Indoor secondary organic aerosols formation from ozonolysis of monoterpene: An example of D-limonene with ammonia and potential impacts on pulmonary inflammations

Monoterpene is one class of biogenic volatile organic compounds (BVOCs) which widely presents in household cleaning products and air fresheners. It plays reactive role in secondary organic aerosols (SOAs) formation with ozone (O₃) in indoor environments. Such ozonolysis can be influenced by the presence of gaseous pollutants such as ammonia (NH₃). This study focuses on investigations of ozone-initiated formation of indoor SOAs with D-limonene, one of the most abundant indoor monoterpenes, in a large environmental chamber. The maximum total particle number concentration from the ozonolysis in the presence of NH₃ was 60% higher than that in the absence of NH₃. Both of the nuclei coagulation and condensation involve in the SOAs growth. The potential risks of pulmonary injury for the exposure to the secondary particles formed were presented with the indexes of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-10 (IL-10) expression levels in bronchoalveolar lavage fluid (BALF) upon intratracheal instillation in mice lung for 6 and 12 h. The results indicated that there was 22–39% stronger pulmonary inflammatory effect on the particles generated with NH₃. This is a pilot study which demonstrates the toxicities of the indoor SOAs formed from the ozonolysis of a monoterpene.