Adjoint estimation of ozone climate penalties

An adjoint of a regional chemical transport model is used to calculate location-specific temperature influences (climate penalties) on two policy-relevant ozone metrics: concentrations in polluted regions (>65 ppb) and short-term mortality in Canada and the U.S. Temperature influences through changes in chemical reaction rates, atmospheric moisture content, and biogenic emissions exhibit significant spatial variability. In particular, high-NO x, polluted regions are prominently distinguished by substantial climate penalties (up to 6.2 ppb/K in major urban areas) as a result of large temperature influences through increased biogenic emissions and nonnegative water vapor sensitivities. Temperature influences on ozone mortality, when integrated across the domain, result in 369 excess deaths/K in Canada and the U.S. over a summer season - an impact comparable to a 5% change in anthropogenic NOx emissions. As such, we suggest that NOx control can be also regarded as a climate change adaptation strategy with regard to ozone air quality. Key Points Ozone climate penalties in North America show great spatial variability High-NOx regions are among locations with the largest climate penalties NOx control can be seen as a climate change adap

Attainment vs exposure: Ozone metric responses to source-specific NO x controls using adjoint sensitivity analysis

We establish linkages between sources of NOx emissions and two types of national ozone metrics in Canada and the U.S. using the adjoint of an air quality model. We define an attainment-based metric using probabilistic design values (PDVs) exceeding 65 ppb to represent polluted regions and define an exposure-based metric as the premature mortality count related to short-term ozone exposure, both in Canada and the U.S. Our results reveal differences in both temporally averaged and day-specific influences of NOx emission controls across source locations. We find NOx emission reductions in California and the eastern U.S. to be most effective for reducing attainment- and exposure-based metrics, amounting to a total reduction of 6500 ppb in PDVs and 613 deaths/season nationally from a 10% reduction in NOx emissions from those source locations. While source controls in the remainder of the western U.S. are beneficial at reducing nonattainment, these reductions are less influential on ozone mortality. We also find that while exposure-based metrics are sensitive to daily emission reductions, much of the reduction in PDVs arises from controlling emissions on only a fraction of simulation days. We further illustrate the dependency of adjoint estimates of emission influences on the choice of averaging period as a follow-up to previous work

Variability in ozone metrics with emission reductions and its application in health impact assessment

With advancing evidence of long-term health risks of ozone exposure, cumulative exposures are of interest for air quality regulation. The current form of the ozone air quality standard in the United States pertains to an extreme value (the design value) of the ozone distribution. Using atmospheric chemical transport modeling, we examine how well attainment metrics correlate with average exposure levels. We use forward sensitivity analysis to contrast the responses of two types of ozone metrics to widespread emission reductions. One such metric is based on extreme values of the ozone distribution used for attainment designation, while the other is the seasonal average ozone concentration indicative of long-term exposure levels. We find that in locations that have high day-to-day variability in ozone concentrations, design values are more sensitive to emission reductions and are least indicative of changing exposure levels with emission reductions

Attainment vs Exposure: Ozone Metric Responses to Source-Specific NO<i>_x</i> Controls Using Adjoint Sensitivity Analysis

We establish linkages between sources of NO_<i>x</i> emissions and two types of national ozone metrics in Canada and the U.S. using the adjoint of an air quality model. We define an attainment-based metric using probabilistic design values (PDVs) exceeding 65 ppb to represent polluted regions and define an exposure-based metric as the premature mortality count related to short-term ozone exposure, both in Canada and the U.S. Our results reveal differences in both temporally averaged and day-specific influences of NO_<i>x</i> emission controls across source locations. We find NO_<i>x</i> emission reductions in California and the eastern U.S. to be most effective for reducing attainment- and exposure-based metrics, amounting to a total reduction of 6500 ppb in PDVs and 613 deaths/season nationally from a 10% reduction in NO_<i>x</i> emissions from those source locations. While source controls in the remainder of the western U.S. are beneficial at reducing nonattainment, these reductions are less influential on ozone mortality. We also find that while exposure-based metrics are sensitive to daily emission reductions, much of the reduction in PDVs arises from controlling emissions on only a fraction of simulation days. We further illustrate the dependency of adjoint estimates of emission influences on the choice of averaging period as a follow-up to previous work

Attribution of Ozone Pollution Control Benefits to Individual Sources

Adjoint sensitivity analysis of numerical models provides a platform for directly linking public health effects with air quality for evaluating emission control policies in a more straightforward manner. We link epidemiological and valuation statistics to the adjoint of CMAQ and calculate sensitivities of short-term mortality-related benefits in Canada, the U.S. and Europe to anthropogenic NOx and VOC emissions across two continental domains. Our results show significant spatial variability in impacts of NOx and VOC emissions reduction on short-term mortality. We estimate that sensitivities of mortality-related benefits to 10 % NOx emissions reductions in major cities reach monetary values in excess of $635K/day in Europe and$355K/day in North America. We find that when the cumulative effects of anthropogenic emissions on O3 and NO2 population exposure are considered, NOx emissions reductions generally yield higher mortality-related benefits than the same relative reductions in VOC emissions

