Keep bathrooms well-ventilated when cleaning them. Image Source/ Getty Images

­Air fresheners and cleaning solutions freshen and sanitize our indoor habitats. However, a study by the University of California at Berkeley found that when used excessively or in a small, unventilated area, these products release toxic levels of pollutants. This comes from two main chemicals called ethylene-based glycol ethers and terpenes [source: Science Daily]. While the EPA regards the ethers as toxic by themselves, the non-toxic terpenes can react with ozone in the air to form a poisonous combination [source: ScienceDaily].

Air fresheners in particular are linked to many volatile organic compounds, such as nitrogen dioxide. Concentrations of this chemical are two to five times higher indoors than outdoors, which can cause cancer in some animals [source: EPA]. Some fresheners also contain paradichlorobenzene, the same chemical we discussed earlier with mothballs.

Cleaning your bathroom or spritzing air freshener shouldn't make you sick, but you must keep air circulating through the area as a precaution. Professional house cleaners should especially ensure that they aren't breathing harmful levels of these chemicals on the job [source: ScienceDaily].