Clinical Scenario 1 for Particle Pollution
Mr. Richards is a man of 75 years with a history of hypertension, hyperlipidemia, diabetes, and atherosclerotic coronary artery disease. In spite of coronary artery bypass grafting, he still has residual flow-limiting coronary artery disease and stable angina. With therapeutic lifestyle changes and medications, Mr. Richards has achieved his goal for blood pressure, A1C, and serum lipids, and is generally free from angina except when doing very strenuous activity.
Mr. Richards' daily exercise routine includes walking in his neighborhood in the late afternoon. The initial part of his route takes him along a sidewalk adjacent to a busy road carrying heavy afternoon automobile, bus, and truck traffic. As he returns to his home, his route takes him up a steep hill. Most of the time, he can complete his walk in 60 minutes without shortness of breath or angina.
Occasionally, Mr. Richards experiences dyspnea with exertion as well as substernal chest pain and pressure when walking up the hill. He denies pleuritic chest pain, nausea, or diaphoresis. The discomfort quickly subsides when he stops walking. He has not felt the need to use sublingual nitroglycerin to relieve the chest pain. Of note is that he reports that his symptoms are more likely to occur when the air has been hazy for a few days. He is concerned that the intermittent chest pain is related to worsening of his coronary artery disease, and he seeks assistance from his family medicine physician.
With careful questioning, it is established that his pattern of angina is unchanged, and his concern is based on the variability of angina when walking up the hill at the end of his exercise route. It is unlikely that the intermittent anginal pain is related to the progression of his coronary artery disease or the development of unstable angina. The pattern of angina remains essentially the same but appears to have a slightly lower threshold when preceded by several days of air pollution.
Evidence is mounting that particle pollution, possibly in combination with ozone ozone Ground level ozone is not emitted directly into the air, but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC). This happens when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources chemically react in the presence of sunlight. Ozone at ground level is a harmful air pollutant, because of its effects on people and the environment, and it is the main ingredient in “smog." or other gaseous pollutants, can affect endothelial function and might explain an increase in ischemic symptoms in the presence of high levels of particle pollution. Co-morbid conditions such as advanced age, hypertension, diabetes, and obesity appear to increase one’s susceptibility to the effects of particle pollution. Particle pollution is greatest on and adjacent to the roads, and the concentration of ultrafine particles decreases rapidly as one moves away from the road. Among individuals with established ischemic heart disease, exposure to fine particle pollution modifies the magnitude of exercise-induced ST depression, suggesting that exposure to particle pollution worsens ischemia.
Mr. Richards was congratulated for his efforts to modify his risk factors and encouraged to continue lifestyle changes and adhere to the medications for hypertension, diabetes, and hyperlipidemia. In particular, he was encouraged to continue walking six days each week, but was advised to change his route to exclude walking along a busy highway. He was advised to monitor the EPA's AirNow website for information on particle pollution and ozone and to do his walking indoors if the air is hazy or if particles and/ozone are predicted to be in the orange range (unhealthy for sensitive persons) or worse. He was also advised to exercise in the morning when temperatures and levels of ozone are likely to be lower.