Indoor air pollution is much more common and can be more severe than outdoor pollution. The wind blows fresh new air. The rain cleans the air and plants of dust and pollutants, unfortunately that does not happen indoors. An exhaust fan is the main tool to maintain fresh air. The nutrients in fertilizer dissolve in water.
Water carries nutrients through the plant.
Unfortunately, common tap water may contain high levels of alkaline salts, sulphur or chlorine and may have a pH out of the acceptable 6 to 7 range. There is a wide range of products that help you eliminate these problems. Nutrients are very complex formulas and the amount of formulas available in the market is quite large. You have to choose which formula is best for the type of plant that you are growing. The best nutrients are the ones that are specific for a particular type of crop.