Methods to assess respiratory effects of complex mixtures.

This paper evaluates the influence of exposures on acute and chronic airway obstruction. Clinical, physiological, and immunological aspects are important in evaluating the effects of the pollutant exposures. Aspects of the exposure-response relationships important enough to record are those factors interactive with the pollutants (e.g., smoking and other personal/behavioral factors) and precursor conditions. To determine baseline status and study chronic effects, one uses standardized and modified health questionnaires and standardized pulmonary function. Confirmatory studies of responsive airways, potentially assessed first by diurnal peak flow, can be done using post-bronchodilator maximum expiratory flow volume curves and methacholine challenges. Immunoglobulin determinations for immunological status (a predisposing/susceptibility factor), allergy skin tests (for immediate hypersensitivity status), and blood counts (mostly for eosinophils) are also important. Other tests that could be performed include expired carbon monoxide and/or carboxyhemoglobin and methemoglobin (for smoking and combustion exposures). Measures of acute effects are symptomatic responses (by questionnaires and diaries), responses of the airways (as measured by spirometry and peak flows), and changes in medication usage or associated medical care (in diaries). Methodologies should also include discussions of protocols and analysis.