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Tropospheric Ozone

Presented by:

Prabesh Ghimire

BPH 3rd year

Valley College of Technical Sciences

A ground level ozone

Applied EnvironmentEnvironmental Pollution

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Tropospheric Ozone

y Troposphere:- the lowest portion of earths atmosphere.

y The troposphere extends from the surface of the earth tobetween 10 and 18 kilometers above the surface of the

earth.y Ozone is a naturally occurring gas found in the

troposphere ( & other parts of the atmosphere).

y Concentrations of ozone are not uniform in the

troposphere. (i.e. there are large diurnal and seasonalchanges in the concentrations of O3 in the loweratmosphere)

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Sources of Tropospheric Ozone

y Natural Sources

lighting during thunderstorms

downward mixing of O3 from the upper layers of the

atmosphere

y Anthropogenic Sources

through photochemical reactions that are driven by sunlight.

Note: Ozone is not emitted directly from a tailpipe or asmokestack; rather it is formed through reactions with volatileorganic compounds (VOC) and oxides of nitrogen (NOx).

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Tropospheric Ozone as pollutant

y Tropospheric ozone is formed by the interaction ofsunlight, particularly ultraviolet light, withhydrocarbons and nitrogen oxides (emitted by

automobiles, gasoline vapors, fossil fuel powerplants, refineries, & other industries)

y At abnormally high concentrations brought about byhuman activities (largely incomplete combustion of

fossil fuels, such as gasoline, diesel, etc.), it is apollutant, and a constituent of smog.

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Tropospheric Ozone as pollutant

y Tropospheric ozone is a greenhouse gas and initiatesthe chemical removal of methane and other

hydrocarbons from the atmosphere.y Ground-level ozone, though less concentrated than

ozone aloft (higher atmosphere), is more of aproblem because of its pollutant nature.

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Human Health Effects

y Irritation of the respiratory system causing coughing, throat irritation, and/or an uncomfortable

sensation in the chest.

y

Reduced lung function.y Breathing may become more rapid and more shallow

than normal

y Aggravation of asthma. (ozone makes people more

sensitive to allergens, which in turn trigger asthmaattacks)

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Human Effects

y Increased susceptibility to respiratory infections.

y Shortness of breath, dry cough or pain when taking adeep breath, tightness of the chest, wheezing, and

sometimes even nausea are common responses toozone.

y Inflammation and damage to the lining of the lungs.Within a few days, the damaged cells are shed and

replaced much like the skin peels after a sunburn.y It can worsen heart disease, bronchitis, and

emphysema.

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Human Effects

y It effects the human immune system, making it less reactive towardsbacteria and viruses and more responsive to allergens (which just sohappen to be highest when ozone levels peak in the summer months)(USEPA, 2009)

y

It affects the nervous system, causing alterations in circadian rhythmsand even perhaps contributing to the destruction of the substantianigra in Parkinson's disease through its oxidative effects (USEPA,2009).

y Other effects eye irritation

chest pain

coughing

Headaches

chest congestion and discomfort

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Effects in plants

y High concentrations of ozone cause plants to closetheir stomata. This slows down photosynthesis andplant growth.

y Ozone may also enter the plants through the stomataand directly damage internal cells.

y Rubber, textile dyes, fibers, and certain paints maybe weakened or damaged by exposure to ozone.

y Plants weakened by ozone may be more susceptibleto pests, disease, and drought.

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Thank

You!!!