Limonene, commonly known as a lemon essential oil. It is often used to make citrus flavoring agents, and is one of the important chemical ingredients of many air fresheners, body sprays and other fragrances. Limonene itself is not terrible because the chemical is not harmful to the human body. It can be a big hazard. In fact, it can be used as a flavoring agent in foods. However, once limonene is sprayed into the air, it changes quickly. Studies have shown that when limonene is exposed to ubiquitous air, When in ozone, two limonene molecules form a single-molecule compound, methanol. When a large amount of limonene in a room is converted into methanol, the effect will be very different. From this we can infer:. ['The use of air fresheners may be harmful to us.', 'imonene is harmful to humans when used as a flavoring agent in food.', 'f a high methanol concentration is measured in the room, it means that too much fragrance is used.', 'n life, we should try to avoid using items containing limonene.']