Recognise lab hazards, read GHS labels and Safety Data Sheets, choose PPE, and understand the training and records that keep labs safe.

Lab Safety Fundamentals

> **Awareness level only.** This lesson explains the ideas so you recognise them. It does not qualify you to do this work. Before you handle chemicals, biological materials or lab equipment for real, you need the training your employer or institution requires, and you must work under supervision until they sign you off.

## Why it matters

**Personal protective equipment (PPE)** is the barrier between you and a splash, a spray or a broken flask. Choosing the wrong glove can let a solvent soak through in seconds, and the wrong eyewear leaves gaps for splashes. In the US, OSHA requires employers to assess workplace hazards and provide suitable PPE, and to train workers in its use (29 CFR 1910.132). Your lab's hazard assessment and SOPs tell you what to wear; this lesson explains the reasoning so you can follow them and ask good questions.

## PPE is the last line of defence

Safety professionals use the **hierarchy of controls**, from most to least effective:

1. **Elimination:** remove the hazard (skip a step that needs a toxic reagent).
2. **Substitution:** use something safer (a less toxic solvent, a dilute solution).
3. **Engineering controls:** isolate people from the hazard (fume hoods, biosafety cabinets, shields, interlocks).
4. **Administrative controls:** change how work is done (SOPs, training, signs, limiting time or quantity).
5. **PPE:** protect the individual (goggles, gloves, lab coat, respirator).

PPE comes last because it only works if it is the right type, fits, is worn correctly every time, and is not damaged. It does nothing for the person next to you.

## The basic lab dress code

Almost every lab requires, before you even walk in:

- **Long pants (or equivalent) and closed-toe, closed-heel shoes** that cover the foot. No sandals, no exposed skin between pants and shoes.
- **Long hair tied back**, no dangling jewellery or loose sleeves.
- **Lab coat**, buttoned, sleeves down.
- **Eye protection** whenever hazardous materials are in use, even if you are not handling them yourself.

## Eye and face protection

| Type | Protects against | Notes |
|---|---|---|
| Safety glasses with side shields | flying particles, minor splashes | must meet ANSI Z87.1 in the US (marked Z87) |
| Chemical splash goggles | liquid splashes from any direction | seal around the eyes; indirect vents |
| Face shield | splashes to the face | worn **over** goggles, never alone |
| Laser or UV eyewear | specific wavelengths | must match the laser's wavelength and optical density; physics and materials labs |

Regular prescription glasses are not safety glasses. Contact lenses are allowed in many labs with goggles, but follow your lab's rule.

## Gloves

No glove protects against everything. Each material resists some chemicals and fails against others. Two terms matter:

- **Breakthrough time:** how long before the chemical gets through.
- **Degradation:** whether the glove swells, cracks or dissolves.

| Glove | Good for | Weak against |
|---|---|---|
| Nitrile (disposable) | incidental contact with many aqueous solutions, oils, some solvents; biological work | many chlorinated and aromatic solvents, acetone (short breakthrough) |
| Latex | biological work, dexterity | many organic solvents; latex allergies |
| Neoprene | acids, bases, alcohols | some solvents |
| Butyl rubber | ketones, esters | hydrocarbons |
| Insulated / cryogenic | hot or very cold objects | chemicals (not a chemical glove) |

Always check the SDS section 8 and the glove manufacturer's chemical resistance chart. Thin disposable gloves are for **incidental splash** only: if contaminated, take them off, wash your hands and put on a new pair.

Remove gloves before touching door handles, phones or keyboards, so you do not spread contamination. Peel them off inside out without touching the outside with bare skin.

## Body protection

- **Cotton or polyester-cotton lab coat** for general chemical and biological work.
- **Flame-resistant (FR) lab coat** when working with flammable liquids in quantity, pyrophoric reagents or open flames. Synthetic fabrics can melt onto skin.
- **Disposable or fluid-resistant gowns** for BSL-2 and clinical work, often with cuffs tucked under gloves.
- **Chemical-resistant apron** over the coat for large volumes of corrosives.
- Lab coats stay in the lab; contaminated coats are laundered by the institution, not at home.

## Respiratory protection

Fume hoods and biosafety cabinets are the normal way to avoid breathing hazards. If a respirator is required, OSHA requires a written respiratory protection program, a medical evaluation, fit testing and training first (29 CFR 1910.134). Never borrow or improvise one.

