Effect of air pollution on daily morbidity in Karachi, Pakistan

Levels of daily particulates (PM2.5) were monitored at two sites in Karachi, Pakistan. One site (Korangi) is an industrial and residential neighborhood, while the other (Tibet Center) is a commercial and residential area near a major highway. Monitoring was done daily for a period of six weeks during spring, summer, fall and winter. Particulate levels were extraordinarily high, with the great majority of days falling into the “unhealthy for sensitive groups” or “very unhealthy” categories. The mean PM2.5 levels in Karachi exceeded the WHO’s 24 hour air quality guideline almost every day and often by a factor of greater than 5-fold. Daily emergency room (ER) visits and hospital admissions for cardiovascular diseases were obtained by review of medical records at three major tertiary and specialized hospitals. ER and hospitalizations were reported relative to days in which the concentration of PM2.5 was less than 50 μg/m3, and by 50 μg/m3 increments up to 300 μg/m3. There were statistically significant elevations in rates of hospital admissions at each of the PM2.5 categories at the Korangi site, and at concentrations >150 μg/m3 at the Tibet Center site. ER visits were significantly elevated only at PM2.5 concentrations of between 151 and 200 μg/m3 at both sites. These results show that the extremely elevated concentrations of PM2.5 in Karachi, Pakistan are, as expected, associated with significantly elevated rates of hospital admission, and to a lesser extent, ER visits for cardiovascular disease.