Most laboratories contain a wide variety of chemicals that are used in instruction. These chemical substances can pose a number of potential IAQ-related problems when released into the school environment. The materials can become airborne by evaporation (at room temperature or at elevated temperatures by the addition of heat), by the generation of dust particles, and by release of gases, aerosols, and fumes by combustion and other chemical reactions. The potential health effects associated with laboratory chemicals range from noxious and irritating odors to serious acute respiratory effects and chronic disease or injury.

It is not feasible to discuss, or even list, all of the chemicals that may be found in school laboratories. School systems should use the least hazardous chemicals whenever possible and eliminate carcinogenic, highly toxic, and highly reactive chemicals from all laboratories unless there is some overriding educational benefit. A properly completed Material Safety Data Sheet (MSDS) will note if the chemical has been listed as a carcinogen by any national or international authority. The MSDS will also provide numerical (0, 1, 2, 3, or 4) ratings for health, flammability, and reactivity according to the National Fire Protection Association’s (NFPA) Standard 704. Ratings of 3 or 4 in any of these categories should be considered "highly" hazardous.

Additional substances that may be found in laboratories are asbestos, pesticides, and radiological materials. Asbestos was routinely used as an insulating material in some laboratory hoods and instrumentation and was bound to the center of wire gauze squares (typically used to support beakers on a ring stand when heating with a burner). Pesticides may be used in greenhouses, and some advanced laboratories may use small quantities of certain radioisotopes.

Biological organisms are often overlooked as sources of air contaminants. Many science programs are becoming quite sophisticated in their biological sciences curricula. Some advanced courses involve extensive experiments in microbiology that can introduce a variety of plants (flowers, mushrooms, etc.) and microbial organisms (e.g., fungi) into the school. Some of these plants may be outright toxic, while others may produce allergenic spores which can become airborne. Likewise, pathogenic and non-pathogenic microbiological organisms may be cultured, intentionally or unintentionally, in the laboratory and spread to other parts of the school facility if proper procedures are not used.

In response to students’ interest in animals, it is not uncommon to find environmental science classrooms that have numerous cages, aquaria, and terraria housing many mammals, fish, reptiles, and other forms of animal life. Great care must be taken to ensure that the animals and their cages, bedding, etc. do not become reservoirs of disease-carrying parasites and infectious agents. Also, a wide variety of animal hair and dander may cause allergic reactions (respiratory and skin) in teachers and students. Insect parts may also cause allergic reactions.

It is recommended that school laboratories use and house only animals that have been obtained from a scientific supply house. All wild animals should be excluded from schools.