Controlling Ozone and Fine Particulates: Cost Benefit Analysis with Meteorological Variability

In this paper, we develop an integrated cost-benefit analysis framework for ozone and fine particulate control, accounting for variability and uncertainty. The framework includes air quality simulation, sensitivity analysis, stochastic multi-objective air quality management, and stochastic cost-benefit analysis. This paper has two major contributions. The first is the development of stochastic source-receptor (S-R) coefficient matrices for ozone and fine particulate matter using an advanced air quality simulation model (URM-1ATM) and an efficient sensitivity algorithm (DDM-3D). The second is a demonstration of this framework for alternative ozone and PM2.5 reduction policies. Alternative objectives of the stochastic air quality management model include optimization of the net social benefits and maximization of the reliability of satisfying certain air quality goals. We also examine the effect of accounting for distributional concerns.ambient air, ozone, particulate matter, risk management, public policy, cost-benefit analysis, variability and uncertainty, stochastic simulation, stochastic multi-objective programming, decisionmaking, National Ambient Air Quality Standards

Source-Receptor Relationships for Ozone and Fine Particulates in the Eastern United States

A key question in developing effective mitigation strategies for ozone and particulate matter is identifying which source regions contribute to concentrations in receptor regions. Using a direct approach with a regional, multiscale three-dimensional model, we derive multiple source-receptor matrices (S-Rs) to show inter- and intrastate impacts of emissions on both ozone and PM2.5 over the eastern United States. Our results show that local (in-state) emissions generally account for about 23% of both local ozone concentrations and PM2.5 concentrations, while neighboring states contribute much of the rest. The relative impact of each state on others varies dramatically between episodes. In reducing fine particulate concentrations, we find that reducing SO2 emissions can be 10 times as effective as reducing NOx emissions. SO2 reductions can lead to some increase in nitrates, but this is relatively small. NOx reductions, however, lead to both ozone reductions and some reduction in nitrate and sulfate particulate matter.source-receptor, ozone, particulate matter, sensitivity analysis, air quality simulation, National Ambient Air Quality Standards

Verification of a mathematical model for aerosol nitrate and nitric acid formation and its use for control measure evaluation

A mathematical model for the formation of atmospheric nitric acid and aerosol nitrate has been developed and employed to study the effect of emission controls. Based on a Lagrangian formulation of the atmospheric diffusion equation, the model computes nitric acid concentrations from a description of daytime photochemical reactions and night-time reactions involving NO_3 and N_2O_5. Ammonium nitrate formation is computed at a thermodynamic equilibrium between HNO_3 and NH_3, and heterogeneous reactions between HNO_3 and preexisting aerosol are considered. The accuracy of the air quality model's predictions is verified by comparison to O_3, NO_2, HNO_3, NH_3, aerosol nitrate and PAN measurements made for this purpose in California's South Coast Air Basin during the period of 30–31 August 1982. Examination of emission control alternatives shows that reduction in NO_x emissions yields a nearly proportional decrease in total inorganic nitrate levels (HNO_3 + aerosol nitrates). Reduction in NH_3 emissions suppresses aerosol nitrate formation, resulting in higher HNO_3 levels. Control of organic species emissions by the amounts expected in Los Angeles in future years causes a partial shift away from PAN formation toward greater production of HNO_3. Emission control strategies can be formulated that include a combination of controls on NO_x organic gases and NH_3 emissions that will achieve a greater reduction in HNO_3, aerosol nitrate and O_3 levels than a strategy predicated on control of only a single precursor species

