Hello, everyone. In this video,
we will introduce the combustion related indoor pollutant, carbon monoxide.
Combustion is a chemical process where a substance reacts with oxygen to produce heat.
There are 2 types of combustion:
complete combustion, with sufficient oxygen for burning;
and an incomplete combustion, with lack of oxygen for burning.
The products from complete and incomplete combustion
are different, even for the same substance.
For example, for methane,
the product of complete combustion are carbon dioxide and water.
For incomplete combustion, only carbon monoxide is produced.
The pollutants from combustion can be gas or particles.
They usually come from incomplete combustion of fuels such as natural gas,
liquefied petroleum, gas, fuel oil,
kerosenes, wood or coal.
The common pollutants from combustion are list here: carbon monoxide, nitrogen dioxide,
particles, sulfur dioxide, unburned hydrocarbons, and aldehydes.
We will focus on carbon monoxide and then nitrogen dioxide in this course.
Carbon monoxide is formed from one carbon atom and one oxygen atom.
Normally, it is colorless, odorless, and tasteless.
It is soluble in alcohol and benzene,
but only slightly soluble in water.
Those are the indoor sources of carbon monoxide.
It is normally found where the fuel is being burned,
such as heaters and stoves.
Other sources of carbon monoxide can be found in
power plants and from the car exhaust fumes.
Carbon monoxide concentration in the air can be measured by electrochemical sensor.
Air first diffuse through the porous membrane.
Then electrochemical oxidation will occur.
In the process, carbon monoxide reacts with water to form carbon dioxide,
which release two electrons producing a signal.
Increasing carbon monoxide concentration in the environment will have
a worsening effect on human health.
When carbon monoxide concentration is low,
people may feel fatigue,
while those with heart disease may feel chest pain.
As carbon monoxide concentration increases,
people may also
experience the following symptoms: impaired vision and coordination, headaches,
dizziness, confusion and nausea.
But be careful, these symptoms are often mistaken as symptoms of flu.
Staying in an environment exposed to high carbon monoxide may cause death,
since carbon monoxide reacts with haemoglobin in our blood to form carboxyl-haemoglobin.
Then the ability of red blood cell to carry oxygen decreases significantly
as haemoglobin has more affinity to carbon monoxide than oxygen.
To maintain low level of carbon monoxide in an indoor environment,
we should supply enough oxygen when cooking or burning something.
An exhaust fan must be installed next to any cooking areas to exhaust the pollutants.
Regular maintenance and the cleaning of
combustion equipment is also important to avoid carbon monoxide leakage.
Importantly, an idling car in an
enclosed car parking area will also release carbon monoxide.
So it is better to prevent pollution by turning off the engine.
To conclude, we have introduced what combustion is,
and the sources of carbon monoxide.
Then we talked about measurement methods of carbon monoxide.
We also discussed the health effects of carbon monoxide.
Finally, we have suggested some methods to control carbon monoxide concentration indoors.