Both nitrogen dioxide and nitric oxide are also produced in combustion.  Unlike carbon monoxide which cannot be detected, nitrogen oxides are yellowish-brown in colour and are the major contributor to haze in city air, injury to plants and destruction of forests near industrial areas.  Oxides of nitrogen are emitted by internal combustion engines, power stations, furnaces, cars and fertilizers.  Exposure to oxides of nitrogen may lead to death from pulmonary lesions (due to reduced partial oxygen pressure in the lungs); sudden death from spasms of the lungs and respiratory failure; pulmonary oedema; or inflammatory responses in the bronchiole system.

Sulfur oxides are another common by-product of combustion and released into the environment.  Exposure to air contaminated with sulphur dioxide will cause irritation of the eyes, nose, throat and lungs, resulting in choking and coughing.  Individuals with asthma are particularly sensitive to sulphur dioxide.

Both nitrogen oxides and sulphur oxides are primarily irritants to human health.  The by-products of major concern are the polycyclic aromatic hydrocarbons (PAHs), which have been identified as carcinogenic, mutagenic and teratogenic.  Polycyclic aromatic hydrocarbons are chemical compounds that consist of fused aromatic rings, whose resulting structure determines whether they are non-toxic or highly toxic.  Polycyclic hydrocarbons are not only caused by combustion of fossil fuels, but are also formed by incomplete combustion of wood, coal, diesel, fat, tobacco or incense.

To Be Continued…

Disruption of the natural carbon cycle occurs with human intervention and the results of exponential growth in the world’s population.  Burning of fossil fuels releases stored carbon, increasing the overall percentage of carbon dioxide in the atmosphere.

Today, the debate continues on whether global warming is myth or fact.  However, what is certain is that combustion of fossil fuels through industrial activities, vehicle exhaust fumes, smoking, use of petrochemical products in buildings, etc, produces by-products which affect the quality of the air which humans breathe.  These by-products are tiny particles, whose chemical composition, particle shape and size are all factors that determine how they impact human health.

The primary by-product of burning fossil fuels is carbon dioxide.  However, this exists naturally in the carbon cycle.  Of more significance in impacting human health are the by-products of carbon monoxide, nitrogen oxides, sulphur oxides and hydrocarbons.  Suspended particles from these compounds can combine in the atmosphere to form tropospheric ozone, the major constituent of smog.

Carbon monoxide is a deadly toxic gas, undetectable by smell that can harm or kill animals, plants and people.  It is produced during incomplete combustion of fossil fuels.  Inhalation is poisonous and causes headaches, dizziness, nausea, shortness of breath, light-headedness and, in extreme cases, death.  People with heart disease will be susceptible to more stress on the heart.  Motor vehicles are the primary source of carbon monoxide.

To Be Continued…

Carbon in Nature

The three most important substances that make life possible are water, oxygen and carbon dioxide.  The primary structural and functional element in all living things is carbon.  All carbon in protein, fat, carbohydrate and other organic molecules in living things is derived from atmospheric carbon dioxide.  Without atmospheric carbon dioxide, life as we know it would not be possible.

The carbon cycle is the biogeochemical cycle by which carbon is exchanged between the biosphere, geosphere, hydrosphere and atmosphere of our planet Earth.  Carbon is stored in four major reservoirs:

• The atmosphere
• The biosphere (including freshwater systems and ground soil)
• The oceans (including dissolved inorganic carbon)
• The sediments (including fossil fuels)

Carbon is exchanged between these reservoirs via sequences of various chemical reactions and biological processes.

Carbon exists in the Earth’s atmosphere primarily as the gas carbon dioxide.  Although it is a very tiny percent of the atmosphere (approximately 0.04%), it plays an essential part in supporting life.  In particular, plants absorb carbon dioxide in the presence of sunlight to produce carbohydrate, and release oxygen into the air.  This process is known as photosynthesis, and provides plants with the key organic compounds required to support life.

In nature, carbon can then be released naturally back into the cycle in many different ways with the most common being respiration, decay of animal and plant matter, and the release of dissolved carbon dioxide from the oceans by marine life.

To Be Continued…..