Measurement of exposure is another important consideration when interpreting studies of pollution's effects on health. Largely, the studies employed place of residence prior to or at diagnosis to determine exposure, without accounting for places where leisure time, occupation, or daily commute might impact risk, resulting in exposure misclassification . The measurement period, duration, and latency period between subclinical and clinical rheumatic diseases might result in wrongfully attributing exposure to the diagnosis period only. The varied composition of air pollution can make it challenging to overcome the confounding effects of concurrent pollutant exposure. Here distance to roadway studies have been conducted [18, 30], but further information on which pollutants create this heightened risk is required. Yet another consideration proposed is that the range and variability in pollution levels must be sufficiently large to detect associations, which may allow detection of risks limited to higher exposure levels .