Volatile organic compounds concentrations and sources inside new air-conditioned bus

The distributing profile and concentration level inside new air-conditioned buses with 53 seats have been determined using the method of thermal desorption-capillary GC/MS under vehicle static conditions. Compounds were identified from their mass spectral data by using US National Institute of Standards and Technology (NIST02). The total numbers of identified components were 33 inside buses, including alkenes (15, 45.4%), aromatic compounds (9, 27.3%), alcohols (4, 12.1%), ketones (3, 9.1%) and esters (2, 6.1%), especially in the range of C₆-C₁₀. The top 5 compounds measured inside buses were decane (8.01 mg/m³), 3-methylhexane (7.10 mg/m³), heptane (5.10 mg/m³), isoheptane (4.20 mg/m³) and 1-Methyl-3-ethylbenzene (3.56 mg/m³), and total volatile organic compounds (TVOC) ≥ 52.5 mg/m³. The main sources of in-vehicle hydrocarbons and aromatic compounds comes from cabin components and interior trim materials (e.g., sealants, carpets, adhesives, paints, leather, plastics, PU foam and PE foam) that may retain certain VOCs during manufacturing, and/or emit these compounds over an extended period of time from off-gassing, aging-related breakdown products, heating/cooling and so on.