Grantee Research Project Results

2017 Progress Report: Climate Change, Indoor Ozone and Vascular Function

EPA Grant Number: R835759
Title: Climate Change, Indoor Ozone and Vascular Function
Investigators: Kipen, Howard , Ryan, P. Barry , Barr, Dana Boyd , Georgopoulos, Panos G. , Weschler, Charles J. , Lioy, Paul J. , Ohman-Strickland, Pamela , Meng, Qingyu
Institution: Rutgers
EPA Project Officer: Chung, Serena
Project Period: May 1, 2015 through April 30, 2018 (Extended to April 30, 2019)
Project Period Covered by this Report: May 1, 2017 through April 30,2018
Project Amount: $999,975
RFA: Indoor Air and Climate Change (2014) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Climate Change , Air

Objective:

Examine how changes in ambient O₃ as a consequence of climate change in urban areas may affect indoor air quality through both a direct effect on indoor O₃ concentration and an indirect effect on indoor chemistry.
Examine whether indoor exposures to air pollutants and cardiorespiratory responses can be modified by the use of a portable air cleaner.
Model climate change impacts on ambient O₃ pollution, indoor exposures to O₃ , O₃ /alkene reaction products, and cardiovascular health outcomes in the elderly.

Progress Summary:

A. Objectives 1 and 2:

Sampling has been completed (September 2017 for Rutgers University and October 2017 for Emory University). A total of 20 subjects in 18 homes were recruited at each site (see Table for demographic data). As the overall study, based on the primary microvascular function endpoint, was powered for 15 subjects at each site we are confident that we have sufficient power to test the biological hypotheses. The focus of this past year has been specimen analysis (exhaled breath condensate (EBC) and 6-methyl-5-hepten-2-one (6-MHO)) and the processing of the real time air sampling data. Nitrite concentrations in all EBC samples have been measured. 6-MHO analysis has been completed and is undergoing quality analysis review. Processing of the real-time air monitoring data (ozone, PM_2.5, black carbon, ultrafine particles, CO₂) is ongoing.

Air Monitoring Data/Samples

Real time instruments and integrated samplers were used to monitor concentrations during each exposure period (2 days with filtration; 2 days with no filtration). Preliminary analyses are now available for most of the measurements of pollutants and health outcomes. Laboratory assay of the products of ozone chemistry is still pending. Using paired t-tests to compare median values, black carbon (BC) concentrations were significantly lower in the filtered period compared to the sham (average median concentrations 70 v. 432 ng/cm³; p<0.001). Similarly, ozone, PM_2.5 and particle number concentrations (PNC) were also significantly lower in the filtered period (O₃: 5.07 v. 6.12 ppb; p=0.008; PM_2.5: 5.21 v. 9.19 µg/m³; p<0.001, and PNC: 742 v. 3240 particle/cm³; p<0.001, respectively). These preliminary data suggest that use of the air cleaners was able to achieve significant reductions in indoor pollutant concentrations.
A system for consistently recording building characteristics, subject activities and location, and window use is being incorporated into our analyses. It appears that even in homes that opened windows significant reductions in BC were observed and borderline significant reductions were seen in PNC.

Biological Data/Specimens

Reactive Hyperemia Measurement: EndoPAT was performed on all 40 subjects at three time points (baseline, after sham treatment, and after filtration). The mean reactive hyperemia index (RHI) at baseline, after sham treatment, and after filtration were 1.88, 1.90, and 1.77, respectively. Preliminary analysis showed that there was no significant difference based on treatment status (paired t-test). The analyses were then repeated for the 17 subjects not on vasoreactive medications and the results were largely unchanged. Final statistical models with appropriate adjustment for confounders will be completed in the final year (no cost extension).

Fractional Exhaled Nitric Oxide (FeNO) Measurement: Mean FeNO concentrations at baseline, after the sham treatment, and after filtration were 25, 24, and 26 ppb, respectively, with no significant difference based on treatment status (paired t-tests). Four subjects were excluded from this endpoint based on the use of anti-inflammatory medications. The results were largely unchanged (26, 24, and 26 ppb, at baseline, after sham treatment, and after filtration, respectively).

Exhaled Breath Condensate (EBC) Specimens for Nitrite: Sufficient samples were collected from 39 subjects (19 at Rutgers and 20 at Emory). Preliminary analysis showed that, overall, mean nitrite concentration decreased from baseline by 0.51 µM after sham treatment and by 0.04 µM after filtration, with no significant difference between the treatment periods.

These preliminary data indicate no significant changes in the cardiopulmonary biomarkers to accompany the reductions in pollutant levels.

B. Objective 3: Computational modeling efforts during the current reporting period were pursued according to the stated objectives of Modeling Tasks 1, 2 and 3 of the Project Work Plan.

Modeling Task 1 involves the refinement and evaluation of indoor air quality modules to incorporate current information on relevant indoor ozone chemical reactions.

Work on Modeling Task 1 continued testing, evaluation and refinement of indoor air quality (IAQ) modules incorporating state-of-the-art in indoor ozone photochemistry. As an example, secondary organic aerosol (SOA) formation through reaction of ozone with squalene in the indoor environment has been implemented and coded in Matlab; model simulations were evaluated with data available in the literature. On-going work focuses on sensitivity analyses aiming to characterize the impact of system parameters on airborne concentrations of gaseous and aerosol species. These IAQ modules will be further calibrated utilizing the information collected through the present project.

Modeling Task 2 involves the incorporation of the indoor air quality (IAQ) modules developed in Task 1 into the Modeling Environment for Total Risk in One Atmosphere (MENTOR-1A) system.

Currently on-going work on Modeling Task 2 focuses on coupling the IAQ modules developed under Task 1 with the neighborhood scale air quality characterization components of MENTOR. These components "downscale" outputs of a customized version of the Community Multiscale Air Quality (CMAQ) model at census tract resolution using modified Spatio-Temporal Random Field (STRF) approaches; during the current project period, refinements of the downscaling method have been evaluating the coupling of machine learning methods with the Bayesian Maximum Entropy approach.

Modeling Task 3 has been adapted from the original work plan to focus on the analysis of photochemical air quality modeling results of base (2017) and future (2047) simulations of the study periods (May to September), employing the Community Multiscale Air Quality model (CMAQ) on a regional 3-dimensional grid with downscaling over the two selected study areas of New Brunswick, NJ and Atlanta, GA.

On-going work is employing a multi-model system currently operational at the Computational Chemodynamics Laboratory (CCL) of EOHSI, that includes, in addition to CMAQ, the Modeling Environment for Total Risk studies in a "One-Atmosphere" framework (MENTOR-1A), the Weather Research and Forecasting (WRF) model, the Sparse Operator Kernel Emissions (SMOKE) model, the Meteorology Chemistry Interface Processor (MCIP), and other computational tools designed to support studies of climate change effects on air quality and human exposures. During the present project reporting period, efforts within Modeling Task 3 have continued to involve analysis of CMAQ model inputs and outputs for base and future air quality simulations focusing on the Eastern US. Work completed during the current reporting period included iterative comparative analyses of CMAQ-derived hourly ozone predictions for May, June, July, August and September of 2017 (base year) and 2047 (future year) of the two study areas of New Brunswick, NJ and Atlanta, GA.

Future Activities:

Data cleaning for the remaining pollutants, including ozone chemistry is underway and determination of air exchange rates for each dwelling is ongoing. Merging all of these results with Dr. Georgopoulos' climate and ozone models will be accomplished in this final year.

Journal Articles:

No journal articles submitted with this report: View all 6 publications for this project

Progress and Final Reports:

Original Abstract

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.