It is well characterized that exposure to air pollutants is deleterious to human health. However, there is currently a gap in studying the effects of long term, low levels of exposure to pollution. The central objective of this study was to determine the effect(s) of environmental pollutants on health in the companion dog. This study used the vast Health and Life Experience Survey, Environment survey, Health Conditions survey, and Cancer Conditions survey from the Dog Aging Project as well as publicly available pollution data from the Environmental Protection Agency. These data along with a composite exposure measure, generated to accurately capture average exposure, were used to assess and model how exposure to environmental pollutants can affect reported health and disease. Overall, higher levels of exposure were found to be associated with a higher number of reported diseases. This study also included paired deoxyribonucleic acid (DNA) methylation data for a subset of dogs to investigate possible molecular mechanisms behind these observed associations. It was found that differential DNA methylation is not only associated with exposure to environmental pollutants but also that these changes mimic observed age-related changes. Due to companion dogs sharing their environment with humans, our findings may be applicable to human health. Continuing investigations into how poor air quality causes detrimental effects to health and disease will be especially valuable for more vulnerable populations.