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It is at this time of the year that we in the Protestant Reformed Churches and other Reformed churches that hold to the same Church Order (Art. 67) observe our annual Day of Prayer. We do so for no small reason. Each of us is truly dependent upon God’s daily provisions for our earthly existence. Though North American society has drastically changed in the past one hundred years, from the farmland to the office cubicle, we are no less dependent upon the physical creation for our daily existence. Long ago, in the era of the small family farm, people of God were more conscious of their dependence upon good soil, sufficient rainfall, and plenteous sunny, warm weather, and thus, more readily noted God’s providential care. Today, we and our children can just open the refrigerator, or dash to the local grocery store to easily obtain our food and drink for another meal. Without much consideration as to where our food really comes from, we gather around the table and enjoy the bounties of this earth. Perhaps, in the early twenty-first century in North America we need a Prayer Day service more than ever before, to remind us of our dependence on God.

Last year, we examined water—a substance of vital importance for our physical existence and worthy of consideration in connection with our annual Day of Prayer. In this article we will examine air—and more particularly its fundamental element, oxygen—and note our absolute dependence in our every breath for this indispensable gift of God. As we observe the annual Day of Prayer, calling on Almighty God to grant us what we need both physically and spiritually, may we give earnest attention to His good provisions in the creation for our physical needs. In an age in which we have an abundance of physical things, we may be tempted to be proud and forget or deny God (Prov. 30:7-9). It is our hope that this series of articles may stimulate us to a renewed consciousness of our utter dependence on God for our physical (and most assuredly, spiritual) life.

To help us grow in our understanding of our dependence on God’s government of the creation, let us, in this and future articles, look at three vital processes in which oxygen plays a significant role: respiration, combustion, and oxidation.


Under normal circumstances man cannot live for much more than five minutes without oxygen. On average, humans inhale approximately 7-8 liters of air per minute, or 11,000 liters of air per day. The lower layer of the atmosphere in which we live (up to 10 miles in altitude) contains on average 21% oxygen gas, 78% nitrogen gas, and 1% other gases. Therefore, of the 7-8 liters of air we inhale per minute, about 1.5 liters is oxygen. Only a small portion of this amount is actually used by our body (we use about 5% of the total air we inhale). The rest is exhaled, which is why mouth-to-mouth resuscitation is possible. By the end of each day our lungs have absorbed approximately 550 liters of oxygen. Picture 275 two-liter bottles on your kitchen floor; this is the volume of oxygen each of us uses per day! When one considers the nearly 7 billion people on the earth today, to say nothing of all the animals that also use oxygen through respiration, one is simply overwhelmed with the massive volume of oxygen that must always be present in the atmospheric storehouse to supply us with the necessary oxygen to survive.

God in His wisdom designed a pair of processes—respiration and photosynthesis—that by His providence give ample oxygen for us and the animals of creation to breathe. As fast as we remove oxygen from the atmosphere via respiration, photosynthetic organisms such as plants, algae, and cyanobacteria convert carbon dioxide (a waste product of our respiration) into a fresh, new oxygen supply. Organisms that contain the green-colored, “solar-powered” chloroplast organelles are the best-known “recycling facilities” on the planet. All through the day, as humans (and animals) use oxygen for their daily existence, the chloroplasts, powered by sunlight, convert the waste carbon dioxide that we exhale back into oxygen gas (and simultaneously produce sugar products that are stored in the plant fibers, which we, incidentally, will use later on as our food supply). By this marvelous pair of processes, the oxygen supply in the atmosphere remains fairly stable so that we always have sufficient oxygen to breathe.

This “recycling” of carbon dioxide to produce fresh oxygen is accomplished primarily by the tiny algae and cyanobacteria in the creation. With 70-80% of oxygen production performed by these marine organisms, we ought to be encouraged to take good care of our marine ecosystems, as they contribute significantly to our oxygen supply.

Those of us who have difficulty breathing due to allergies or some other respiratory ailments are perhaps more conscious of the air God gives us to breathe. But we all ought to rise from our bed each morning and give thanks to God for the good gift of air and the ability to breathe. What an absolutely marvelous and intertwined creation God governs every moment of the day so that we can physically exist!


