A Monte-Carlo Simulation of the Ozone Attainment Process

A Monte-Carlo simulation of the approach to attainment of the National Ambient Air Quality Standard for ozone has been performed for the California Bay Area Air Quality Management District. Four compliance tests together with different design values are used in the simulation. The results show that the present compliance test requiring a zero-percent chance of violation and the design value represented by the fourth highest value in three years makes both the standard and the control requirement much more stringent than generally assumed. In fact, to attain the standard on a long-term basis would require annual means and annual second-highest values that are close to those of the rural background ozone. The simulation also shows that by taking into account the fluctuation of ozone concentrations in the compliance test, such as a t test, and by using a design value consistent with the test, a standard defined in terms of the three-year mean of the annual second-highest values not only is more consistent with the currently- perceived stringency of the present standard, but may also be attainable with a more reasonable control requirement.     

Charcoal burning as a source of polyaromatic hydrocarbons in waterpipe smoking

Polyaromatic hydrocarbons (PAH) content from seven commercial waterpipe charcoals were determined during the smoking process to estimate how much PAHs would not be trapped by the water trap and could reach the lungs of the smokers. Naphthalene, 2-methylnaphthalene, acenaphthylene, acenaphthene, phenanthrene and fluoranthene were the most abundant PAH compounds produced during smoking. Naphthalene was the highest in all of the smoke contents and levels of 5 to 405 μg/15 minutes could be inhaled by the smoker. The amounts of PAHs produced during the smoking events in absence of tobacco varied greatly among different brands of charcoal. The amount and composition of the emitted PAH were not related to the amount and composition of the original chemicals in the charcoal prior to burning. Our findings suggest that public health agencies should regulate smoked charcoal products alongside tobacco.     

Ambient air concentrations exceeded health-based standards for fine particulate matter and benzene during the Deepwater Horizon oil spill

The Deepwater Horizon oil spill is considered one of the largest marine oil spills in the history of the United States. Air emissions associated with the oil spill caused concern among residents of Southeast Louisiana. The purpose of this study was to assess ambient concentrations of benzene (n=3,887) and fine particulate matter (n=102,682) during the oil spill and to evaluate potential exposure disparities in the region. Benzene and fine particulate matter (PM2.5) concentrations in the targeted parishes were generally higher following the oil spill, as expected. Benzene concentrations reached 2 to 19 times higher than background, and daily exceedances of PM2.5 were 10 to 45 times higher than background. Both benzene and PM2.5 concentrations were considered high enough to exceed public health criteria, with measurable exposure disparities in the coastal areas closer to the spill and clean-up activities. These findings raise questions about public disclosure of environmental health risks associated with the oil spill. The findings also provide a science-based rationale for establishing health-based action levels in future disasters.

Implications: Benzene and particulate matter monitoring during the Deepwater Horizon oil spill revealed that ambient air quality was a likely threat to public health and that residents in coastal Louisiana experienced significantly greater exposures than urban residents. Threshold air pollution levels established for the oil spill apparently were not used as a basis for informing the public about these potential health impacts. Also, despite carrying out the most comprehensive air monitoring ever conducted in the region, none of the agencies involved provided integrated analysis of the data or conclusive statements about public health risk. Better information about real-time risk is needed in future environmental disasters.