Secondary organic aerosols from ozone-initiated reactions with emissions from wood-based materials and a “green” paint

Abstract

This study examined the formation and growth of secondary organic aerosols (SOA) generated when ozone was added to a 1 m 3 glass chamber that contained either pine shelving, oriented strand board (OSB), beech boards, or beach boards painted with an “eco” paint. The experiments were conducted at close to real-world conditions; the chamber was ventilated at ∼0.5 air changes/h; the loadings (exposed surface of building materials to chamber volume) were in the range of 1–2.5 m 2 m −3; and the initial O 3 concentrations were between 15 and 40 ppb. Throughout each experiment particles were measured with both a condensation nuclei counter and an optical counter, while terpenes were measured before and after the ozone exposure period using sorbent tubes. The pine boards emitted primarily α-pinene and 3-carene and lesser amounts of 5 other terpenes; when O 3 was introduced, the particle counts increased dramatically; the mass concentration reached ∼15 μg m −3 at ∼20 ppb O 3, and ∼95 μg m −3 at ∼40 ppb O 3. The OSB emitted primarily limonene and α-pinene. Although the particle counts increased when O 3 was introduced, the increase was not as large as anticipated based on the terpene concentrations. The beech boards emitted negligible quantities of terpenes, and the introduction of O 3 resulted in almost no increase in the particle concentration. Beech boards painted with an “eco” paint emitted large amounts of limonene and lesser amounts of carvone; upon introduction of O 3 the particle counts increased sharply with the mass concentration reaching ∼20 μg m −3 at ∼15 ppb O 3 and ∼160 μg m −3 at ∼35 ppb O 3. These experiments demonstrate that the emission of terpenes and potential generation of SOA varies greatly among different types of wood and pressed wood materials. In the case of the pine boards and painted beech boards, the SOA concentrations generated at modest O 3 concentrations approach or exceed current guideline levels for PM 2.5 established by the US EPA and the World Health Organization.