Chemical Safety

what type of chemicals pose physical hazards

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Understanding physical vs. health chemical hazards

To run a safe workplace, it helps to start with a simple framework: chemical hazards fall into two categories—physical hazards and health hazards. OSHA’s Hazard Communication Standard (HazCom), 29 CFR 1910.1200, requires employers to identify chemical hazards, maintain Safety Data Sheets (SDS), ensure proper labeling, and train employees so they understand the risks and protective measures.

Physical hazards relate to how a chemical behaves in the environment—especially whether it can ignite, explode, react violently, or accelerate a fire. Health hazards relate to how a chemical affects the body (e.g., toxicity, irritation, sensitization, carcinogenicity).

When people ask, “what type of chemicals pose physical hazards?” they’re usually trying to pinpoint which products could start a fire, cause an explosion, or create a dangerous reaction if mixed or stored incorrectly. The SDS—especially Section 2 (Hazard Identification) and Section 9 (Physical and Chemical Properties)—is the best source for that information.

What makes a chemical a physical hazard?

Under HazCom (aligned with GHS), a chemical can be classified as a physical hazard when its properties create fire, explosion, or reactive risks. Common physical hazard classes include:

  • Flammables (gases, aerosols, liquids, solids)
  • Oxidizers (gases, liquids, solids)
  • Explosives and self-reactive substances
  • Organic peroxides
  • Pyrophorics (ignite spontaneously in air)
  • Self-heating substances
  • Substances that emit flammable gas when in contact with water
  • Corrosive to metals (a physical hazard because it can weaken containers and piping)
  • Gases under pressure

These classifications appear on compliant labels and SDSs. OSHA expects employers to maintain SDS access and use hazard information to implement controls (e.g., storage compatibility, ignition source control, ventilation, and PPE).

Are all chemicals flammable?

No—not all chemicals are flammable. Many are noncombustible (e.g., some salts, some aqueous solutions) or have flash points so high they aren’t considered flammable under typical conditions.

However, assuming something is “not flammable” can be a serious mistake. Some products that don’t burn easily can still:

  • Feed a fire (oxidizers)
  • Explode (reactives, peroxides, dusts)
  • Release flammable vapors under heat
  • React dangerously when mixed with incompatible materials

Always verify flammability and related properties on the SDS. Key indicators include flash point, boiling point, vapor pressure, and flammable limits (LEL/UEL).

What type of chemicals pose physical hazards? Key categories and examples

Flammable gases, liquids, aerosols, and solids

Flammables are the most recognized physical hazard because they can ignite from heat, sparks, static, or open flame.

Common workplace examples include:

  • Solvents (e.g., acetone, toluene, xylene)
  • Alcohols (e.g., ethanol, isopropyl alcohol)
  • Fuels (e.g., gasoline, diesel)
  • Flammable aerosol sprays (e.g., certain cleaners, lubricants)

Risk increases with poor ventilation, inadequate bonding/grounding during transfer, and improper storage (e.g., near ignition sources).

Oxidizers

Oxidizers may not burn themselves, but they can cause or intensify fires by releasing oxygen or another oxidizing species.

Examples:

  • Hydrogen peroxide (at higher concentrations)
  • Sodium hypochlorite solutions (bleach) under certain conditions
  • Nitrates, chlorates, perchlorates

Oxidizers must be stored away from fuels and organics (including some oils, greases, and solvents). Mixing oxidizers with incompatible materials can lead to rapid heat generation and fire.

Explosives, self-reactives, and organic peroxides

These materials can be unstable and may detonate or rapidly decompose when exposed to heat, shock, friction, or contamination.

Examples include:

  • Certain peroxide-forming chemicals (some ethers) that become hazardous over time
  • Organic peroxide initiators used in plastics/resins
  • Specialized reactive chemicals used in manufacturing and labs

Many of these hazards depend on age, concentration, inhibitors, and storage temperature, which makes inventory tracking and expiration management critical.

Pyrophorics and self-heating substances

Pyrophoric chemicals can ignite spontaneously when exposed to air. Self-heating materials can heat up internally and ignite without an external flame.

