Environmental Science Popularization: Pros and Cons of Ozone (Part 1)
When it comes to ozone, the initial impression is invariably unfavorable: the term ‘odorous’ evokes its pungent smell, while ‘oxygen’ conjures associations with its chemical properties of ‘oxidation, aging, and instability.’ Moreover, environmental issues such as ‘ozone pollution’ and ‘ozone layer depletion’ are often linked to this substance. But in reality, is ozone truly such a ‘bad guy’?
In our previous discussion, we explored the history and current status of ozone, while also briefly distinguishing between ‘good ozone’ and ‘bad ozone.’ This time, we’ll delve into why ozone is both adored and reviled, evaluating its merits and flaws. In the earlier article, we first set the record straight for ozone—this seemingly’ bad’ substance is actually a good friend to humanity, having played an indispensable role in protecting us for generations.
Earth’s Umbrella
In the scorching summer heat, pedestrians hold umbrellas to shield themselves from ultraviolet (UV) radiation. Meanwhile, ozone in the stratosphere acts as Earth’s protective umbrella, blocking most of the sun’s UV rays. UV radiation causes severe damage to biological tissues, as high-energy UV rays can damage DNA and RNA, leading to denaturation. In the early Earth, the absence of an oxygen-rich atmosphere and ozone allowed direct exposure to high-energy UV sunlight. Unable to withstand UV damage, all life had to rely on aquatic protection, hiding beneath the surface of oceans and lakes. As primitive algae began synthesizing oxygen through photosynthesis, atmospheric oxygen levels gradually increased. Photochemical reactions further elevated ozone concentrations, absorbing large amounts of UV radiation. This gradual process eventually enabled life to emerge on land.
The ozone layer commonly referred to is the ozone present in the atmosphere at altitudes of 20–26 km (some sources suggest 20–30 km) within the stratosphere. In this atmospheric layer, oxygen and ozone maintain a dynamic equilibrium through various photochemical reactions. Ultraviolet radiation is absorbed by ozone at high altitudes, which not only contributes to atmospheric warming but also protects Earth’s organisms from damage caused by far ultraviolet radiation.
The ozone-oxygen reaction equilibrium in the ozone layer is susceptible to solar activity or certain chemical substances, leading to a decline in ozone levels. For every 1% reduction in ozone, ultraviolet radiation increases by 2%, resulting in a 5% to 7% rise in skin cancer incidence and a 0.2% to 0.6% increase in cataract rates. The heightened ultraviolet intensity not only jeopardizes human health but also disrupts ecological balance and impacts various aspects of human production and daily life. It is no exaggeration to say that the ozone layer enabled the evolution of life from marine to terrestrial environments and made the emergence and continued survival of humanity possible.
A good friend of mankind
In addition to forming the ozone layer, the benefits of ozone to human beings are also widely used in the production and life of human beings, such as sterilization, oxidation, decolorization and deodorization.
Ozone rapidly oxidizes and destroys the cellular structures of bacteria, viruses, and fungi, thereby purifying air and water sources. Its disinfection and sterilization capabilities exhibit broad-spectrum efficacy (capable of eliminating nearly all pathogens, viruses, molds, protozoa, and oocysts), high efficiency (uniform dispersion without dead zones and rapid action), high cleanliness (producing only oxygen with no harmful residues), convenience (easy real-time preparation), and numerous advantages such as cost-effectiveness and environmental friendliness. As a food disinfectant, ozone ensures safety and extends shelf life while preserving the nutritional, chemical, and physical properties of food. In daily life, ozone is commonly used for disinfecting and deodorizing indoor air, drinking water, and tableware. It is also widely applied in pollution control, effectively degrading harmful substances while providing decolorization, deodorization, and sterilization, thereby reducing the impact of pollutants on the environment and human health.
In addition to its use in environmental disinfection and sterilization, ozone can also be directly applied to treat various human diseases. Ozone has multiple applications in the healthcare field. For instance, in dental treatment, ozone can be used to rapidly kill bacteria, thereby avoiding the risk of allergic reactions or contraindications. Ozone is also employed in wound therapy to quickly alleviate pain and itching, as well as to prevent and control wound infections. Ozone therapy has demonstrated remarkable efficacy in the treatment of infectious wounds, circulatory system diseases, geriatric conditions, macular degeneration, viral diseases, rheumatism/arthritis, cancer, SARS, and AIDS.
In conclusion, although ozone bears an unappealing name, it is not a “bad guy.” As the Earth’s protective umbrella and a good friend of humanity, ozone possesses a charming aspect. Its unique chemical properties endow it with broad application prospects in agricultural pest control, industrial wastewater treatment, and the development of novel therapeutic approaches in the medical field.
References
[1] The controversial ozone. Institute of Physics and Chemistry, Chinese Academy of Sciences. 2015-03-04. [Retrieved: 2023-07-10] https://www.cas.cn/kx/kpwz/201503/t20150304_4317112.shtml
[2] agnieszka joanna brodowska, agnieszka nowak & krzysztof śmigielski(2017): ozone in the food industry: principles of ozone treatment, mechanisms of action,and applications. an overview, critical reviews in food science and nutrition, doi:10.1080/10408398.2017.1308313
[3] elvis, a.m. ekta, j.s.ozone therapy: a clinical review(2011) journal of natural science, biology and medicine, 2 (1), pp. 66 – 70,doi: 10.4103/0976-9668.82319
Source: Da Cheng Xiao e
Edited by: Jojani
Shangguan author: Shanghai Environment