Sources and symptoms
As in many modern environments, there is a risk of exposure to harmful chemicals in the various school settings. We are well aware of the risks to health posed by accidentally ingesting or touching chemical products with our bare hands. Safety labels often bear the warning “Keep out of reach of children”, reminding us to store the products safely to prevent accidental ingestion or exposure. However, there are other ways in which school personnel and students can be exposed to chemical hazards — for example through breathing in harmful concentrations of chemicals released into the indoor air from materials or products that are indoor sources of chemical pollutants.
Liquids and gases
These chemicals are released in gaseous form by almost all synthetic solid materials or liquid products that are used to build, decorate, maintain, furnish, clean and sanitise indoor environments (including paints, plastics, cleaning products and fragrances, air fresheners, adhesives and solvents, particleboard furniture, carpets, vinyl flooring, vinyl wallpaper, electronic equipment, biocides and pesticides). These substances belong to a large group of chemicals known as volatile organic compounds (VOCs), which includes a sub-group of particular concern with respect to environment and health, known as semi-volatile organic compounds (SVOCs). In the indoor air, they may reach higher levels during activities such as daily cleaning or the occasional renovation of school buildings or interiors. This has been confirmed in numerous studies that have shown higher indoor concentrations of some chemicals compared to those in the outdoor air, suggesting that such pollutants have come mostly from inside the building.
Some (like formaldehyde and certain solvents) have a very pungent odour, while others may mimic natural odours such as pine or lemon (e.g. limonene). Some materials, including paints, new carpets and furniture, release VOCs slowly over time, from several weeks to several years, with higher peaks when they are delivered from the manufacturer or put into use for the first time. Others, such as cleaning products, release small amounts of chemicals every time they are used and even during storage. Indoor sources of VOCs include building materials and furnishings (e.g. carpets, insulation, paints, wood finishing products, furniture and floor coverings), cleaning products and air fresheners, office equipment, and the activities of building users (e.g. smoking, art activities, chemistry lab activities and the use of personal care products). Among the key indoor sources of SVOCs are pest control products, building and decorating materials made of or containing flexible plastics such as vinyl wallpaper or vinyl flooring, and furniture containing flame retardants. However, the same chemical may have different sources: phthalates, for example, may be emitted by plastic flooring, the fragrance used in air fresheners, or even from cosmetics.
Exposure and symptoms
Excessive concentrations of indoor chemicals in the air may cause generic symptoms such as headaches or nausea, or irritation including itchy eyes and sneezing. In sensitive people they may cause allergic reactions or asthma attacks. More recent research has also indicated the possibility of them having toxic health effects after years of exposure, even at low doses, particularly in the case of vulnerable groups such as children. Some SVOCs may alter the activity of hormones in humans and wildlife and are therefore known as endocrine disruptors. In order to avoid harmful concentrations of these pollutants in the indoor air, it is recommended to ensure adequate and regular ventilation and to choose materials and products that have very low emissions of chemicals or no emissions of substances known to be dangerous, based on ecological labelling. Learning to read such labels can also help avoid risks from other chemical hazards that exist in schools. Unlike biological pollutants, chemicals are also toxic to the environment, not only as a result of the environmental pressures they exert during their life cycle, but also because they contribute to outdoor VOCs emissions that play a role in ground-level ozone formation and, if the materials that emit them are inappropriately disposed of, may pollute water and soil. Learning how to choose and use safer consumer products and manage sources of indoor pollutants in buildings is therefore important both for sustainability and health.