Air pollution is increasingly recognized as an important and modifiable determinant of cardiovascular disease in urban communities. In a series of major epidemiological studies, it has been established that air pollution has adverse effects on cardiovascular health\cite{Dockery_1993}.
Recent epidemiological studies have shown that the greatest health threat due to air pollution is cardiovascular disease \cite{Lee_2014}.
Unsurprisingly, brief exposures to air pollution have been associated with increased cardiovascular-related morbidity and mortality from angina, myocardial infarction, arrhythmia and heart failure and this pathologic link have particular implications for low-income and middle-income countries\cite{Samet_2000}. These countries are rapidly developing, hence, air pollution concentrations are continuing to rise. Long-term exposure increases the risk of an individual from coronary heart disease and the main arbiter of these health effects seems to be the combustion-derived particulate matter. Because of its small size, particulate matter can be inhaled deep into the lungs, with a portion depositing in the alveoli and entering the pulmonary circulation and apparently the systemic circulation\cite{Sun_2010}. Inhalation of particulate matter or ultrafine particles (UFPs) triggers inflammatory responses in the lung and increases the release of inflammatory mediators into the blood. This, in turn, can lead to various changes in the cardiovascular system, such as an increase in blood coagulability and the progression of atherosclerotic lesions \cite{Nakane_2011}
In a study by Barnett et al. 2006 on the effects of air pollution on hospitalizations for cardiovascular disease in elderly people in Australia and New Zealand cities, they found that particulate matter (PM10 and PM2.5), NO2, SO2 and CO were significantly associated with higher admissions amongst the elderly (\(\ge\)65yrs) than the younger age group (15-64). O3 was the only pollutant that showed no association.  Findings from this study suggests that for a 0.9ppm increase in CO, elderly admissions increased for total cardiovascular disease (2.2%), all cardiac disease (2.8%), cardiac failure (6%), ischemic heart disease (2.3%) and myocardial infarction (2.9%). Their advanced age, frailty and with probably preexisitng heart conditions could be a reason for the vulnerability of the elderly population. Interestingly, these associations were found at concentrations that were below normal air quality health guidelines and the author's suggest that these guidelines have to be revised and lowered if possible. Lowering these guidelines will lead to improvements in cardiovascular health\cite{Barnett_2006}.
Another study by \cite{Liu_2015} on the association between air pollutants and cardiovascular disease nortality in China demonstrated that increases in NO2 and SO2 was significantly associated with cardiovascular disease mortality. These findings were consistent with a similar study done in Shanghai
                                                                                                                   
Ambient air  pollution and acute myocardial infarction
Acute Myocardial infarction is.....
Recent epidemiological and observational studies have demonstrated a significant increase in the incidence of adverse myocardial infarction in the immediate periods (hours to days) after exposure to high levels of atmospheric PM2.5\cite{Peters_2001}.
Pathophysiology of acute myocardial infarction