Heterogeneous chemistry on mineral dust particles causes significant reductions in important tropospheric trace gases such as O3, OH, and HNO3 in dust-dominated regions such as the North African Tropical Atlantic region. We analyze the spatial and temporal modes of dust-induced heterogeneous ozone removal (∆HO3) using empirical orthogonal functions (EOFs) and principal components analysis. We u...

Ground level ozone concentrations ([O(3)]) typically show a direct linear relationship with surface air temperature. Three decades of California measurements provide evidence of a statistically significant change in the ozone-temperature slope (Δm(O3-T)) under extremely high temperatures (> 312 K). This Δm(O3-T) leads to a plateau or decrease in [O(3)], reflecting the diminished role of nitroge...

background: today, air pollution is one of the major problems in large cities including isfahan. methods: the objective of this study was to investigate the variations of ozone (o3), carbon monoxide (co), nitric oxide (no), nitrogen dioxide (no2), nitrogen oxides (nox), sulphur dioxide (so2), and particulate matter (pm10) concentrations in different months at three stations and also to explore ...

Sugar beet (Beta vulgaris cv. Loretta) and rape (Brassica napus cv. Licolly) plants were exposed under equal dose conditions in closed fumigation chambers under two different ozone (O3) pattern: Var130 (17:00–09:00 h: 40 μg O3 m −3; 09:00–17:00 h: 130μg O3 m−3) and Var220 (16:0012:00 h: 40 μg O3 m −3; 12:00–16:00 h: 220μg O3 m−3). Control plants were exposed under carbon filtered air conditions...

Besides oxygen, several other gases such as NO, CO, H2, H2S, Xe and O3 have come to age over the past few years. With regards to O3, its mechanisms of action in medicine have been clarified during the last two decades so that now a comprehensive framework for understanding and recommending ozone therapy in various pathologies is available. O3 used within the determined therapeutic window is abs...

An ozone exposure assessment study was conducted in a Southern California community. The Harvard ozone passive sampler was used to monitor cohorts of 22 and 18 subjects for 8 weeks during the spring and fall of 1994, respectively. Ozone exposure variables included 12-hr personal O3 measurements, stationary outdoor O3 measurements from a continuous UV photometer and from 12-hr Harvard active mon...

9 [1] We examine the photochemical processes governing the production of ozone in 10 smoke from large Siberian fires that formed in July 2006 using colocated O3 and 11 CO profiles as measured by the Tropospheric Emission Spectrometer as well as NO2 and 12 aerosol optical depths as measured by the Ozone Monitoring Instrument. The Real-Time 13 Air Quality Model (RAQMS) is used to explain the obse...

We use a Lagrangian chemical transport model with a Monte Carlo approach to determine impacts of kinetic rate uncertainties on simulated concentrations of ozone, NOy and OH in a high-altitude biomass burning plume and a low-level industrial pollution plume undergoing long-range transport. Uncertainties in kinetic rate constants yield 10–12 ppbv (5th to 95th percentile) uncertainty in the ozone ...

Numerous studies of ambient ozone (O3) in the Los Angeles (LA) area have found both increases and decreases in elevated O3 levels on weekends, depending on location and year. Since the mid-1990s, average daily maximum O3 levels have been higher on weekends than on weekdays throughout most of the area. We used the Comprehensive Air-Quality Model with extensions to investigate causes of weekday/w...

Ozone (O3) and hydrogen peroxide (H2O2) volume fractions were calculated using the Master Mechanism (MM) model, author S. Madronich (NCAR, Boulder, CO, USA). MM is an atmospheric “box” model program for calculating the time evolution of atmospheric composition from initial amounts of atmospheric gases under chosen or varying conditions using reaction rate data and other physicochemical paramete...