Arthritis Care & Research Vol. 67, No. 11, November 2015, pp 1609–1614 DOI 10.1002/acr.22603 V C 2015, American College of Rheumatology BRIEF REPORT Exposure to Air Pollutants and Disease Activity in Juvenile-Onset Systemic Lupus Erythematosus Patients ELISABETH C. FERNANDES, 1 CLOVIS A. SILVA, 1 ALF  ESIO L. F. BRAGA, 2 ADRIANA M. E. SALLUM, 1 L  UCIA M. A. CAMPOS, 1 AND SYLVIA C. L. FARHAT 1 Objective. To investigate the association between exposure to air pollutants in the Sao Paulo metropolitan area and disease activity in juvenile-onset systemic lupus erythematosus (SLE) patients. Methods. A longitudinal panel study based on 409 consecutive visits of juvenile-onset SLE patients living in the Sao Paulo metropolitan area was carried out. Disease activity was evaluated in accordance with the Systemic Lupus Erythe- matosus Disease Activity Index 2000 (SLEDAI-2K), and the patients were divided into 2 groups: those with SLEDAI scores £8 and those with SLEDAI scores >8. Daily concentrations of inhaled particulate matter (PM 10 ), sulfur dioxide, nitrogen dioxide (NO 2 ), ozone, and carbon monoxide (CO) were evaluated on the 21 days preceding the medical visits. A generalized estimation equation model was used to assess the impact of these measurements on SLEDAI-2K scores, considering the fixed effects for repetitive measurements. The models were adjusted for erythrocyte sedimentation rate, corticosteroid use (daily and cumulative doses), antimalarial use, the use of immunosuppressive agents, the presence of infection 20 days preceding the medical appointment, and the minimum temperature and relative humidity outdoors. Results. PM 10 , NO 2 , and CO were risk factors for juvenile-onset SLE disease activity (SLEDAI-2K score >8) approxi- mately 2 weeks after exposure. A 13.4 mg/m 3 increase in the PM 10 moving average (from lag 12 to lag 15) was associat- ed with a 34% increase (95% confidence interval 7.0–68.0) in the risk of a SLEDAI-2K score >8. Conclusion. This is the first study to show that exposure to inhaled pollutants may increase the risk of disease activity in children with juvenile-onset SLE in a large urban center. Introduction Air pollution is composed of a heterogeneous mixture of gases and particles that includes nitrates (NO), sulfur dioxide (SO 2 ), ozone (O 3 ), lead, toxic products of tobacco smoke, carbon monoxide (CO), volatile organic com- pounds, and particulate matter (PM) (1). Many of the harmful effects on human health caused by tropospheric pollutants have been linked to particles smaller than 10 mm in diameter (PM 10 ). These particles mainly origi- nate from vehicle tailpipe emissions in urban areas. Fine particles are classified as those smaller than 2.5 mm in diameter, while those classified as ultrafine are smaller than 0.1mm in diameter (1). A significant portion of PM is composed of sulfates, nitrates, metals, hydrocarbons, and other substances in its adsorbed molecules (1). In this regard, this is a major public health hazard in large cities (2–4), and children and adolescents are sus- ceptible to the effects of air pollution. However, there are few studies evaluating the association between exposure to air pollutants and autoimmune diseases in this popula- tion (4,5), and to our knowledge no study has assessed the influence of air pollutants on the disease activity of juvenile-onset systemic lupus erythematosus (SLE) patients. Therefore, the objective of this study was to investigate the association between daily exposure to concentrations Dr. Silva’s work was supported by the Conselho Nacional de Desenvolvimento Cient  ıfico e Tecnol ogico (CNPQ 302724/2011-7 and 472155/2012-1), the Federico Founda- tion, and N ucleo de Apoio  a Pesquisa Sa ude da Crianc ¸a e do Adolescente da USP. Dr. Farhat’s work was supported byFundac¸~ ao de Amparo  a Pesquisa do Estado de S~ ao Paulo (13/21508-2). 1 Elisabeth C. Fernandes, MD, MS, Clovis A. Silva, MD, PhD, Adriana M. E. Sallum, MD, PhD, L ucia M. A. Campos, MD, PhD, Sylvia C. L. Farhat, MD, PhD: Faculdade de Medicina da Universidade de S~ ao Paulo, S~ ao Paulo, Brazil; 2 Alf esio L. F. Braga, MD, PhD: Faculdade de Medicina da Universidade de S~ ao Paulo, S~ ao Paulo, and Universidade Catolica de Santos, Santos, Brazil. Address correspondence to Sylvia C. L. Farhat, MD, PhD, Faculdade de Medicina da Universidade de S~ ao Paulo, N ucleo de Estudos em Epidemiologia Ambiental, Labo- rat orio de Poluic¸~ ao Atmosf erica Experimental, Avenida Dr. Arnaldo, 455, 1  andar, sala 1304, S~ ao Paulo, SP, Brazil, 01246-903. E-mail: sylvia.farhat@gmail.com. Submitted for publication November 9, 2014; accepted in revised form April 14, 2015. 1609