Inorganic gases

Combustion is the main source of inorganic gases indoors. Other sources are human breathing, the use of ultraviolet light technology or entry from the outside.

Carbon monoxide (CO) is a colourless and adourless gas emitted as a result of the incomplete combustion of fossil fuels and biofuels. In households, it usually comes from gas kitchens, boilers, tobacco smoke, or from outside, mainly because of vehicle traffic.

CO penetrates the body through the lungs, causing a decrease in the oxygen transport capacity of the blood, as it tries to transform to CO2. The effects are that it steals oxygen from the blood in detriment to oxygenation of organs and tissues, as well as cardiac dysfunction, damage of the nervous system, headache, dizziness, vomiting and fatigue.

Also, it has consequences on the climate, since it contributes to the formation of greenhouse gases: its average life in the atmosphere is about three months, which allows its slow oxidation to form carbon dioxide (CO2), process during which ozone (O3) is also generated.

Carbon dioxide (CO2) is a colourless, odourless gas that forms in all those processes where combustion of carbon-containing substances takes place.

In non-industrial interiors its main focus is human breathing and smoking; although the levels of carbon dioxide can also be increased due to the existence of other combustion (kitchens and heating) or the proximity of traffic routes, garages or certain industries.

The concentration of carbon dioxide in an indoor environment can provide information on different aspects and circumstances of a building such as the possibility of harmful effects on the health of its inhabitants.

The main effects of this excess gas are oxygen removal. When the proportion of carbon dioxide in the air we breathe is 700ppm (0.07%), there are already symptoms of fatigue, loss of performance, headache and an increase in respiratory rate.

Ozone in the troposphere acts as an ultraviolet ray filter. However, on the earth’s surface or inside spaces, it works as an air pollutant.

Higher concentrations of ozone appear when there are higher solar radiation and emissions of volatile organic compounds. Thus, the volatile organic compounds are capable of reacting and producing photochemical oxidants that impel the creation of ozone.

In enclosed spaces, the main ozone precursors are the volatile organic compounds together with the presence of UV light (lights, electric shock and photocopiers).

Ozone penetrates through the respiratory tract and due to its highly oxidizing properties it causes the irritation of the mucous membranes and the lung tissues, which leads to irritation of eyes, cough, headaches and chest pain, among other effects.

The World Health Organization (WHO) in its air quality guide associates daily mortality with ozone levels.

The use of ozone-generating air purifiers may worsen ambient air instead of improving it as the effectiveness of eliminating pollutants in the gas phase (nitrogen dioxide, formaldehyde) is low.

Nitrogen dioxide (NO2) is mainly due to the oxidation of nitrogen monoxide (NO) that occurs in combustion of the engines of the vehicles, essentially diesel. Nitrogen monoxide emitted by engines, once in the atmosphere, is oxidized and transformed into nitrogen dioxide.

NO2 in nature is produced by forest fires or volcanic eruptions. It is also produced naturally by the decomposition of organic nitrates. However, the total volume that appears naturally is infinitely lower than what is produced by the effect of mankind.

WHO warns of the serious consequences that a very high concentration of nitrogen dioxide has for our health. Children, the elderly, and people with health problems (such as asthma, heart and lung diseases) would be the most affected.

For human health, its effects mainly include airway inflammation, organ disorders, such as liver or spleen, or systems, such as the circulatory or immune system, which in turn cause pulmonary infections and respiratory insufficiencies.

On the other hand, nitrogen dioxide also provokes the formation of particulate dust, especially fine PM2.5 particles, which are the most harmful. In reaction with sunlight, UV is also a precursor of ozone formation in reaction to volatile organic compounds such as formaldehyde, which potentially worsens the aforementioned consequences on health.