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By M.C. Gustavo López Badilla (1) and Dr. Rogelio Ballesteros (2)
Studies carried out by various researchers indicate that exposure to O3, at low and high levels and for short and long periods, is a very harmful pollutant for health and can lead to death.
This work makes a contribution to the study of environmental health. According to previous studies, we created the hypothesis that the behavior of O3 can explain the generation of cardiovascular diseases (CVD). To test this hypothesis, a study was carried out with 80 people (40 healthy and 40 with heart disease) (men and women). Both people received medical attention, to carry out check-ups in a few days (cardiac index, pressure and resistance of the peripheral circulations of the central pulmonary system, and oxygen saturation), and these clinical data were analyzed together with the data of the pollutant ( ozone). The production of ozone with and without calm winds, at the surface level, is due to the generation of solar radiation and temperature, in addition to poor planning and excessive city traffic. A model was developed to predict the behavior of ozone based on solar radiation and temperature of the city of Mexicali, and thereby obtain clinical data at the correct times to develop the correlation. The information analyzed (hourly, daily, weekly, monthly and by season (winter and summer) was from 1999 to 2000. The information on the pollutant was provided by the four Environmental Monitoring Stations (EMA) located in strategic places in the city and the Health data were obtained from samples of people from four health clinics (CS) close to the EMA, who were treated during the study period. The diseases analyzed are: arterial hypertension (with a higher index), ischemic heart disease ( IHD) and cardiac arrhythmia. 80 people were located (40 people with CVD and 40 healthy, close to patients with heart problems / 20 for each clinic). The regression analyzes showed values of the determination coefficient greater than 0.7 and the tests F were fulfilled for all zones and relationships, indicating that ozone behavior can explain at least 70% the generation of cardiovascular diseases.
The effect that solar radiation produces on ozone (O3) is very important for its formation. Ozone pollution is mainly caused by cars, influenced by solar radiation, as shown below:
NO2 + light energy (430nm) = O + NO (1)
O + O2 = O3 (2)
It is said that the increase in O3 levels, in winter and summer, produces an effect on the respiratory system and as a consequence in cardiovascular diseases. Studies carried out by various researchers indicate that exposure to O3, at low and high levels and for short and long periods, is a very harmful pollutant for health and can lead to death. According to Schwartz (Schwartz, 1991), ozone was a predictor of deaths, mainly cardiovascular ones. In a Los Angeles study (Kinney and Ozkaynak, 1991), ozone is a toxic oxidant that is associated with CVD deaths. In 1992, Kinney and Ozkaynak (Kinney and Ozkaynak, 1992), decided to carry out an analysis again in New York, including meteorological variables (temperature and relative humidity), concluding that O3 explains 10% of daily deaths from heart problems . In Philadelphia, Li and Roth (Li and Roth, 1995) point out that O3 is a harmful pollutant in people over 65 years of age, where O3, PST (Total Suspended Particles) and SO2 (Sulfur Dioxide) were monitored; indicating that ozone was the one that most influenced the generation of ECV. This indicates that O3 exposure influences people with heart problems, mainly people over 65 years of age.
The information used is from the period 1999 to 2000, and we tried to get an idea of what happens when correlating the ozone levels at different times in several days in winter and summer, so the data from the different EMA and clinics near them. The ozone information was obtained from the environmental monitoring carried out by the United States Environmental Protection Agency (EPA), in the four EMAs, while the patient data was collected by consulting with CVD patients, in the four public health clinics attached to the EMA. For the sampling of patients with CVD, it was necessary to identify people with problems of arterial hypertension, ischemia of the heart and cardiac arrhythmias; and monitor them through home visits and health clinics. Data from the health sector indicate that in the last five years the rate of patients with heart problems has increased (ISESALUD, 2001).
The study consisted of analyzing the effect that ozone produces in the generation of cardiovascular diseases. Analyzes were carried out in the different hourly periods of several days in the winter and summer season, for each variable and correlations were made. The first step was to identify the high and low levels of ozone per hour in some days analyzed from 1999 to 2000 and later to locate patients with CVD and detect what symptoms they suffered in those respective periods of ozone behavior. 80 were located (40 patients with cardiovascular problems and 40 healthy people who live near people with CVD).
