The impact of climate and traffic-related NO 2 on the prevalence of asthma and allergic rhinitis in Italy

R. De Marco, A. Poli, M. Ferrari, S. Accordini, G. Giammanco, M. Bugiani, S. Villani, M. Ponzio, R. Bono, L. Carrozzi, R. Cavallini, L. Cazzoletti, R. Dallari, F. Ginesu, P. Lauriola, P. Mandrioli, L. Perfetti, S. Pignato, P. Pirina, P. Struzzo

Research output: Contribution to journalArticlepeer-review


Background: Environmental factors are likely to be involved in explaining the wide geographical variation in asthma and atopic diseases that has been documented in many recent epidemiological studies. Aim: To evaluate to what extent climate and outdoor NO 2 pollution can explain the geographical variation in the prevalence of asthma and allergic rhinitis, and to estimate the relative risk for exposure to different levels of these two factors. Methods: The impact of climate and long-term exposure to nitrogen dioxide (NO 2) pollution on asthma and allergic rhinitis was assessed in a cross-sectional study, carried out during 1998 to 2000 on young adults aged 20 to 44 years (n = 18 873), living in 13 areas from two different Italian climatic regions (subcontinental and Mediterranean). Results: Mediterranean areas had a significantly higher prevalence of asthma-like symptoms (P <0.001), higher annual mean temperature (16.2°C vs. 12.9°C), lower temperature range (16.0 C° vs. 22.1 C°) and lower NO 2 levels (31.46 μg/m 3 vs. 57.99 μg/m 3) than subcontinental ones. Mediterranean climate was associated with an increased risk of wheeze (OR = 1.23; 95% CI 1.13 to 1.35), tightness in the chest (OR = 1.21; 95% CI 1.11 to 1.33), shortness of breath (OR = 1.21; 95% CI 1.08 to 1.36) and asthma attacks (OR= 1.19; 95% CI 1.07 to 1.31). After adjusting for climate, an increase of 18.3 μg/m 3 in NO 2 levels moderately increased the risk of asthma attacks (OR = 1.13; 95% CI 0.98 to 1.32), tightness in the chest (OR = 1.11; 95% CI 0.98 to 1.26) and wheeze (OR = 1.11; 95% CI 0.96 to 1.28). When the levels of outdoor NO 2 exposure rose, the prevalence of allergic rhinitis increased significantly in the Mediterranean region (OR = 1.38; 95% CI 1.12 to 1.69), but not in the subcontinental one (OR = 1.03; 95% CI 0.83 to 1.28). Conclusion: Our results show that the prevalence of asthma increases when annual mean temperature increases and temperature range decreases. Furthermore, climate interacts with NO 2 outdoor exposure, increasing the risk for allergic rhinitis in people exposed to high stable temperatures. A long-term role for the effect of traffic pollution on asthma is also suggested.

Original languageEnglish
Pages (from-to)1405-1412
Number of pages8
JournalClinical and Experimental Allergy
Issue number10
Publication statusPublished - 2002


  • Allergic rhinitis
  • Asthma
  • Climate
  • Outdoor NO2 pollution
  • Traffic-related pollution

ASJC Scopus subject areas

  • Immunology


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