Breathing into a Plastic Bag: Can My Breath Remain Indefinitely Sealed?

The question of whether breathing into a sealed plastic bag and storing it in an airtight box can keep your breath sealed indefinitely is interesting. However, based on scientific principles, it's unlikely to be the case. In this article, we will explore the reasons behind this, including the composition of human breath, the integrity of sealable plastic bags, gas diffusion, and microbial activity.

Understanding the Composition of Breath

Human breath is primarily composed ofnitrogen (about 78%), oxygen (about 21%), and small amounts of carbon dioxide, water vapor, and other gases. Given the limited space and limited supply of oxygen in a plastic bag, the composition will start to change over time. The oxygen in the bag would gradually be consumed by any present aerobic bacteria, leading to a change in gas composition.

The Role of Seal Integrity

Sealable plastic bags are designed to be airtight, but they are not perfectly impermeable. Over time, even the best sealable bags can allow some gas exchange with the external environment. This means that gases could slowly escape from the bag, leading to a reduction in the total volume of air inside the plastic bag.

Gas Diffusion Through Plastic

Gases can still diffuse through the plastic material, albeit very slowly. The rate of diffusion is influenced by factors such as temperature, humidity, and the type of plastic used. Even with the slowest possible diffusion, the gases inside the bag would eventually interact with the surrounding environment, causing a gradual loss of gases.

Microbial Activity

If there are any microorganisms present in the bag or the container, they will metabolize the gases, particularly oxygen. This microbial activity would alter the composition of the air inside the bag. For instance, aerobic bacteria would consume the oxygen and produce carbon dioxide, leading to a gradual change in the internal gas composition.

Conclusion

While the breath would remain in the bag for a significant period due to the airtight seal, it would not last indefinitely. Factors such as gas exchange, permeability of the bag material, and microbial activity would eventually lead to changes in the gas composition inside the bag. Understanding these processes can help us comprehend why it's essential to consider the limitations of our containers when storing gases or other substances.

For more information on the technical aspects of airtight containers, consult the following sources:

Ken Saladin, "A Great Container for a Gas Bubble is a Block of Ice" Research on the permeability of plastic materials Studies on microbial activity in sealed environments

By understanding these scientific principles, you can make more informed decisions about which containers to use for storing various substances.