Uptaking Ozone by

Lung

Wenyan YuApril 24, 2003

Ozone Impacts on Your Body

Ozone, the main ingredient of smog, presents a serious air quality problem in many parts of the United States. Even at low levels, ozone can cause a number of respiratory effects.

Ozone can irritate your respiratory system:

. Causing you start to coughing, feel an irritation in your throat, and experience an uncomfortable sensation in your chest. Reducing lung function and make it more difficult for you to breathe as deeply and vigorously as you normally would. It makes people more sensitive to allergens, which are the most common triggers for asthma attacks.

Ozone can inflame and damage cells that line your lungs. Within a few days, the damaged cells are replaced and the old cells are shed—much in the way your skin peels after a sunburn. But, long period of lung exposure to ozone will cause permanent lung damage. Repeated short-term ozone damage to children’s developing lungs may lead to reduced lung function in adulthood. In adults, ozone exposure may accelerate the natural decline in lung function that occurs as part of the normal aging process.

A healthy lung air

way

Inflamed lung air

way

Lung Structure and How lung Uptake

Inhaled Gases

Lung Structure

Upper AirwaysFrom nose & lips --- Larynx(throat)

Conducting AirwaysA branched-tube network, From trachea --- terminal bronchioles

Respiration ZoneAll the alveolus & airspaces

Which Part of the Lung will uptake the Ozone??

Upper Airway: In the nose, the convoluted well-perfused surface of nasal turbinate with its large specific surface area of 8 cm2/ml provides an efficient site for absorption of soluble gases.

Conducting Airways: A highly reactive gas of only moderate solubility, can reach the tracheobronchial tree, where it reacts with the protective mucous layer and eventually damages underlying tissue in the small bronchioles.

Respiration Zone: A gas that has limited aqueous activity but is highly reactive with hemoglobin is able to penetrate further to the respiratory zone and diffuse to the pulmonary circulation in quantity.

O3

SO2

CO

Fundamentals of Mass Transport

• How to calculated the accumulation rate of the inhaled pollutant gas in the lung?

MVt

M

dt

dM Diffusion Rate <1>

+ Chemical Reaction Rate with the Tissue Layer <2>

y

MvMV

Diffusion Rate=

<3>

<1>2

22

y

MDMD xx

<3>

<2> Chemical Reaction Rate with Tissue Layer=

Consider Fick’s First Law for Diffusion:

121 )()/( xmxxxxxx

x SPkPPSlDdZ

dCSD

So we can express the accumulation Rate of Pollutant in Lung:

12

2

xmxx SPky

MD

y

Mv

t

M

Using Ideal Gas Law ： RTP and

AlVM

xmxxxxx Pka

y

AP

RT

D

y

AP

RT

v

t

p

RT

A

2

2 )()(

So we get:

How to Resolve the equation:

Some variables we need to deal with in the equation:

1. mxk It can be estimated by the stationary barrier eq, it should come from experiments, and it represents the character of the absorption film on the tissue layer.

2. v Respiratory flow speed: according to the character of breathing, we can suppose V varied with time in sinusoidal fashion.

3. A: cross-section available for the flow a: perimeter available for gas absorption

Then we can use numerical methods to resolve this equation:

xmxxxxx Pka

y

AP

RT

D

y

AP

RT

v

t

p

RT

A

2

2 )()(

Now, we know the mxk , which can be got from experimental results;

We also know the flow velocity which can be represented in sinusoidal fashion, but we still need to know the form of ‘A’ and ‘a’.

Conducting Airway:

This pic states that as the airway generation increase, there will be an exponential increasing in both ‘A’ and ‘a’. So, we can suppose that A=A.exp(cy), a=a.exp(dy), both c and d are parameters which can be deduced from experiments.

Thus we got all the variables and their relationships with the coordinate ‘y’ and time ‘t’, so the differential eq can be resolved by using numerical methods.

If we settle the time(it means that the flow speed doesn't change), we can get approximately the plot showing the relationship between Ozone concentration and the longitudinal distance y:

0

0. 5

1

1. 5

2

2. 5

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19l ongi tudi nal di stance y

concentration of

Ozone

From trachea to bronchioles