You should wear a lab coat any time you’re working with hazardous materials in a laboratory, whether those hazards are chemical, biological, radiological, or physical. That’s not just good practice. OSHA’s Personal Protective Equipment standard (29 CFR 1910.132) requires employers to provide and ensure the use of protective equipment, including lab coats, wherever hazards could cause injury through absorption, inhalation, or physical contact.
The Short Answer: Almost Always
If you’re doing bench work in a lab, the default should be to wear your lab coat. All four biosafety levels, from BSL-1 (the lowest risk, working with non-hazardous agents) through BSL-3 (serious or potentially lethal agents), require lab coats. The style changes as risk increases. BSL-3 facilities require solid-front disposable gowns rather than the standard open-front coat, but the principle holds at every level: your torso and arms need a barrier between you and whatever you’re handling.
Specific situations where a lab coat is non-negotiable include working with chemicals that could splash or spill, handling biological materials (cultures, blood, tissue), transferring cryogenic fluids (liquid nitrogen, dry ice mixtures), and any procedure involving radioactive materials. When working with cryogens specifically, OSHA requires long-sleeved shirts, lab coats, or aprons alongside face shields and safety gloves whenever exposure to cold liquid, boil-off gas, or cold surfaces is possible.
When You Need a Special Lab Coat
A standard cotton or cotton-polyester lab coat works for most routine chemistry and biology work, but certain hazards call for something different. If you’re working with pyrophoric reagents or large volumes of flammable chemicals, you need a flame-resistant lab coat. These must meet the National Fire Protection Association’s NFPA 2112 standard. A standard lab coat can actually make a fire worse, since cotton-polyester blends melt and adhere to skin. Flame-resistant coats are designed to self-extinguish and won’t continue burning once the ignition source is removed.
For high-risk biological work at BSL-3, the requirement shifts to a solid-front disposable gown. Unlike a regular lab coat that buttons or snaps up the front, a solid-front gown has no opening along the chest, reducing the chance that contaminated material reaches your clothing underneath.
Proper Fit Matters
A lab coat that doesn’t fit correctly isn’t doing its job. UC Berkeley’s environmental health and safety office provides a useful benchmark for sleeve length: when your arms hang at your sides, sleeves should reach above the thumb tip. When your arms are in a working position (bent at the bench), sleeves should cover your wrists and reach the edge of your gloves, leaving no gap of exposed skin. A coat that’s too short in the sleeves or too loose in the body creates openings where splashes can reach your clothes or skin.
Stained or torn lab coats should be replaced immediately. A coat with holes or heavy chemical staining is no longer a barrier. It’s a hazard.
When to Take It Off
Knowing when to remove your lab coat is just as important as knowing when to put it on. Lab coats should never be worn in public areas: offices, break rooms, lounges, hallways, or anywhere outside the lab. This prevents you from carrying chemical residues or biological contaminants into spaces where other people eat, work, or pass through. It also protects you from bringing outside contaminants back into the lab.
Before leaving your lab, remove your coat and hang it in a designated spot inside the lab or place disposable gowns in the appropriate waste container.
Putting It On and Taking It Off Safely
The order in which you put on and remove PPE isn’t arbitrary. The CDC outlines a specific sequence for routine laboratory procedures. When gearing up (donning), the lab coat goes on second, after hand hygiene but before safety glasses and gloves. Snap or button it completely.
When removing PPE (doffing), the sequence reverses based on contamination level, moving from the most contaminated items to the least:
- First: Remove gloves slowly and discard them into biohazard waste.
- Second: Unsnap the lab coat. Grasp the sleeve cuff of one arm and pull it off, then do the same for the other arm, turning it inside out as you go so the contaminated outer surface folds inward.
- Third: Remove safety glasses by grasping the temples, where contamination is least likely.
- Fourth: Wash your hands thoroughly with soap and water.
Cleaning and Laundering
OSHA prohibits home laundering of lab coats that serve as personal protective equipment. This means if your coat has been exposed to blood, infectious materials, or hazardous chemicals, it needs to go through an institutional or contracted laundry service, not your home washing machine. The reasoning is straightforward: home machines may not reach the temperatures or use the detergents needed to decontaminate properly. Institutional hot-water laundering typically runs at a minimum of 160°F (71°C) for at least 25 minutes. Low-temperature cycles rely on chlorine- or oxygen-activated bleach to achieve similar decontamination.
Research on white coats worn in healthcare settings has found that people tend to perceive their coats as clean as long as there’s no visible contamination, even after wearing them for weeks. In reality, the heaviest bacterial loads accumulate on sleeves and in pockets, with organisms like Staphylococcus aureus found frequently. Regular laundering on a set schedule, rather than waiting until the coat looks dirty, is the safer approach.
Common Situations That Don’t Require a Lab Coat
Not every moment in a lab requires one. If you’re working exclusively at a computer, reviewing data, or having a meeting in a lab office area separated from bench space, a lab coat isn’t necessary. The same applies if you’re briefly entering a lab to check equipment that poses no splash, spill, or exposure risk. However, most labs establish a blanket policy requiring coats for anyone in the active work area, regardless of what they’re personally doing at that moment. This eliminates guesswork and protects you if someone nearby has an accident. When in doubt, put it on.