Dr. Krishna, you say the atoms and molecules of our bodies are recycled after death. But some people cremate the bodies. Then what happens to the particles of the body?
Krishna:
Burying and cremation might follow different routes of recycling but recycling does occur after death.
A crematorium (plural: crematoria or crematoriums) is a facility or building equipped with a specialized furnace—known as a crematory, retort, or cremation chamber—used to burn and reduce human or animal remains to ashes.
The Cremator is a high-temperature, purpose-built furnace—typically operating between 1,400°F and 1,800°F (760°C to 980°C)—that vaporizes organic tissue and bone fragments during a process lasting about two hours.
The body is placed in a specialized furnace called a retort.
The extreme heat causes tissues, water, and organic molecules (fats, proteins, DNA, and carbohydrates) to rapidly break down and vapourize.
Cremation breaks down the human body into gases that enter the atmosphere and mineral ash that can return to the soil, following the laws of thermodynamics where matter transforms rather than disappears.
What happens to the gases
Water Vapour & Steam: Roughly 65% of the body's mass (mostly water) evaporates as steam during the high-temperature burn.
Carbon Dioxide & Nitrogen: About 18% of the mass forms carbon dioxide, and a small percentage turns into nitrogen and trace oxides, which disperse directly into the atmosphere.
Carbon, hydrogen, oxygen, and nitrogen from soft tissues and organs combine with oxygen to form carbon dioxide and water vapour (superheated steam), which rise and exit through the crematorium chimney into the atmosphere.
Filtration: While modern crematoriums use scrubbers and filters to capture heavy metals or particulate soot, gases like carbon dioxide and water vapor pass freely into the air.
What happens to the ash
Composition: The remaining material consists mostly of stable calcium phosphate and mineral crystals from the skeletal structure.
The soft parts and organic components burn away completely.
What is left behind is the hard mineral skeleton—primarily calcium phosphate and other bone minerals.
Return to Nature: When scattered in gardens, forests, rivers, or soil, the mineral ash can eventually be absorbed by plants and integrated into the local ecosystem, though concentrated bone ash has a high pH and low organic nutrient content compared to natural decomposition methods.
Alternative options: For a more direct biological recycling process into nutrient-rich soil, alternatives like natural burials or human composting offer zero-emission decomposition.
Medical and Dental Metals: Prosthetics, titanium joint replacements, rods, and dental fillings do not burn away. Many crematoria partner with specialized recycling programs (such as Orthometals) to collect, sort, and melt down these metals into raw industrial materials. They are recycled.
However, it’s essential to recognize that this method has environmental implications worth considering.
Cremation requires a significant amount of energy. The process involves heating a cremation chamber to temperatures. This takes place over several hours. This energy-intensive process contributes to greenhouse gas emissions and the depletion of natural resources.
The cremation process releases atmospheric emissions, including carbon dioxide (CO2), nitrogen oxides (NOx), and particulate matter. While modern crematories have pollution control technologies to minimize emissions, some pollutants may still escape into the environment, contributing to air pollution and climate change.
One of the cremation’s most concerning environmental impacts is the release of mercury vapor. Dental fillings containing mercury (amalgam) are often not removed from deceased bodies before cremation. As a result, mercury vapor is released into the air, posing a risk to the environment and human health.
Cremation requires using materials such as caskets, urns, and clothing, all of which can have their environmental impacts. The production of these items consumes resources and energy, and many are not biodegradable.
Cremation can also indirectly impact the environment by influencing burial practices. As cremation becomes customary, it may reduce traditional burial practices, often involving using land for cemeteries. Some argue that we could repurpose the ground for more environmentally friendly uses.
Natural burial aids in conserving natural resources, reducing carbon emissions, protecting worker health, and the restoration and/or preservation of habitats. Additionally, it pays special attention to returning the body to the earth in a safe way that is simple and natural, allows for more significant family interaction, and is a fraction of the cost of conventional burial.
So environmentalists are suggesting green burial now.
During an open-air Hindu cremation on a wooden pyre, the physical body is transformed through fire (Agni), breaking down into soft tissue, bone, and ash.
What happens to the body material
Soft tissues and fluids: The intense heat of the wood fire vapourizes and consumes all soft tissues, organs, and bodily fluids, returning them to the air and environment.
Bones and teeth: Bone tissue (composed largely of inorganic calcium phosphate) does not completely vaporize. Instead, the skeletal structure dries out, fractures, and remains behind as white or grey calcified bone fragments.
Ashes (bhasma): The remaining charcoal, wood ash, and smaller mineral residues mix together on the pyre.
Post-cremation collection and immersion
Collection of remains (Asthi Sanchayan): On the third or fourth day following the cremation, family members (typically male relatives or the chief mourner) return to the pyre site once the embers have cooled. They gather the remaining bone and mineral fragments (asthi).
Immersion (Asthi Visarjan): These remaining bone and ash materials are traditionally taken to be immersed in a sacred body of water, such as the Ganges, Krishna, Godavari or any local rivers and the sea, symbolizing the complete return of the physical elements (earth, water, fire, air, and space) back to nature for recycling.
Nothing is destroyed; by the First Law of Thermodynamics, matter and energy simply change form.
The atmospheric cycle (Gases):
The water vapour released into the air enters the global carbon and water cycles.
Plants absorb the carbon dioxide through photosynthesis, converting the carbon into plant tissue, flowers, or crops, which then re-enter the food chain for animals and humans.
The soil and Earth cycle (solid remains):
When cremains are scattered in gardens, forests, rivers or memorial parks, or buried in the ground, the calcium phosphate and trace minerals (like sodium and potassium) leach into the soil.
Plant roots absorb these minerals and nutrients, integrating the atomic building blocks of the body directly into new flora, trees, and localized ecosystems.
So when a human body is burned (cremated), intense heat transforms the organic matter and minerals through thermal breakdown and combustion, returning the elements back into Earth’s natural cycles.
When a body is buried, it "recycles" through natural biological and chemical decomposition, though the speed and process depend heavily on whether it is a traditional burial or a green/natural burial.
The stages of natural decomposition in the Earth
Cell rupture and autolysis (hours to days):
Right after death, cells stop receiving oxygen. Enzymes inside the cells start breaking down cell membranes from the inside out, releasing nutrient-rich fluids.
Microbiome takeover (days to weeks):
The body's internal microbiome (bacteria and fungi in the gut and respiratory system) no longer restrained by an active immune system begins to consume soft tissues from the inside. They break down proteins, carbohydrates, and lipids, producing gases like carbon dioxide, methane, and ammonia.
Soil organisms and microbes (weeks to years):
Bacteria, fungi, and soil-dwelling organisms enter the body (if accessible) and break the remaining organic matter down into basic chemical building blocks—such as nitrogen, phosphorus, potassium, and carbon.
Nutrient return to the soil:
These elements enrich the surrounding soil, acting as a natural fertilizer that feeds nearby plant and tree roots. What remains after soft tissues dissolve are bones, which slowly mineralize and break down over many decades.
"Earth to earth, ashes to ashes, dust to dust".
Whatever way it is done, you have to return the matter and energy of your body to the Universe that gives you these things just for a lifetime. Because they belong to the source, not you!
And they go to other things afterwards, both living and non-living, and belong to them temporarily until the universe takes them away again for recycling.
Then what is yours? Nothing in reality!
There is no I, me, or mine. There is just a temporary feeling.
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