Examples:

  • Some metal alkyls used in specialty chemistry
  • Certain reactive metal powders
  • Oily rags can be a real-world self-heating fire scenario in maintenance and painting operations

These require strict handling procedures, proper containers, and training.

Water-reactive chemicals (emit flammable gas)

Some substances react with water to generate flammable gases (often hydrogen) and heat.

Examples:

  • Alkali metals (e.g., sodium, potassium)
  • Certain hydrides and reactive metal compounds

Even small amounts of moisture can create a dangerous condition, so storage and spill response plans must account for humidity and water-based suppression limitations.

Corrosive to metals and gases under pressure

These hazards can be overlooked because they don’t always “look” dramatic—yet they can cause catastrophic failures.

  • Corrosive to metals chemicals can weaken drums, piping, valves, or secondary containment.
  • Gases under pressure can rupture cylinders if exposed to heat or physical damage, and rapid release can create projectile hazards and asphyxiation risks.

How to tell if a chemical is a health hazard (and why the distinction matters)

Physical and health hazards often overlap. For example, a solvent can be flammable (physical) and toxic (health).

A helpful rule of thumb is embedded in how people ask it: “a chemical is considered a health hazard if the chemical can cause acute or chronic health effects.” Under OSHA HazCom, health hazards include categories like acute toxicity, skin corrosion/irritation, serious eye damage, respiratory sensitization, carcinogenicity, reproductive toxicity, and specific target organ toxicity.

Why it matters:

  • Engineering controls may differ (ventilation for vapors vs. segregation for reactives)
  • Storage compatibility is especially critical for physical hazards
  • Emergency response differs (firefighting media, spill isolation distances, reactive spill procedures)

What are some common chemical hazards in the workplace?

Most workplaces encounter a mix of health and physical hazards. Common examples include:

  • Flammable liquids used for cleaning, degreasing, painting, and printing
  • Compressed gases (welding gases, CO₂, nitrogen, propane)
  • Corrosives (acids and bases) that can also corrode metals and generate heat when diluted
  • Oxidizers used for sanitation, water treatment, or industrial processes
  • Reactive chemicals in labs, maintenance shops, and manufacturing

OSHA’s 29 CFR 1910.1200 requires that employees have ready access to SDSs for these products and be trained on the hazards in their work area, including protective measures and emergency procedures.

SDS management and OSHA compliance: practical steps

Use the SDS to identify physical hazard controls

Key SDS sections for physical hazards include:

  • Section 2: GHS classification, signal word, hazard statements
  • Section 5: Fire-fighting measures
  • Section 7: Handling and storage (including incompatibilities)
  • Section 9: Physical/chemical properties (flash point, vapor density, etc.)
  • Section 10: Stability and reactivity (conditions to avoid, incompatible materials)

Build a chemical inventory that supports safe storage

Physical hazards are often driven by where and how chemicals are stored and used (e.g., oxidizers next to flammables, aging peroxide-formers, untracked aerosols in hot areas).

SwiftSDS can help by centralizing SDS access, supporting OSHA HazCom documentation needs, and providing chemical inventory management features (locations, quantities, and expiration dates) so teams can reduce incompatible storage and keep time-sensitive chemicals from becoming a surprise hazard.

You can also create consistent internal access paths for workers, such as a dedicated SDS page on your intranet: SDS library.

Conclusion: identify physical hazards before they ignite, explode, or react

Physical hazards aren’t limited to “things that burn.” What type of chemicals pose physical hazards includes flammables, oxidizers, explosives/self-reactives, organic peroxides, pyrophorics, water-reactives, gases under pressure, and even chemicals corrosive to metals. Pair that understanding with OSHA HazCom requirements (29 CFR 1910.1200), and you have a strong foundation for safer storage, handling, and emergency response.

If you can’t quickly find the current SDS and hazard classification for a product, you can’t reliably control its physical hazards.

Call to action: Want to strengthen your HazCom program and make SDS access fast and audit-ready? Explore SwiftSDS to centralize your SDS library, track chemical inventory risks, and give employees mobile access to the right SDS at the point of use.