Air pollution in relation to allergic and nonallergic rhinitis

Objective: To investigate the relationship between allergic and nonallergic rhinitis and the exposure to air pollution. Design: Blood cadmium levels were measured in 30 patients with allergic rhinitis, 30 patients with nonallergic rhinitis, and 16 normal control subjects using atomic absorption spectrophotometry. The cadmium level was used as a parameter of degree and proximity of exposure to air pollution from various sources. Setting: Ain Shams University, a tertiary care referral tenter in Cairo, Egypt. Results: Blood cadmium levels were significantly high in the allergic rhinitis group compared with the nonallergic rhinitis and control groups (P<.001). The mean blood cadmium level in the nonallergic rhinitis group was higher than that in the controls, yet the difference was statistically insignificant. Also, cadmium levels were above the 95% confidence interval in only 7% of this group. Blood cadmium levels in the controls (16.33+2.98 [SD] pmol/L [183.62+/-33.5 mu g/dL]) were much higher than those reported from areas of high cadmium pollution (0.88-2.66 mu mol/L [10-30 mu g/dL]). Conclusion: The significantly high blood cadmium levels in patients with allergic rhinitis may reflect a causal relationship between air pollution and this condition. The exact mechanism, however, remains to be determined. In nonallergic rhinitis, it seems that the contribution of air pollution as a predisposing factor is small compared with the other known predisposing factors.