Anderson, F. , Carson, A. , Whitehead, L. and Burau, K. (2014) Spatiotemporal Analysis of the Effect of Ozone and Fine Particulate on CVD Emergency Room Visits in Harris County, Texas. Open Journal of Air Pollution, 3, 87-99. doi: 10.4236/ojap.2014.34009.
This article is about finding a connection between humidity, air pollutants, specifically ozone and PM2.5, and cardiovascular disease and effects. This study was conducted in Harris County and took into account total ER visits, as well as temperature, humidity, and pollutant concentrations based on a logistic regression model. They found statistically significant increases in the odds of cardiovascular disease diagnoses with a rise in pollutant concentration and humidity (p-value < 0.001).
Faye Anderson, an author of this paper, did another study in Houston about how age, race, and gender factor into COPD and the disparities caused by them. Arch Carson also contributed to this study study, as well as the other paper featuring Faye Anderson. He is a professor of Epidemiology, Human Genetics, and Environmental Sciences at the University of Texas Health School of Public Health. This paper is affiliated with Texas A&M AgriLIFE Research Center.
The study found that same-day concentrations for ozone and PM2.5 were associated with cardiovascular disease (CVD) ER visits. The study also found an increase in incidence proportions for CVD cases by a factor of from 2004-2009, which is the time interval being analyzed. Finally, this study saw that black people and males had higher incidences of CVD diagnoses.
The relationship between ozone and PM2.5 and CVD is supported by the logistic regression model used for this study. When adjusted and unadjusted for other risk factors, both PM2.5 and ozone have odds ratios and 95% confidence intervals that are greater than 0.99, indicating that there is a strong relationship between these two factors and CVD visits. The increase in incidence proportion for CVD is supported by the massive immigration after Hurricane Katrina and Rita in 2005, where one million people immigrated to Houston within an 18 month interval after both hurricanes. Most of these people were poor and African-American, so it is likely that they would go to the ER for health issues, leading to a higher incidence of CVD diagnoses. Black people and males being more likely to have CVD diagnoses is supported by the high odds ratio used in this study. Black people, regardless of gender, had an odds ratio of 1.095, while males, regardless of race, had an odds ratio of 1.591 when both were adjusted for other risk factors.
“This is the first study to explore spatial and temporal trends over multiple years for Harris County, Texas. While majority of studies focus on either spatial or temporal association between exposure to O3 and/or PM2.5 and CVD ER visits, this study investigates the relationship both temporally and spatially.”
“This study demonstrated that there are statistically significant associations between ER visits for CVD diagnosis in Harris County, with joint exposure to O3 and PM2.5 of the same day and previous day. The increase of CVD cases as well as association between humidity and the numbers of CVD cases.”
“ The logistic prediction equation used was: logit[P(CVD diagnosis = 1)] = intercept + B1 * temperature + B2 * relative humidity + B3 * west-east wind + B4 * south-north wind + B5 * wind speed + B6 * age + B7 * race + B8 * sex + B9 * day of the week + B10 * PM25 + B11 * O3 + B12 * O3lag 1 + B13 * PM25lag 1.”
This study counted ER visits from 2004-2009. CVD cases included visits for heart rhythm irregularities, heart disease, stroke, and heart failure. Ozone and PM2.5 concentration was collected on the hour. Gaussian regression was used to calculate ozone and PM2.5 concentration away from the the collection sites. The logistic equation used for final calculations was logit[P(CVD diagnosis = 1)] = intercept + B1 * temperature + B2 * relative humidity + B3 * west-east wind + B4 * south-north wind + B5 * wind speed + B6 * age + B7 * race + B8 * sex + B9 * day of the week + B10 * PM25 + B11 * O3 + B12 * O3lag 1 + B13 * PM25lag 1 .
Health disparities are addressed by taking into account race, age, and gender as factors that may relate to CVD cases. Also, this study takes into account the influx of people after Hurricane Katrina and Rita when acknowledging the increase in CVD cases, as many of these people who came were poor and more likely to go to the ER for any health issues.
