Chemicals are everywhere. Every material you can touch, breathe, drink, or see is made of chemical substances, from the nitrogen in the air around you to the calcium in your bones. The word “chemical” often carries a negative connotation, but it simply refers to any substance with a defined molecular composition. Here’s where you’ll find them in daily life, in nature, and in your own body.
The Air You Breathe
Earth’s atmosphere is a mixture of gases, each one a distinct chemical. Nitrogen makes up 78% of the air, oxygen accounts for nearly 21%, and argon fills most of the remaining 1%. Carbon dioxide sits at about 0.042%, a small fraction that plays an outsized role in regulating the planet’s temperature.
Beyond those major players, the atmosphere contains trace gases measured in parts per million: neon at 18 ppm, helium at 5 ppm, methane at nearly 2 ppm, and hydrogen at about half a ppm. Even ozone, the compound that shields life from ultraviolet radiation, exists at just 0.07 ppm. Ammonia, nitrogen dioxide, and carbon monoxide appear in amounts so small they’re labeled as trace. Every breath you take pulls in this entire cocktail.
Inside the Earth’s Crust
The ground beneath your feet is dominated by just two elements. Oxygen accounts for 46.6% of the crust by weight, and silicon makes up 27.7%. Together they form silicate minerals, the building blocks of most rocks and sand. Aluminum comes in third at 8.1%, followed by iron at 5%, calcium at 3.6%, sodium at 2.8%, potassium at 2.6%, and magnesium at 2.1%. Every other element on the periodic table, from gold to uranium, shares the remaining 1.5%.
These crustal chemicals are the raw materials for everything from steel (iron) to fertilizer (potassium) to the aluminum in soda cans. Mining and refining simply concentrate what the Earth already contains.
In Your Own Body
You are, quite literally, a collection of chemicals. Four elements make up 96.2% of your body weight: oxygen, carbon, hydrogen, and nitrogen. Oxygen is the heaviest contributor because water molecules, which fill every cell, are mostly oxygen by mass. Carbon forms the backbone of every protein, fat, and strand of DNA. Hydrogen and nitrogen round out the group.
Beyond those four, your body relies on iron (critical for carrying oxygen in blood), iodine (used by the thyroid gland), and at least 15 trace elements that each account for less than 0.01% of your weight. That list includes zinc, copper, selenium, chromium, cobalt, and manganese. They appear in tiny amounts, but many are essential for enzymes and hormones to function.
Under the Kitchen Sink
Household cleaning products are some of the most chemical-dense items in a typical home. Bleach is a solution of sodium hypochlorite dissolved in water, and it works by attacking and destroying bacteria, viruses, and mold on contact. You’ll find it in disinfectant sprays, toilet bowl cleaners, and tile and grout products.
Ammonia, a strong-smelling gas dissolved in water at concentrations of 5 to 10%, appears in glass cleaners, oven cleaners, and all-purpose sprays. It boosts a cleaner’s ability to cut through grease. Mixing bleach and ammonia produces toxic fumes, which is why labels warn against combining the two.
Detergents rely on chemicals called surfactants, short for “surface active agents.” These molecules bond to both water and grease at the same time, breaking up grime so water can wash it away. Dish soap, laundry detergent, and hand soap all depend on variations of the same principle.
In Your Food
Every food is a package of chemicals. An apple contains water, fructose, malic acid, fiber, and dozens of vitamins and minerals. Processed foods add more to the list. Preservatives like butylated hydroxyanisole (BHA) slow the breakdown of fats so packaged foods last longer on shelves. Emulsifiers keep oil and water from separating in things like salad dressings and ice cream. Synthetic color additives give candies and beverages their bright hues.
The FDA reviews these added chemicals for safety. Some have come under renewed scrutiny: FD&C Red No. 3, a red food dye, had its authorization revoked in January 2025, and BHA is currently under the agency’s post-market review program. The ingredients panel on any packaged food is essentially a list of the chemicals inside it.
In Your Tap Water
Drinking water contains both intentionally added chemicals and trace contaminants. Chlorine or chloramine is added at treatment plants to kill pathogens. Fluoride is added in many systems to support dental health. Beyond those, the EPA regulates over 65 chemical contaminants in three categories: inorganic compounds like arsenic, nitrate, and mercury; volatile organic compounds like benzene and toluene; and synthetic organic compounds like pesticide residues and industrial solvents.
Each contaminant has a maximum allowed level. Arsenic, for example, is capped at 10 parts per billion. Nitrate is limited to 10 milligrams per liter. For chemicals known to cause cancer, the EPA sets the safety goal at zero, meaning any detectable amount is considered undesirable even if small concentrations are permitted as practically achievable limits.
In Personal Care Products
Shampoos, lotions, sunscreens, and cosmetics contain a wide range of synthetic and naturally derived chemicals. Parabens act as preservatives to prevent bacterial growth in products that sit on bathroom shelves for months. Phthalates help fragrances last longer and make plastics more flexible in packaging. Alpha hydroxy acids and beta hydroxy acids exfoliate skin in anti-aging creams and acne treatments. Diethanolamine serves as a foaming agent in soaps and cleansers.
Color additives give makeup its pigments, and fragrance formulations can contain dozens of individual chemical compounds blended together. The FDA maintains a list of prohibited and restricted cosmetic ingredients, but many chemicals in personal care products are used at the manufacturer’s discretion within broad safety guidelines.
How Chemicals Are Tracked and Labeled
In workplaces, chemicals are identified through Safety Data Sheets, standardized 16-section documents that accompany every hazardous substance. These sheets classify chemicals by health hazards (like whether they’re toxic or irritating) and physical hazards (like whether they’re flammable or explosive). Every product must carry a label with the same identifier that appears on its Safety Data Sheet, so workers can quickly look up safety information.
For consumers, the information is simpler but follows the same logic. Ingredient lists on food, cleaning products, and cosmetics name the chemicals inside. Hazard symbols on household products warn about corrosive, flammable, or toxic contents. The chemicals themselves aren’t hidden. They’re listed on nearly every product you buy.