What further illustrates the amazing design in God’s creation is how the body is able to “absorb” oxygen via the lungs in order to support all of our life functions, and simultaneously exchange it for the harmful carbon dioxide that is produced as a by-product of our life processes.

Oxygen is absorbed into our bloodstream by an amazing process called diffusion. Diffusion is the process by which molecules move through a membrane from areas of higher pressure to areas of lower pressure. In order for oxygen to pass through the walls of the alveoli—the tiny air sacs at the end of the respiratory tubes that form the bulk of our lungs—into the capillaries of the bloodstream, the pressure in the alveoli must be greater than the pressure in the bloodstream. Atmospheric pressure at sea level is approximately 760 torr (a unit of measurement for pressure). Oxygen is approximately 21% of atmospheric air. Atmospheric oxygen pressure, therefore, is about 160 torr. Pressure of oxygen in your lungs is a bit lower at about 100 torr due to various factors, including higher water content in the lungs, and consequently less place for oxygen molecules. Venous blood (blood returning to the lungs from the cells) has a lower oxygen pressure (about 40 torr) because it has recently given up its oxygen to various cells that needed it throughout the body. Due to this pressure difference of about 60 torr, oxygen will move through the capillary-alveolar cell membranes, thus exiting the lungs and entering the bloodstream via the capillaries.

Anything that affects this pressure difference will in turn affect the amount of oxygen that can cross into the bloodstream. One factor is the oxygen pressure of the atmospheric air. As one climbs to a higher altitude, the atmospheric pressure decreases because there are fewer air molecules at higher altitudes. Consequently there will be a lower atmospheric oxygen pressure. Therefore, less and less oxygen will be ‘pushed’ into the bloodstream. This explains why we feel ‘out of breath’ as we hike in higher altitude terrain.

What we likely take for granted is the ease with which we breathe. This is because it takes only about 1 torr of pressure difference between the pressure in the atmospheric air and our lungs in order to inflate the balloon like alveoli that comprise our lungs. However, to cause each spherical alveolus to inflate and expand requires much more pressure than the 1 torr that we use.

The reason that our alveoli require a large amount of pressure to be inflated is that they are coated in a water based fluid lining. A drop of water has a tremendous surface tension, due to the attractive forces between its component molecules, thus decreasing its surface area. Consequently, the alveoli naturally collapse, helping to expel carbon dioxide from our lungs. In this way the fluid lining serves an important role in respiration. However, this fluid will also cause the alveoli to resist expanding. But God in His wisdom also created another chemical to be present in the lungs to act as a surfactant, which minimizes the surface tension of the fluid layer. This allows the alveoli to inflate much more easily. Without such an important chemical, we would have to work much harder to catch a breath of fresh air. A lack of this surfactant is one of the key causes of death in premature babies. This vital surfactant is produced during the 24th-35th weeks of gestation, which means that babies born before the 35th week will have difficulty breathing.

God’s Good Provisions

This kind of intricate detail is not the exception in God’s creation. It is the norm. While many in the world have deceived themselves into believing that the human body with all of its intricacies somehow developed on its own over time through an evolutionary process, we by the grace of God see this great beauty and wisdom as the handiwork of God.

God provides us with the good gifts we need in order to live in this world. He wisely created, and continues every day to govern the processes and systems of the creation so that they work in an intricate fashion to enable us to live and thrive. From the vital respiration-photosynthesis relationship to the tiny surfactant molecule in the alveoli that makes them inflate easily, we can see God’s marvelous ways of providing us the oxygen we need to fuel our cells.

God provides for us in similar detailed ways for all of our physical needs. When we get food from the grocery store, we must recognize that the right amount of rain, sunshine, and mineral content in the soil was sovereignly governed by God so that all these factors perfectly worked together to assure that crops could grow. God in His goodness to us provides us with all that we need for our physical life through many such intricate and interrelated means.

We have so much reason to give thanks to God for His good provisions to us each day. As we gather for our annual Day of Prayer, may we rightly consider all God’s good provisions for us. Thanks be to God, who gives us eyes to see His handiwork in creation and confident hearts to trust His willingness and ability to provide for us throughout this year and the years to come.