In what scenario can the concentration of formaldehyde be particularly high?

The concentration of formaldehyde is particularly high in small or contained spaces due to limited air circulation and a higher likelihood of accumulation of indoor pollutants. When formaldehyde-based products, such as certain adhesives, building materials, and furniture, are present in these enclosed environments, the confined nature of the space can prevent the dispersal of fumes and result in elevated levels of this volatile organic compound (VOC). In addition, factors like temperature can exacerbate this buildup, as warmer environments tend to increase the emission rates of formaldehyde from materials.

While outdoor environments typically have a significantly lower concentration of indoor pollutants due to dilution, strong ventilation effectively reduces indoor pollutant levels by allowing for the exchange of indoor air with fresher outdoor air. Areas with high humidity can impact the behavior of formaldehyde but do not inherently lead to higher concentrations, as humidity levels can influence how the compound interacts with other materials and compounds in the air. Hence, small or contained spaces are where you're more likely to encounter elevated formaldehyde levels.