What colorless gas can lead to contact dermatitis and discomfort in indoor environments?

Formaldehyde is a colorless gas known for its potential to cause allergic reactions, including contact dermatitis and discomfort, particularly in indoor environments. This compound is commonly found in many building materials, household products, and furnishings. When these materials off-gas formaldehyde, it can accumulate in indoor air, especially in spaces with poor ventilation.

Individuals exposed to formaldehyde can experience various symptoms, including skin irritation and respiratory issues. The chemical's classification as a volatile organic compound (VOC) further underscores its capacity to contribute to indoor air pollution and discomfort. Hence, formaldehyde stands out as the correct answer in this context because of its established connection to health problems linked to prolonged exposure in enclosed spaces.