Low concentrations of fine particle air pollution and mortality in the Canadian Community Health Survey cohort

Background: Approximately 2.9 million deaths are attributed to ambient fine particle air pollution around the world each year (PM₂.₅). In general, cohort studies of mortality and outdoor PM₂.₅ concentrations have limited information on individuals exposed to low levels of PM₂.₅ as well as covariates such as smoking behaviours, alcohol consumption, and diet which may confound relationships with mortality. This study provides an updated and extended analysis of the Canadian Community Health Survey-Mortality cohort: a population-based cohort with detailed PM₂.₅ exposure data and information on a number of important individual-level behavioural risk factors. We also used this rich dataset to provide insight into the shape of the concentration-response curve for mortality at low levels of PM₂.₅. Methods: Respondents to the Canadian Community Health Survey from 2000 to 2012 were linked by postal code history from 1981 to 2016 to high resolution PM₂.₅ exposure estimates, and mortality incidence to 2016. Cox proportional hazard models were used to estimate the relationship between non-accidental mortality and ambient PM₂.₅ concentrations (measured as a three-year average with a one-year lag) adjusted for socio-economic, behavioural, and time-varying contextual covariates. Results: In total, 50,700 deaths from non-accidental causes occurred in the cohort over the follow-up period. Annual average ambient PM2.5 concentrations were low (i.e. 5.9 μg/m³, s.d. 2.0) and each 10 μg/m³ increase in exposure was associated with an increase in non-accidental mortality (HR = 1.11; 95% CI 1.04–1.18). Adjustment for behavioural covariates did not materially change this relationship. We estimated a supra-linear concentration-response curve extending to concentrations below 2 μg/m³ using a shape constrained health impact function. Mortality risks associated with exposure to PM₂.₅ were increased for males, those under age 65, and non-immigrants. Hazard ratios for PM₂.₅ and mortality were attenuated when gaseous pollutants were included in models. Conclusions: Outdoor PM₂.₅ concentrations were associated with non-accidental mortality and adjusting for individual-level behavioural covariates did not materially change this relationship. The concentration-response curve was supra-linear with increased mortality risks extending to low outdoor PM₂.₅ concentrations.Medicine, Faculty ofNon UBCPopulation and Public Health (SPPH), School ofReviewedFacult

A multiphase CMAQ version 5.0 adjoint

We present the development of a multiphase adjoint for the Community Multiscale Air Quality (CMAQ) model, a widely used chemical transport model. The adjoint model provides location- and time-specific gradients that can be used in various applications such as backward sensitivity analysis, source attribution, optimal pollution control, data assimilation, and inverse modeling. The science processes of the CMAQ model include gas-phase chemistry, aerosol dynamics and thermodynamics, cloud chemistry and dynamics, diffusion, and advection. Discrete adjoints are implemented for all the science processes, with an additional continuous adjoint for advection. The development of discrete adjoints is assisted with algorithmic differentiation (AD) tools. Particularly, the Kinetic PreProcessor (KPP) is implemented for gas-phase and aqueous chemistry, and two different automatic differentiation tools are used for other processes such as clouds, aerosols, diffusion, and advection. The continuous adjoint of advection is developed manually. For adjoint validation, the brute-force or finite-difference method (FDM) is implemented process by process with box- or column-model simulations. Due to the inherent limitations of the FDM caused by numerical round-off errors, the complex variable method (CVM) is adopted where necessary. The adjoint model often shows better agreement with the CVM than with the FDM. The adjoints of all science processes compare favorably with the FDM and CVM. In an example application of the full multiphase adjoint model, we provide the first estimates of how emissions of particulate matter (PM2.5) affect public health across the US

EDD mediates DNA damage-induced activation of CHK2

EDD, the human orthologue of Drosophila melanogaster “hyperplastic discs,” is overexpressed or mutated in a number of common human cancers. Although EDD has been implicated in DNA damage signaling, a definitive role has yet to be demonstrated. Here we report a novel interaction between EDD and the DNA damage checkpoint kinase CHK2. EDD and CHK2 associate through a phospho-dependent interaction involving the CHK2 Forkhead-associated domain and a region of EDD spanning a number of putative Forkhead-associated domain-binding threonines. Using RNA interference, we demonstrate a critical role for EDD upstream of CHK2 in the DNA damage signaling pathway. EDD is necessary for the efficient activating phosphorylation of CHK2 in response to DNA damage following exposure to ionizing radiation or the radiomimetic, phleomycin. Cells depleted of EDD display impaired CHK2 kinase activity and an inability to respond to DNA damage. These results identify EDD as a novel mediator in DNA damage signal transduction via CHK2 and emphasize the potential importance of EDD in cancer