## Worked example: choosing PPE for a procedure

Task: diluting concentrated hydrochloric acid into water in a fume hood.

- Hazards: corrosive splashes to eyes and skin, corrosive vapour.
- Engineering control: fume hood (vapour).
- Eyes: **chemical splash goggles**, plus a **face shield** for larger volumes.
- Hands: gloves rated for hydrochloric acid on the manufacturer's chart (often neoprene or thicker nitrile).
- Body: buttoned lab coat; apron for large volumes; closed shoes, long pants.
- Procedure: add acid to water, never water to acid.

## Common mistakes

- **Treating nitrile as universal.**
- **Wearing a face shield without goggles.**
- **Wearing gloves outside the lab** or touching shared surfaces with them.
- **Pushing safety glasses onto the forehead** "for a second".

## Quick recap

- PPE is the last line of defence after elimination, substitution, engineering and administrative controls.
- Match eye protection to the hazard: glasses for particles, goggles for splashes, face shield over goggles.
- Pick gloves from the SDS and resistance charts; change them when contaminated.
- Respirators need a formal program with fit testing.

Official source: OSHA Personal Protective Equipment, https://www.osha.gov/personal-protective-equipment (Checked on 2026-10-23.)


Use the hierarchy of controls and a procedure's hazards to select eye, hand, body and foot protection.

Choosing PPE

How to Dress for the Lab? And what about Personal Protective Equipment (PPE)? Video 3

Laboratory Personal Protective Equipment (PPE)

> **Awareness level only.** This lesson explains the ideas so you recognise them. It does not qualify you to do this work. Before you handle chemicals, biological materials or lab equipment for real, you need the training your employer or institution requires, and you must work under supervision until they sign you off.

## Why it matters

Fume hoods and biosafety cabinets are the most important **engineering controls** in a lab: they keep hazards away from your lungs without relying on PPE. They look similar (a box with a glass sash and airflow), but they protect against different things and are not interchangeable. Using the wrong one, or using the right one badly, can expose you and everyone in the room.

## The chemical fume hood

A **chemical fume hood** pulls room air in through the front opening, past your work, and exhausts it out of the building through ductwork and a fan on the roof.

- **Protects:** you (and the lab) from chemical vapours, gases, dusts and small splashes (the sash acts as a shield).
- **Does not protect:** your sample from contamination. Air is unfiltered room air.
- **Typical face velocity:** around 80 to 120 feet per minute (about 0.4 to 0.6 m/s) at the working sash height; your institution tests and certifies each hood, often yearly, and marks the approved sash height.

### Using a fume hood well

1. **Check that it is working** before starting: look at the airflow monitor or alarm, or a tissue strip at the sash. If it alarms or looks wrong, do not use it; report it.
2. **Work at least 6 inches (15 cm) inside the sash**, where capture is reliable.
3. **Keep the sash at or below the marked height**, and lower it when you are not reaching in. The sash protects your face.
4. **Do not clutter it.** Bottles and equipment block airflow to the rear baffle slots. Raise large equipment on blocks so air flows underneath.
5. **Do not store chemicals in the working hood.** Use ventilated storage cabinets.
6. **Move slowly.** Fast arm movements and people walking past create turbulence that pulls vapour out.
7. **Never put your head inside** the hood.

## The biological safety cabinet (BSC)

A **biosafety cabinet** uses **HEPA filters** (which trap at least 99.97% of particles at 0.3 µm) to clean the air. The most common type, **Class II**, gives three kinds of protection:

- **Personnel:** room air is drawn in at the front grille, so aerosols do not escape toward you.
- **Product:** HEPA-filtered air flows down over the work surface, protecting cultures from contamination.
- **Environment:** exhaust air passes through a HEPA filter.

| Class | Protects | Use |
|---|---|---|
| Class I | personnel, environment | rarely used now |
| Class II (A2, B1, B2) | personnel, product, environment | most BSL-2 and BSL-3 work |
| Class III | maximum: a sealed glove box | BSL-4 and the highest-risk work |

**Important:** HEPA filters trap particles, not chemical vapours. Many Class II cabinets (type A2) recirculate most of their air back into the room or cabinet, so they are **not** for volatile or toxic chemicals unless your biosafety officer has approved a ducted type for that purpose.

