Background: Epidemiological studies in the past have focused on meteorological conditions, pollution and pollen and their relationship with symptoms of bronchial hyper-reactivity, however, there are no epidemiological studies which examine a wide range of such factors and determine their role in nasal hyper-reactivity.
Objective: To investigate whether environmental factors can influence symptomatology in non-allergic non-infectious perennial rhinitis (NANIPER) patients, who suffer primarily from nasal hyper-reactivity symptoms.
Methods: We studied 16 non-smoking NANIPER patients and seven non-smoking controls during a 218-day study period (March-October) by means of daily symptom scores and visual analogue scales for the subsets patency, secretions and sneezing, and compared them to seven primary factors which affected 'symptoms' and 10 secondary factors which affected primary factors only.
Results: The mean symptom scores in the NANIPER and control groups were 2.17 and 0.13, respectively. In NANIPER, the highest correlations of primary factors with symptomatology were found for symptom scores and sneezing with minimum daytime temperature (r = -0.62 and -0.45, respectively), ozone and NO concentrations. Patency and secretions were associated with minimum daytime temperature (r = -0.39 and 0.32, respectively). Time series analysis, however, correcting for several confounders such as autocorrelated symptomatology, showed that minimum daytime temperature and daytime relative humidity made an independent contribution to symptoms. In the control group, correlations were much lower, though present. Time series analysis was not possible.
Conclusions: We conclude that in a mild climate with relatively low levels of pollution, minor pollution and meteorological disturbances result in substantial changes in nasal reactivity symptoms in NANIPER patients, but not controls, irrespective of other factors such as allergy or infection.