Subjects with seasonal allergic rhinitis and nonrhinitic subjects react differentially to nasal provocation with chlorine gas.

BACKGROUND

Nasal irritation and associated symptoms (nasal congestion, rhinorrhea, and sinus headache) are important elements of the response to indoor and outdoor air pollution. Marked interindividual variability in such symptoms has been suggested clinically and epidemiologically, but little experimental data exist on this issue.

OBJECTIVE

We sought to test the hypothesis that subjects with seasonal allergic rhinitis (SAR) exhibit a more marked physiologic response (congestion) after nasal irritant provocation than do nonrhinitic subjects.

METHODS

We studied eight subjects with SAR and eight nonrhinitic subjects; subjects with SAR were studied out of season. In a single-blind crossover study, subjects had their nasal airway resistance (NAR) measured in triplicate before, immediately after, and 15 minutes after a 15-minute exposure to either filtered air or 0.5 ppm chlorine in filtered air, administered through a nasal mask in a climate-controlled chamber. Log-transformed NAR values were analyzed in a repeated-measures analysis of variance model, with confirmatory testing using paired t tests.

RESULTS

The net (chlorine minus air day) percent change in NAR from baseline (before exposure) to immediately after exposure was +24% in the SAR group and +3% in the nonrhinitic group (p < 0.05). The corresponding net changes from baseline to 15 minutes after exposure were +21% in the SAR group and -1% in the nonrhinitic group (p < 0.05).

CONCLUSIONS

The observed augmented nasal congestive response of subjects with SAR versus nonrhinitic subjects to a controlled low-level chemical irritant provocation is consistent with epidemiologic surveys showing a higher prevalence of nasal symptoms among subjects with SAR than nonrhinitic subjects in environments involving irritant air pollutants.