According to Google and the journal this study was published in, this paper has yet to be referenced by other studies. Since this paper was published in 2014, it will take some time for other reports to come around and use this study.
Five out of the twenty one papers cited in the report come from government sources at either the state or national level. The Kenneth Sexton article linked on the Wiki is used as a reference in this article.
I first looked at a paper made by the same authors as this report on spatiotemporal disparities of COPD ER visits. They used almost identical methods for calculating logistic regression when finding the relationship between each risk factor and COPD (http://www.scirp.org/journal/PaperInformation.aspx?PaperID=53779 ).
Next, since I am unfamiliar with most statistical methods, I decided to look up some of the terms that they used, such as 'kriging'. This is a form of Gaussian regression used to give the best unbiased linear prediction of intermediate values. This study used kriging when estimating ozone and PM2.5 concentrations between monitoring sites to forma contour ma of concentration all across Houston.
Finally, I looked at the publicly available ozone and PM2.5 data to see what the numbers were like between 2004 and 2009. I specifically looked at all of the monitoring sites listed on the TCEQ website. In 2004, the eight-hour maximum ozone concentration for all of Houston was 135ppb for the site at Clear Creek High School. By 2009, the concentration had gone down to 92ppb, which is still unsafe for people with respiratory ailments, but a drastic reduction nonetheless. As for PM2.5, the average concentration was 14.5 micrograms/m3 in 2004, whereas it had dropped to 12.6 micrograms/m3 in 2009.
Addendum:
This study highlights that it is not just respiratory ailments which are exacerbated by air pollutants. CVD cases cost over $2 billion, so now that I connection has been made between this and air pollutants, acting on this information should hopefully lead to a reduction in both respiratory and cardiovascular health care expenditures.
This article is about finding a connection between humidity, air pollutants, specifically ozone and PM2.5, and cardiovascular disease and effects. This study was conducted in Harris County and took into account total ER visits, as well as temperature, humidity, and pollutant concentrations based on a logistic regression model. They found statistically significant increases in the odds of cardiovascular disease diagnoses with a rise in pollutant concentration and humidity (p-value < 0.001).
“This study demonstrated that there are statistically significant associations between ER visits for CVD diagnosis in Harris County, with joint exposure to O3 and PM2.5 of the same day and previous day. The increase of CVD cases as well as association between humidity and the numbers of CVD cases.”
“ The logistic prediction equation used was: logit[P(CVD diagnosis = 1)] = intercept + B1 * temperature + B2 * relative humidity + B3 * west-east wind + B4 * south-north wind + B5 * wind speed + B6 * age + B7 * race + B8 * sex + B9 * day of the week + B10 * PM25 + B11 * O3 + B12 * O3lag 1 + B13 * PM25lag 1.”
Next, since I am unfamiliar with most statistical methods, I decided to look up some of the terms that they used, such as 'kriging'. This is a form of Gaussian regression used to give the best unbiased linear prediction of intermediate values. This study used kriging when estimating ozone and PM2.5 concentrations between monitoring sites to forma contour ma of concentration all across Houston.
Finally, I looked at the publicly available ozone and PM2.5 data to see what the numbers were like between 2004 and 2009. I specifically looked at all of the monitoring sites listed on the TCEQ website. In 2004, the eight-hour maximum ozone concentration for all of Houston was 135ppb for the site at Clear Creek High School. By 2009, the concentration had gone down to 92ppb, which is still unsafe for people with respiratory ailments, but a drastic reduction nonetheless. As for PM2.5, the average concentration was 14.5 micrograms/m3 in 2004, whereas it had dropped to 12.6 micrograms/m3 in 2009.
Addendum:
This study highlights that it is not just respiratory ailments which are exacerbated by air pollutants. CVD cases cost over $2 billion, so now that I connection has been made between this and air pollutants, acting on this information should hopefully lead to a reduction in both respiratory and cardiovascular health care expenditures.