### Using a BSC well

1. Let it run for a few minutes before work (follow your SOP), and check the airflow indicator.
2. Disinfect the work surface before and after (often 70% ethanol or another approved disinfectant).
3. Load everything you need before starting, so you do not move in and out.
4. **Never block the front or rear grilles** with paper, arms or equipment.
5. Work from clean to dirty, in the middle to back of the work surface.
6. **No open flames**: they disrupt airflow and can damage the filter. Use sterile disposable loops or electric incinerators.
7. UV lamps are not a substitute for chemical disinfection.

## Clean benches are not either one

A **laminar flow clean bench** blows HEPA-filtered air **toward you**. It protects the product only. Never use one for biological hazards or chemicals.

## Worked example: which one?

| Task | Use | Why |
|---|---|---|
| Diluting concentrated ammonia | fume hood | vapour hazard to you; sample sterility does not matter |
| Passaging a human cell line | Class II BSC | protect you from potential agents and the cells from contamination |
| Preparing sterile media without hazards | BSC or clean bench | product protection is the goal |
| Using chloroform to extract DNA from a BSL-2 sample | ask your biosafety officer | both hazards: may need a ducted BSC or a split procedure |

## Common mistakes

- **Using a BSC for volatile chemicals.**
- **Using a fume hood for sterile cell culture.**
- **Raising the sash fully** to make reaching easier.
- **Covering the front grille** of a BSC with absorbent paper.
- **Ignoring an alarm** or an out-of-date certification sticker.

## Quick recap

- Fume hood: exhausts chemical vapours outside; protects you, not your sample.
- Class II BSC: HEPA-filtered; protects you, your sample and the environment from biological aerosols, not from chemical vapours.
- Keep work deep inside, sashes low, grilles clear, and check the airflow indicator every time.

Official source: OSHA Laboratories, https://www.osha.gov/laboratories (Checked on 2026-10-23.)


Explain what a chemical fume hood and a biosafety cabinet each protect, and the habits that keep them working.

Fume hoods and biosafety cabinets

The Difference Between Fume Hoods and Biosafety Cabinets

How To Properly Use and Operate a Fume Hood - USC Environmental Health & Safety

Find a published lab spill procedure: search your college's (or any university's) Environmental Health and Safety (EHS) website for "chemical spill procedure".

Write down how that procedure decides between a minor spill (you may clean up if trained) and a major spill (evacuate and call for help). List at least three criteria, such as volume, toxicity, and whether you know what it is.

Draw a one-page flowchart for this scenario: 50 mL of a dilute acid spills on the bench while a classmate is nearby. Include alerting others, PPE, containment, clean-up materials, waste labelling and reporting.

Draw a second branch for: a 1 L bottle of an unknown solvent breaks on the floor and you smell vapour. Where does your flowchart send you?

List four waste streams (for example chemical, biohazard, sharps, broken glass) and, for each, the container type and one item that goes in it.

Write down the emergency phone number your chosen procedure uses and where you would find it posted in a lab.

Optional, only with your instructor in a teaching lab: ask them to show you the spill kit, eyewash, safety shower and waste containers, and add their locations to your card.

> **Awareness level only.** This lesson explains the ideas so you recognise them. It does not qualify you to do this work. Before you handle chemicals, biological materials or lab equipment for real, you need the training your employer or institution requires, and you must work under supervision until they sign you off.

## Why it matters

Lab waste can injure the cleaner who empties a bin, start a fire in a drum, or pollute water if it goes down the drain. Spills turn a controlled procedure into an uncontrolled hazard in seconds. Laws such as the US **Resource Conservation and Recovery Act (RCRA)**, administered by the EPA, regulate hazardous waste, and OSHA rules cover sharps and bloodborne pathogens. Every institution turns these into local procedures, and your job is to know and follow them.

