Simon

Just like you said, there are various houseplants that can keep the air in our homes clean from pollutants and various harmful gases as well as balance indoor humidity.  I can't tell you which plant is the best, but here are several plants that you can use to clean the air in your household:     First up is the Spider plant, also known as chlorophytum comosum (as seen in the picture above). This plant is great at removing poisonous gases in your home, but be prepared that it can grow very rapidly. If you have cats they will love this plant as it - just like ordinary grass - contains folic acid, a vitamin which is essential to a cat’s well-being.     Another plant is the exotic-looking Boston fern (Nephrolepsis exaltata bostoniensis), which can also act as a natural humidifier.     The Golden Pothos (Epipremnum aureum), also known as Devil’s ivy or silver vine, is sometimes considered as weed due to its rather invasive characteristics. But the plant is very efficient when it comes to removing indoor pollutants. Just note that the plant is toxic to both children and pets.     A popular plant to remove indoor toxins is the Areca Palm (Chrysalidocarpus lutescens), best known for its humidifying effects. It's a rather sensitive plant that grows slowly and needs year-round care.     The Aloe Vera (Aloe barbadensis) plant is one of my favourites. Thanks to its many medicinal properties it's a plant that is used in many skin care products, but it can also filter various gas emissions in your home.

You have nothing to worry about. These energy efficient light bulbs, or CFLs as they are also often called, are completely safe.
 
The chemical you are referring to is mercury. Its true that mercury is a dangerous chemical, but the amount of mercury in a CFL is only 4 milligrams. This can be compared to the 500 milligrams that are inside every old-style thermometer that you put in either of your orifice. Here's another example to put things into perspective: a can of tuna, sadly, contains as much mercury as a CFL.
 
That said, its important that you don't buy the cheapest brand and that you recycle your broken CFLs.
 
Energy Star says this (pdf) about CFLs:
 
"CFLs contain a very small amount of mercury sealed within the glass tubing – an average of 4 milligrams (mg). By comparison, older thermometers contain about 500 milligrams of mercury – an amount equal to the mercury in  125 CFLs. Mercury is an essential part of CFLs; it allows the bulb to be an efficient light source. No mercury is  released when the bulbs are intact (not broken) or in use.   Most makers of light bulbs have reduced mercury in their fluorescent lighting products. Thanks to technology  advances and a commitment from members of the National Electrical Manufacturers Association, the average  mercury content in CFLs has dropped at least 20 percent or more in the past several years. Some manufacturers  have even made further reductions, dropping mercury content to 1 mg per light bulb."   So in conclusion: CFLs are safe. Switching from traditional light bulbs to CFLs (or LEDs) is an effective way to save money and electricity.