filter particles the size of bacteria from the air.

Kross

Senior Member
Korean
Hello, everyone

This is from an exercise.
Looking for mountain-fresh clean air in your own home? Clean-air filter units are so efficient that they can filter particles the size of bacteria from the air. (continued)

When I read the story for the first time, I found myself difficult to locate the object of the verb, filter. I couldn't notice the relationship between particles and the rest part, the size~ the air, at the moment.

To clearly display that particles is the object of the verb, filter, and the later part describes the object, I think that it would be better or correct to place a comma between particles and the later part like ~ particles, the size~.

We often witness this pattern. For example, Tom Jones, born in Boston, became famous as a historian. What do you think of my guess? What is the correct punctuation mark here? Is it just okay as it is(without a comma? All I have to do is improve my poor reading ability?
 
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  • owlman5

    Senior Member
    English-US
    I don't think you need the comma there, Kross, because "the size of bacteria" is essential, defining information.

    What kind of particles do the units filter? They filter particles the size of bacteria from the air.

    If "the size of bacteria" were nonessential information, then it would make sense to set the phrase off with commas.
     

    Qualityservant

    Senior Member
    English-USA
    To use or not use a comma depends on whether "the size of bacteria in the air" is required to convey the intended meaning. If there are particles of different sizes and you want to identify only those the size of bacteria in the air, then "the size of bacteria in the air" is required and no comma is used. If it is not necessary for clarification and wouldn't change the intended meaning without it, then the comma is required.
     

    entangledbank

    Senior Member
    English - South-East England
    A number of general words like 'size', 'shape', 'colour', 'length' can be used like this, directly without a comma: clouds the colour of mushrooms, a path the length of a football field, a dinosaur the height of a horse.
     

    Edinburgher

    Senior Member
    German/English bilingual
    Remember that "particles the size of bacteria" is a shortened form of a relative clause. It should be "particles that are the size of bacteria". Relative clauses of this kind are usually sub-categorized into either defining clauses (also known as a restrictive clauses) or non-defining (non-restrictive) clauses. General practice is to put commas around non-defining clauses but not around defining clauses.

    In this instance the particles in question are defined by their size being as small as bacteria, so no commas should be used, even when we take out the words "that are".
    This concept of "defining" is what Qualityservant called "required to convey the intended meaning". What's happening here is that from all possible particles we pick out the ones that are bacteria-sized.
     

    Kross

    Senior Member
    Korean
    Remember that "particles the size of bacteria" is a shortened form of a relative clause. It should be "particles that are the size of bacteria".
    As a English learner, I wonder if there is another way other than that are being inserted in the comma spot to clearly indicate that the noun, particles, is the only object of the verb, filter.
    For unskilled readers like me, it takes longer to figure out what the object is in the sentence. I had to closely look at the later part to see if they are included in the object group. Actually, I failed at the first attempt.
    That's because I was not sure about how far I had to include to the object group.

    This is my example sentence.
    Looking for mountain-fresh clean air in your own home? Clean-air filter units are so efficient that they can filter particles (the comma spot) the size of bacteria from the air. (continued)
     
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    Edinburgher

    Senior Member
    German/English bilingual
    (You have accidentally lost the word "from" between "bacteria" and "the air", although you have it correct in the thread title)

    Here is one easy way you can see that the object must be "particles":
    You have a set of four nouns which could possibly be the object: particles, size, bacteria, and air. The last two of these are part of prepositional phrases (from the air, of bacteria), and that eliminates them. It would have been possible to insert another preposition ("of") in your "comma spot" instead of "that are": "particles of the size of bacteria", and that then eliminates "size", and you now have only one candidate left ("particles") that can be your object.

    (It was a little naughty of you to call that position "comma spot" because, as discussed, you do not want to put a comma there)
     

    Kross

    Senior Member
    Korean
    I happened to find rules of comma usage on a web site. (source: http://grammar.ccc.commnet.edu/grammar/commas.htm) No. 8 is the one I wanted to apply to the spot in question here. (~ they can filter particles(,) the size of bacteria from the air.~)

    This is about the No. 8 rule.
    Use a comma to avoid confusion. This is often a matter of consistently applying rule #3.

    • For most the year is already finished.
    • For most, the year is already finished.
    • Outside the lawn was cluttered with hundreds of broken branches.
    • Outside, the lawn was cluttered with hundreds of broken branches.
    Is my question sentence is totally different from the No. 8 rule or its examples? Is mine not that confusing? I just wanted to seperate the particles part from the later part to avoid confusion or kindly help readers find the object of the verb, filter, with ease.
     
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    Edinburgher

    Senior Member
    German/English bilingual
    Yes, your context is not the same.

    Your rule 8 examples are to avoid confusion which might result from hasty parsing of the sentence.

    When you read "For most the year is already finished." you might (wrongly) understand this as "Because most of the year is already over",
    but "For most, the year is already finished." makes clear that we mean "Most people feel that the year is already over".

    "Outside the lawn was cluttered with hundreds of broken branches." can be misinterpreted as "The area that is not part of the lawn was cluttered",
    but "Outside, the lawn was cluttered with hundreds of broken branches." makes clearer that we mean "There is a lawn outside (that is, outside the house), and it was cluttered."

    In your filter example, there is no scope for that kind of confusion. The phrase "the size of bacteria" is something which adds information about the particles, and such a phrase either needs two commas (one before it and one after it), or zero commas.

    (a) They can filter particles, the size of bacteria, from the air.
    (b) They can filter particles the size of bacteria from the air.

    We generally use the zero-comma version (b) when the phrase defines what kind of particles we are talking about (this is the case here). We would use the two-comma version (a) if the phrase adds non-defining information about the particles. Sometimes it's difficult to decide whether a phrase is defining or non-defining. :( I'm pretty sure it's defining in your case, because it's telling us that the filters are so fine that can extract very very small particles; it's telling us what size of particles the filters can take out. It's not just saying the filters can take particles out, and adding something about their size as a merely incidental detail. That's why I think you need the zero-comma version here.
     
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