## Waste streams: segregate at the source

The key habit is **putting each item in the right container the moment you are done with it**. Mixing streams can cause reactions, and it makes disposal dangerous and expensive.

| Stream | Container | Examples |
|---|---|---|
| Hazardous chemical waste | compatible, closed, labelled container (often provided by EHS) in a designated accumulation area | used solvents, acid solutions, heavy-metal solutions |
| Biohazardous waste | red or orange biohazard bag in a rigid, lidded container; usually autoclaved or treated | cultures, contaminated gloves and plastics from BSL-2 work |
| Sharps | rigid, puncture-resistant, labelled sharps container | needles, scalpel blades, contaminated glass slides, pipette tips (per local rule) |
| Broken glass (uncontaminated) | cardboard broken-glass box | clean broken beakers |
| Regular trash | normal bin | uncontaminated paper and packaging |

Some specialised streams also exist: radioactive waste (handled by a radiation safety officer), and universal waste such as batteries and lamps.

### Chemical waste rules of thumb

- **Label as soon as the first drop goes in**: "Hazardous Waste", full chemical names (no formulas or abbreviations), and approximate percentages, following your institution's label.
- **Keep containers closed** except when adding waste. A funnel left in the bottle counts as open.
- **Never mix incompatibles**, for example oxidising acids with organic solvents, or acids with cyanides. Check SDS section 10.
- **Use secondary containment** (a tray) under liquid waste.
- **Nothing goes down the drain** unless your institution explicitly approves that specific material.
- Request pick-up before the container is full or the time limit is reached.

### Sharps rules

- **Never recap needles** by hand; drop them straight into the sharps container.
- Do not overfill: close and replace the container at the fill line (often about three-quarters full).
- Never reach into a sharps container or push waste down.
- Pick up broken glass with tongs, forceps or a brush and dustpan, never fingers.

## Spills: decide, alert, contain

Before any spill happens, know where the **spill kit, eyewash, safety shower, fire extinguisher, exits and emergency number** are.

When a spill happens:

1. **Stop and assess.** What is it, how much, where, and is anyone hurt or contaminated?
2. **Take care of people first.** For chemical contact with eyes or skin, use the eyewash or safety shower right away, typically for at least 15 minutes, remove contaminated clothing, and get medical help.
3. **Alert** people nearby and your supervisor.
4. **Decide: minor or major.**
   - **Minor:** a small amount of a known, low-hazard material you are trained and equipped to clean up.
   - **Major:** large volume, highly toxic, flammable near ignition sources, unknown material, anyone injured, or you are unsure. **Leave the area, close the door, and call your emergency number or EHS.** Do not try to be a hero.
5. **For a minor spill:** put on the right PPE, contain the edges with absorbent from the spill kit, work from the outside in, use neutralisers only if your procedure says so, collect the material, and bag and label it as hazardous waste.
6. **Report it**, even if it was small (see module 3).

### Biological spills

For a spill of biological material, your lab's procedure typically has you alert others, leave the area for a set time if aerosols may have formed, then cover the spill with absorbent material, apply an approved disinfectant from the outside in, leave it for the required **contact time**, and dispose of everything as biohazardous waste. Spills inside a biosafety cabinet are cleaned with the cabinet left running.

## Worked example

You knock over a 100 mL beaker of dilute sodium chloride solution at the bench. It is a known, low-hazard material: minor. Tell your neighbour, put on gloves, soak it up with paper towels, wipe the area and dispose of the towels as your lab directs. Now change one fact: the beaker held 100 mL of concentrated nitric acid. It is corrosive and an oxidiser and gives off vapour. Unless you are specifically trained and equipped, treat it as major: alert, leave, close the door, call for help.

## Common mistakes

- **Mixing waste streams** "because the bottle had room".
- **Abbreviations on waste labels** (EtOH, DCM) that responders cannot read.
- **Overfilling sharps containers.**
- **Cleaning a spill you do not understand.**
- **Not reporting a "small" spill.**

## Quick recap

- Segregate waste at the source: chemical, biohazard, sharps, glass, trash.
- Label chemical waste fully, keep it closed and away from incompatibles; nothing down the drain without approval.
- Spills: people first, alert, decide minor or major, contain or evacuate, report.

Official source: US EPA, Hazardous Waste, https://www.epa.gov/hw (Checked on 2026-10-23.)

## Try it

Open the **Do** tab and build your own spill and waste quick-reference card on paper.


Segregate chemical, biological and sharps waste, and follow the decide-alert-contain steps of a spill procedure.

Waste, sharps, and spills

How To: Lab Waste

Emergencies in the Chemistry Laboratory |  ACS College Safety Video #6

Choose PPE, use fume hoods and biosafety cabinets for the right jobs, and follow waste, sharps and spill procedures.