Fate Of Ozone Research Articles

Impact of Enhanced Ozone Deposition and Halogen Chemistry on Tropospheric Ozone over the Northern Hemisphere

Fate of ozone in marine environments has been receiving increased attention due to the tightening of ambient air quality standards. The role of deposition and halogen chemistry is examined through incorporation of an enhanced ozone deposition algorithm and inclusion of halogen chemistry in a comprehensive atmospheric modeling system. The enhanced ozone deposition treatment accounts for the interaction of iodide in seawater with ozone and increases deposition velocities by 1 order of magnitude. Halogen chemistry includes detailed chemical reactions of organic and inorganic bromine and iodine species. Two different simulations are completed with the halogen chemistry: without and with photochemical reactions of higher iodine oxides. Enhanced deposition reduces mean summer-time surface ozone by ∼3% over marine regions in the Northern Hemisphere. Halogen chemistry without the photochemical reactions of higher iodine oxides reduces surface ozone by ∼15% whereas simulations with the photochemical reactions of higher iodine oxides indicate ozone reductions of ∼48%. The model without these processes overpredicts ozone compared to observations whereas the inclusion of these processes improves predictions. The inclusion of photochemical reactions for higher iodine oxides leads to ozone predictions that are lower than observations, underscoring the need for further refinement of the halogen emissions and chemistry scheme in the model.

Uptake and fate of ozone in the respiratory tract

Ozone (O 3) is a ubiquitous pollutant with an array of established effects following acute and chronic exposure. Absorption of O 3 occurs in all regions of the respiratory tract, but injury to the pulmonary region appears to be of greatest concern because of the susceptibility of this region to the development of chronic disease. Processes that affect the uptake and transport of O 3 and available dosimetry models are briefly reviewed prior to discussing recent experimental dosimetry data in laboratory animals and humans. Dosimetry model predictions are compared with experimental data, and an example is provided that illustrates the potential for such models to contribute to our understanding of toxicological results.