Air Pollution: Is There an Association with Rheumatic Disease?

As for the risk associated with the timing of exposure, fetal and childhood exposure may be important. Several JIA and juvenile dermatomyositis studies demonstrate a heightened risk related to the gestational period and in children <5.5 years of age. The potential impact of ethnicity and underlying genetic background is evidenced by the Canadian data, showing an association of SARDs development particularly in First Nations patients.

There are significant issues with exposure definition in this area of research. Determination of exposure is typically based on place of residence, rather than work or commute exposures, or even accounting for duration of exposure. This simplification may introduce substantial exposure misclassification and may explain the large number of null results seen in the studies published to date.³⁵ Further, the variable latency of subclinical and clinical rheumatic disease can make determination of a clear link difficult. The ability to investigate personal exposures will be a significant advance in this field, while further accounting for the myriad potential genetic–environmental interactions that may explain disease development and onset, and improvements in disease detection and diagnosis.

Conclusion

To date, the evidence for an association between air pollutant exposure and the risk of developing rheumatoid arthritis or vasculitis is unclear; however, the odds of developing SARDs with exposure to PM2.5 do appear increased, particularly in the First Nations populations in Canada. Studies of exposure to air pollution in the gestational period or early childhood suggest an increased risk for developing JIA and juvenile dermatomyositis with multiple pollutants.

At this time, there is no definitive association determined for any air pollutant in any rheumatic disease.

Numerous challenges exist with regard to establishing a link between the exposure to air pollution and development of rheumatic disease, in particular the measurement of exposure, the contribution of different sources of air pollution and timing of exposure. Further refinements in methodology will be beneficial to improving estimates and truly determining whether air pollution does in fact play an important role in the development of rheumatic disease.

Dr. Sun

Gavin R. Sun, MD, is a third-year internal medicine resident with an interest in rheumatology. He completed medical school at the University of the Witwatersrand in Johannesburg, South Africa in 2006. Upon completion of his internship and community service, he emigrated to Canada in 2010. He previously practiced as a rural family physician in Vulcan, Alberta, between 2010 and 2012 before returning to residency at the University of Calgary.