Ozone (O₃)

Ozone (O₃):

Ozone/ or trioxygen, is an inorganic molecule with the chemical formula O₃. It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope O₂, breaking down in the lower atmosphere to O₂ (dioxygen). Ozone is formed from dioxygen by the action of ultraviolet light (UV) and electrical discharges within the Earth’s atmosphere. It is present in very low concentrations throughout the latter, with its highest concentration high in the ozone layer of the stratosphere, which absorbs most of the Sun’s ultraviolet (UV) radiation.

Ozone’s odour is reminiscent of chlorine, and detectable by many people at concentrations of as little as 0.1 ppm in air. Ozone’s O₃ structure was determined in 1865. The molecule was later proven to have a bent structure and to be diamagnetic. In standard conditions, ozone is a pale blue gas that condenses at progressively cryogenic temperatures to a dark blue liquid and finally a violet-black solid. Ozone’s instability with regard to more common dioxygen is such that both concentrated gas and liquid ozone may decompose explosively at elevated temperatures or fast warming to the boiling point. It is therefore used commercially only in low concentrations.

Ozone is a powerful oxidant (far more so than dioxygen) and has many industrial and consumer applications related to oxidation. This same high oxidising potential, however, causes ozone to damage mucous and respiratory tissues in animals, and also tissues in plants, above concentrations of about 0.1 ppm. While this makes ozone a potent respiratory hazard and pollutant near ground level, a higher concentration in the ozone layer (from two to eight ppm) is beneficial, preventing damaging UV light from reaching the Earth’s surface.

Effects of O₃ on human health:

Ozone can cause the muscles in the airways to constrict, trapping air in the alveoli. This leads to wheezing and shortness of breath.

Ozone can:

1. Make it more difficult to breathe deeply and vigorously.
2. Cause shortness of breath, and pain when taking a deep breath.
3. Cause coughing and sore or scratchy throat.
4. Inflame and damage the airways.
5. Aggravate lung diseases such as asthma, emphysema, and chronic bronchitis.
6. Increase the frequency of asthma attacks.
7. Make the lungs more susceptible to infection.
8. Continue to damage the lungs even when the symptoms have disappeared.
9. Cause chronic obstructive pulmonary disease (COPD).

These effects have been found even in healthy people, but can be more serious in people with lung diseases such as asthma. They may lead to increased school absences, medication use, visits to doctors and emergency rooms, and hospital admissions.

Long-term exposure to ozone is linked to aggravation of asthma, and is likely to be one of many causes of asthma development. Long-term exposures to higher concentrations of ozone may also be linked to permanent lung damage, such as abnormal lung development in children.

Recent studies consistently report associations between short-term ozone exposures and total non-accidental mortality, which includes deaths from respiratory causes. Studies suggest that long-term exposure to ozone also may increase the risk of death from respiratory causes, but the evidence is not as strong as the evidence for short-term exposure.

Environmental effects of O₃:

Troposphere or ground level ozone is a harmful, photochemical oxidant that significantly contributes to the formation of smog. Troposphere ozone is regularly measured as an indicator of smog levels in the atmosphere. Scientific evidence also indicates that ground level ozone can have a detrimental impact on the environment.  This impact can lead to reductions in agricultural crop and commercial forest yields, reduced growth and survivability of tree seedlings, and increased plant susceptibility to disease, pests, and other environmental stresses (e.g. harsh weather). Other problems resulting from excessive ozone levels can include damage to the ecosystem including the retardation of plant growth and crop yields.

Interested Parties including Regulatory Authorities:

1. Persons affected by O3
2. Industries, Laboratories using/ Generating O3
3. Warehouses Containing Chemicals of O3
4. Motor Vehicles for personal and commercial uses
5. Private / Govt. Projects to control O3
6. Handling and transportation of chemical containing O3
7. Local Environmental Department/ Authorities
8. Local Government Authorities like Municipalities, City
9. Corporation etc.
10. Local Law Enforcing Agencies like Police, Magistrate and Regulatory Authorities etc.

Benefits of Monitoring:

By monitoring long-term contamination trends, every country establishes baseline contamination levels, making it possible for early identification of contamination events. Daily events and long term trends are captured and steps are taken reduce environmental emission/ pollution and enhance environmental performance of the society.