How do we use に気をつける vs を気をつける？


に気をつける is a much more popular expression, from what I see, compared to を気をつける.
But the latter is still not that rare.

Is there any significant difference between these two and something to be wary
of upon choosing to use either?




を気をつける is much rarer. The BCCWJ gives the following numbers:

[code]

    　に気を（つ・付） 1363 results
    には気を（つ・付）  181 results 
    　は気を（つ・付）  155 results
    　を気を（つ・付）   26 results
    
[/code]

giving

[code]

    に（は） 89.5%
    は　　　  9.0%
    を　　　  1.5%
    
[/code]

First of all, I think that this shows that に or は are much more common.
Moreover, I think that in most of the cases, you can replace を by に without
much trouble.

However, in examples such as

> その辺を気をつける
>
> ここのところを気をつける

に may be misinterpreted as a location marker, because the preceding word can
also describe a location, even if it used differently in these sentences. (The
に in ～に気をつける is rather the "direction" marker (used in a figurative sense).)

Also, を can be used as a last resort, because に（は） has been used already, as
in

> コバエ防止には、エサを気をつけています。




を気をつける is much rarer. The BCCWJ gives the following numbers:

[code]

    　に気を（つ・付） 1363 results
    には気を（つ・付）  181 results 
    　は気を（つ・付）  155 results
    　を気を（つ・付）   26 results
    
[/code]

giving

[code]

    に（は） 89.5%
    は　　　  9.0%
    を　　　  1.5%
    
[/code]

First of all, I think that this shows that に or は are much more common.
Moreover, I think that in most of the cases, you can replace を by に without
much trouble.

However, in examples such as

> その辺を気をつける
>
> ここのところを気をつける

に may be misinterpreted as a location marker, because the preceding word can
also describe a location, even if it used differently in these sentences. (The
に in ～に気をつける is rather the "direction" marker (used in a figurative sense).)

Also, を can be used as a last resort, because に（は） has been used already, as
in

> コバエ防止には、エサを気をつけています。

