|If we limit the amount of useage of either cargo
trucks or passenger cars, which of these two
would most decrease the amount of air pollution
|Question Date: 1999-01-25|
In Guadelupe, the air pollution is not the same as
in Los Angeles. The air pollution in your town is
mostly caused by dust and dirt from the farm
fields. Limiting cars or trucks would do little
to help. Changing how fields are plowed can help.
One thing that can be done is to spray water on
the field to keep the amount of dust down.
Your question is interesting.Like most science
problems, it has a big math component. We need to
know two things, how many cars (vs. trucks) are
there, and how much does each pollute. I don't
know the answer to part 1, but you could either
ask a local DMV office or do your own count. As
you probably know, vehicles in California have to
pass smog tests (more on this at the following web
This helps provide the information for part 2.
Check out http://www.smogcheck.ca.gov/asm1198.htm.
They have values for average emissions for
different weight vehicles. If we look at one type
of polution, hydrocarbons (unburned fuel that goes
out the tailpipe), and we look at vehicles made in
1993 or later, We see that, on average, trucks put
out twice as much as cars. So what percent of the
vehicles on the road would have to be trucks
before getting rid of trucks would help more than
getting rid of cars?
Notice that I made
some assumptions in deciding which numbers to use.
What if cars were usually newer than trucks?
What if I were more interested in lowering CO
For an overview of car pollution
problems and some solutions,
Vehicles which burn gas produce one type of
pollutant and vehicles which burn diesel produce
another type of pollutant. Please read about gas
burning vehicle pollution in earlier questions.
Both are not good.
Diesel is a more
efficient fuel source, which means that per amount
of diesel pumped into a diesel engine more of it
burns than the same amount of gas. The way a
combustion engine works is by pumping in some
combustible fuel (gas or diesel), burning the
fuel, the energy released from the burning of the
fuel is used to move the engine's pistons up and
down, which makes the wheels of the vehicle go
round and round (ha ha). So if you can burn all
of the fuel you pump into an engine you would be
at 100% efficiency. However, this does not
happen. So diesel engines are more efficient
which is always better for the environment, but
the product of combustion of diesel is a black
particulate matter that is harmful to the
environment and not good for humans and other
organisms. This is the black exhaust you see
pouring out of school buses and large trucks. So
it's a trade off; cars that burn gas as their
fuel aren't nearly as efficient as diesel
vehicles, but both put out bad pollutants--one is
invisible and the other is visible.
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