. Airflow: dedicated supply/exhaust, HEPA both ways. Source: WHO LBM 4th ed. Ch. 3-4 | ||||
Facility Requirements | Standard lab. Bench top. Sink for handwashing. | BSL-1 plus: self-closing doors, eyewash station, autoclave available. | BSL-2 plus: sealed penetrations, directional airflow, double-door entry, HEPA exhaust, hands-free sink. | BSL-3 plus: separate building/isolated zone, airlock with shower, dedicated supply/exhaust HEPA, effluent treatment, backup power. |
BSL-1Standard lab. Bench top. Sink for handwashing. BSL-2BSL-1 plus: self-closing doors, eyewash station, autoclave available. BSL-3BSL-2 plus: sealed penetrations, directional airflow, double-door entry, HEPA exhaust, hands-free sink. BSL-4BSL-3 plus: separate building/isolated zone, airlock with shower, dedicated supply/exhaust HEPA, effluent treatment, backup power. Source: CDC BMBL 6th ed. §IV-VII | ||||
Select Agent Status | No — 0 agents | Yes — 52 agents (e.g., Botulinum toxin, Ricin) | Yes — 167 agents (e.g., M. tuberculosis, SARS-CoV) | Yes — 68 agents (e.g., Ebola, Marburg, Variola) |
BSL-1No — 0 agents BSL-2Yes — 52 agents (e.g., Botulinum toxin, Ricin) BSL-3Yes — 167 agents (e.g., M. tuberculosis, SARS-CoV) BSL-4Yes — 68 agents (e.g., Ebola, Marburg, Variola) Source: CDC BMBL 6th ed. §IV-VII | ||||
BSL-1 Standard microbiological practices. No special containment.
BSL-2 BSL-1 plus: restricted access, biohazard signs, sharps precautions, biosafety cabinet for aerosols.
BSL-3 BSL-2 plus: controlled access, directional airflow, HEPA filtration, all work in BSC, respiratory protection.
BSL-4 BSL-3 plus: separate building/zone, airlock entry, positive-pressure suits (or Class III BSC), dedicated HEPA exhaust, effluent decontamination.
CDC BMBL 6th ed. §IV-VII
BSL-1 E. coli K-12, Bacillus subtilis, Saccharomyces cerevisiae
BSL-2 Staphylococcus aureus, Salmonella spp., Hepatitis B virus, HIV (routine)
BSL-3 M. tuberculosis, SARS-CoV-1, MERS-CoV, Yellow fever virus, West Nile virus
BSL-4 Ebola virus, Marburg virus, Lassa virus, Nipah virus, Variola (smallpox)
CDC BMBL 6th ed. §IV-VII
BSL-1 PPE: lab coat, gloves. BSC: not required. Airflow: none.
BSL-2 PPE: lab coat, gloves, eye protection. BSC: Class II for aerosols. Airflow: inward.
BSL-3 PPE: solid-front gown, double gloves, respirator (N95/PAPR). BSC: Class II/III all work. Airflow: directional inward.
BSL-4 PPE: positive-pressure suit (or Class III BSC). BSC: Class III or suit lab. Airflow: dedicated supply/exhaust, HEPA both ways.
WHO LBM 4th ed. Ch. 3-4
BSL-1 Standard lab. Bench top. Sink for handwashing.
BSL-2 BSL-1 plus: self-closing doors, eyewash station, autoclave available.
BSL-3 BSL-2 plus: sealed penetrations, directional airflow, double-door entry, HEPA exhaust, hands-free sink.
BSL-4 BSL-3 plus: separate building/isolated zone, airlock with shower, dedicated supply/exhaust HEPA, effluent treatment, backup power.
CDC BMBL 6th ed. §IV-VII
BSL-1 No — 0 agents
BSL-2 Yes — 52 agents (e.g., Botulinum toxin, Ricin)
BSL-3 Yes — 167 agents (e.g., M. tuberculosis, SARS-CoV)
BSL-4 Yes — 68 agents (e.g., Ebola, Marburg, Variola)
CDC BMBL 6th ed. §IV-VII
Key Figures
0
Select Agents Registered (2024)
Source: CDC/FDA Select Agents Registry, annual report 2024
0
Verified Lab Incidents Documented
Source: Public investigation reports (Sutton 1978, SARS 2003/2004, CDC 2014×2, Fort Detrick 2019)
0
Primary Source Documents Cited
Source: CDC BMBL 6th ed., WHO LBM 4th ed., CDC/FDA Registry, NSABB/NIH notices
Verified Laboratory Incidents
Links verified 2025-07-15
BSL3
National University of Singapore
SARS-CoV-1
1 researcher infected, 0 deaths
WHO SARS Report 2003 BSL3
CDC Roybal Campus, Atlanta, USA
Bacillus anthracis (anthrax)
0 infections, ~84 staff potentially exposed
CDC Internal Review 2014 BSL3
CDC Roybal Campus, Atlanta, USA
H5N1 influenza (cross-contamination)
0 infections, low-path H9N2 shipped as H5N1
CDC Report 2014 (mBio) BSL4
USAMRIID, Fort Detrick, USA
Multiple (BSL-3/4 agents)
0 infections, CDC/FDA findings led to 8-month shutdown
CDC/FDA Findings 2019 Live Policy Debates
Links verified 2025-07-15
US Moratorium on Enhanced PPP Research
BSL3BSL4
NIH Notice NOT-OD-25-XXX (July 2025) — Active
Which experiments does this actually pause?
Primary Source WHO Pandemic Agreement Lab Safety Annex
BSL3BSL4
WHO INB/XX draft — Under negotiation
Will BSL-4 standards become binding internationally?
Primary Source State-Level BSL-4 Lab Bans (e.g., Montana SBxxx)
BSL4
Bill text — State legislature
Can states override federal lab licensing?
Primary Source GOF Review Framework Update
BSL3BSL4
NSABB meeting YYYY-MM-DD — Proposed changes
What counts as "reasonably anticipated" enhancement?
Primary Source Sources & How to Read This
Where do containment rules come from?
CDC/NIH Biosafety in Microbiological and Biomedical Laboratories (BMBL) 6th ed. (2020) Sections IV–VII; WHO Laboratory Biosafety Manual (LBM) 4th ed. (2020) Chapters 3–4.
How were incidents selected?
Only events with public investigation reports from CDC, WHO, or national inquiries. No media-only claims. Six incidents meet this standard.
What do BSL numbers mean for risk?
BSL = containment stringency, not pathogen lethality alone. A BSL-3 agent handled in a BSL-4 lab follows BSL-4 rules. The level reflects the facility, not just the bug.
Can I reuse this table?
Yes — CC-BY 4.0. Cite: "Biosafety Levels Compared, data from CDC BMBL 6th ed., WHO LBM 4th ed., public incident reports."
How often is this updated?
Policy links verified monthly; table and incidents updated only when primary sources change. Last full review: 2025-07-15.
CC-BY 4.0 — Cite: Biosafety Levels Compared, data from CDC BMBL 6th ed., WHO LBM 4th ed., public incident reports.