Figure 1 shows the location of the EMA and CS from where the data for the study were obtained. Table I indicates the values of the coefficients of determination of the periods analyzed with high and low levels of O3. It is observed that in all associations the value of the coefficient is greater than 0.7. Graph 1 represents June 18, 1999, for EMA-UABC and CSH, with a coefficient of determination of 0.73. This graph represents ozone concentration levels and CVD patient visits. Values are low from 1am to 6am, then increase from 9am to 12pm, with the highest rates being observed, as indicated by George regarding cardiovascular diseases (George, 1993). The values from 1pm to 5pm decrease and from 5pm to 7pm the indices are low, then they increase, but they are not very high. Graph 2 shows the EMA-CBTIS21 and the CSPH on December 9, 2000 with a coefficient of determination of 0.71. The values from 1am to 7am are low, then they increase and the highest is around 12pm. The values from 1pm to 4pm decrease, from 5pm to 12am they increase, but do not reach the highest value. Table II indicates the analysis of the F-test of the EMA ITM and the 1999 CSGO. This table shows that F0 = F (1,19,0.1), meaning that the F-Test was passed. Table II indicates the analysis of the F-test of the EMA CBBC and the CSDN of 2000. This table shows that F0 = F (1,18,0.1), meaning that the F-Test was approved
The model to predict ozone based on temperature and solar radiation is the following:
Y = 0.008X12 + 0.267X1 + 0.001X2 + 0.0067;
where X1 is the temperature and X @ is the solar radiation.
DISCUSSION OF RESULTS
It is important to consider that exposure to O3, particularly people with heart disease, carries a high risk that can lead to death. This study, like others carried out in different cities around the world, indicates that there is at least a 70% relationship between this harmful pollutant and cardiovascular diseases. It should be clarified that the analyzes were in hourly averages, because the ozone standard is 0.11 ppm per hour.
The effect of solar radiation and vehicular traffic on ozone production, influences O3 to cause consequences in the human population, mainly in people who suffer from heart problems. This study shows that with the coefficients obtained, at least 70% explain that there is an association between ozone and cardiovascular diseases. In the summer season there are high levels of solar radiation and ozone and in winter the values of the two variables decrease. Even when O3 particles in summer disperse more easily and quickly into the atmosphere, there is a harmful effect on health, as in winter, that the levels decrease, but the Greenhouse Effect keeps the ozone particles near the earth's surface, having the same effect on CVDs.
Schwartz J. Particulate air pollution and daily mortality in Detroit. Environ Res; 56: 204-213, 1991
Kinney, P.L., and H. Ozkaynak. Associations of daily mortality and air pollution in Los Angeles County. Environ Res. 54: 99-120. 1991.
Kinney, P.L., and H. Associations between ozone and daily mortality in Los Angeles and New York City. Am Rev Respiratory Diseases, 145: A95. 1992.
Li and Roth. Daily mortality analysis by using different regression models in Philadelphia county, 1973-1990. Inhalation Toxicology 7, 45-58. nineteen ninety five
ISESALUD, Report of Pathologies of the State of Baja California - 2001; 2001.
Figure 1. Location of the EMA and CS in Mexicali
Table 1. Correlation coefficients of O3 and CVD in Mexicali (1999 and 2000)
Table II. Test F of data from: EMA (ITM) / CS-GO (1999)
Table III. Test F data from: EMA (CBBC) / CS-DN (2000)
Graph 1. Realization of O3 (High Levels) and CVD in Mexicali (June 18, 1999). UABC-CSH
Graph 1. Realization of O3 (High Levels) and CVD in Mexicali (November 22, 2000). CBTIS21-CSPH
(1) Researcher at the Institute of Engineering, U.A.B.C., Mexicali, B.C. e-mail: [email protected]
(2) Cardiologist from ISESALUD, Mexicali, B.C.