Dry deposition of nitrogen containing species

Nitrogen oxides (NO_x) emissions and the oxidation products formed by photochemical interactions in the atmosphere are responsible for a significant fraction of both dry and wet acid deposition fluxes. In his paper a vertically-resolved, Lagrangian trajectory model is used to predict the diurnal variation of: NO, NO_2, NO_3, HONO, HONO_2, HO_2NO_2, RONO, RONO_2, RO_2NO_2, N_2O_5 and PAN over an urban airshed. Particular attention is given to the fate of nitric acid and its reaction with gaseous ammonia to form, aerosol phase, ammonium nitrate. A simple model for estimating the deposition fluxes of these species is also presented. A study of the fate of nitrogen oxides emissions, in the South Coast Air Basin of southern California, is used to illustrate the procedures

Ozone Formation Potential of Organic Compounds in the Eastern United States: A Comparison of Episodes, Inventories, and Domains

Direct sensitivity analysis is applied for 3-D assessment of ozone reactivity (or ozone formation potential) in the Eastern United States. A detailed chemical mechanism (SAPRC-99) is implemented in a multiscale air quality model to calculate the reactivity of 32 explicit and 9 lumped compounds. Simulations are carried out for two different episodes and two different emission scenarios. While absolute reactivities of VOCs show a great deal of spatial variability, relative reactivities (normalized to the reactivity of a base mixture) produce a significantly more homogeneous field. Three types of domain-wide relative reactivity metrics are formed for 1-h and 8-h averaging intervals. In general, ozone reactivity metrics (with the exception of those based on daily peak ozone) are fairly robust and consistent between different episodes or emission scenarios. The 3-D metrics also show fairly similar rankings for VOC reactivity when compared to the box model scales. However, the 3-D metrics have a noticeably narrower range for species reactivities, as they result in lower reactivity for some of the more reactive, radical-producing VOCs (especially aldehydes). As expected, episodes and emission scenarios with less radical availability have higher absolute reactivities for all species and higher relative reactivities for the more radical-producing species. Finally, comparing the results with those from a different domain (central California) shows that relative reactivity metrics are comparable over these two significantly different domains

The dynamics of nitric acid production and the fate of nitrogen oxides

A mathematical model is used to study the fate of nitrogen oxides (NO_x) emissions and the reactions responsible for the formation of nitric acid (HNO_3). Model results indicate that the majority of the NO_x inserted into an air parcel in the Los Angeles basin is removed by dry deposition at the ground during the first 24 h of travel, and that HNO_3 is the largest single contributor to this deposition flux. A significant amount of the nitric acid is produced at night by N_2O_5 hydrolysis. Perturbation of the N_2O_5 hydrolysis rate constant within the chemical mechanism results in redistribution of the pathway by which HNO_3 is formed, but does not greatly affect the total amount of HNO_3 produced. Inclusion of NO_3-aerosol and N_2O_5-aerosol reactions does not affect the system greatly at collision efficiencies, α, of 0.001, but at α = 0.1 or α = 1.0, a great deal of nitric acid could be produced by heterogeneous chemical processes. Ability to account for the observed nitrate radical (NO_3) concentrations in the atmosphere provides a key test of the air quality modeling procedure. Predicted NO_3 concentrations compare well with those measured by Platt et al. (Geophys. Res. Lett.7, 89–92, 1980). Analysis shows that transport, deposition and emissions, as well as chemistry, are important in explaining the behavior of NO_3 in the atmosphere

Carbon Free Boston: Technical Summary

Part of a series of reports that includes: Carbon Free Boston: Summary Report; Carbon Free Boston: Social Equity Report; Carbon Free Boston: Buildings Technical Report; Carbon Free Boston: Transportation Technical Report; Carbon Free Boston: Waste Technical Report; Carbon Free Boston: Energy Technical Report; Carbon Free Boston: Offsets Technical Report; Available at http://sites.bu.edu/cfb/OVERVIEW: This technical summary is intended to argument the rest of the Carbon Free Boston technical reports that seek to achieve this goal of deep mitigation. This document provides below: a rationale for carbon neutrality, a high level description of Carbon Free Boston’s analytical approach; a summary of crosssector strategies; a high level analysis of air quality impacts; and, a brief analysis of off-road and street light emissions.Published versio