Innate immune response to ozone insult and Streptococcus pneumoniae Air pollution is a major health concern, especially for those that live in densely populated urban areas. Breathing in high levels of contaminants increases the likelihood of acquiring serious medical conditions, such as asthma and bacterial pneumonia, and long-term exposure can lead to more serious complications, like chronic obstructive pulmonary disease (COPD). Ozone is a particularly hazardous chemical that is one of the more common air contaminants.