The effect of nitrogen dioxide on particle formation during ozonolysis of two abundant monoterpenes indoors

• Published in: Atmospheric environment (1994) Vol. 40; no. 6; pp. 1030 - 1042
• Main Authors: Nøjgaard, Jacob Klenø, Bilde, Merete, Stenby, Charlotte, Nielsen, Ole John, Wolkoff, Peder
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2006; Elsevier Science
• Subjects: Applied sciences; Atmospheric pollution; d-Limonene; Exact sciences and technology; Indoor pollution and occupational exposure; Nitrogen dioxide; Ozone; Pollution; Secondary organic aerosols; α-Pinene; Ozone; d-Limonene; Secondary organic aerosols; Nitrogen dioxide; α-Pinene; Ozonolysis; 1,8-p-Menthadiene; Hydrocarbon; Pollutant formation; Secondary pollutant; Volatile organic compound; Modeling; Chemical reaction kinetics; Terpene; Chemical reaction; Aerosols; Indoor pollution; Pinene; Organic compounds
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/j.atmosenv.2005.11.029

The effect of the nitrogen dioxide (NO 2) concentration on particle formation during ozonolysis of two abundant monoterpenes indoors, α-pinene and d-limonene, was studied in dry air in 1000 l Tedlar bags at 21±2 °C and ambient pressure. Particle size distributions were measured during 1 h after the reaction was initiated. In mixtures of 50 parts per billion volume (ppbv) of monoterpene and 50 ppbv of ozone (O 3), d-limonene produced about five times as many particles (10–350 nm) as α-pinene after 60 min. The presence of NO 2 introduced an additional loss term for O 3, resulting in formation of the nitrate radical. This affected particle formation, since the nucleation potential of NO 3 is much lower than O 3. Modeling showed that the observed decrease in particle concentration from d-limonene/O 3/NO 2 mixtures was likely to be ascribed to the O 3/NO 2 reaction at NO 2 concentrations <150 ppb, above which unknown mechanisms additionally reduced the particle formation. In similar experiments with α-pinene, the particle concentration and volume were substantially reduced in the presence of NO 2, e.g. 162 ppbv NO 2 reduced the particle number concentration by a factor of 10. In addition, the detection of particle formation was delayed as the NO 2 concentration increased, but the additional loss of O 3 in the O 3/NO 2 reaction could not explain the observation. The particle mode progressively increased with the NO 2 concentration for both monoterpenes. Oxidation of d-limonene may be highly relevant for new particle formation in indoor air, whereas ozonolysis products of α-pinene seem less likely to nucleate in indoor environments.