求翻译：Fourth, the photocatalyst: photocatalytic decomposition can easily mold, mildew objects to solve the problem. While strong decomposition of ozone source to speed up organic matter, decomposition of toxic gases, improve air cleaning efficiency. Formaldehyde, acetaldehyde, formic acid, phenol, nicotine and other differences in the air is the main source of odor, such photocatalytic decomposition of organic matter can be better. Photocatalyst need professional maintenance more store construction, the general price of 300-500 dollars.是什么意思？

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