Repeated nitrogen dioxide exposures and eosinophilic airway inflammation in asthmatics: a randomized crossover study.

BACKGROUND: Nitrogen dioxide (NO2), a ubiquitous atmospheric pollutant, may enhance the asthmatic response to allergens through eosinophilic activation in the airways. However, the effect of NO2 on inflammation without allergen exposure is poorly studied. OBJECTIVES: We investigated whether repeated peaks of NO2, at various realistic concentrations, induce changes in airway inflammation in asthmatics. METHODS: Nineteen nonsmokers with asthma were exposed at rest in a double-blind, crossover study, in randomized order, to 200 ppb NO2, 600 ppb NO2, or clean air once for 30 min on day 1 and twice for 30 min on day 2. The three series of exposures were separated by 2 weeks. The inflammatory response in sputum was measured 6 hr (day 1), 32 hr (day 2), and 48 hr (day 3) after the first exposure, and compared with baseline values measured twice 10-30 days before the first exposure. RESULTS: Compared with baseline measurements, the percentage of eosinophils in sputum increased by 57% after exposure to 600 ppb NO2 (p = 0.003) but did not change significantly after exposure to 200 ppb. The slope of the association between the percentage of eosinophils and NO2 exposure level was significant (p = 0.04). Eosinophil cationic protein in sputum was highly correlated with eosinophil count and increased significantly after exposure to 600 ppb NO2 (p = 0.001). Lung function, which was assessed daily, was not affected by NO2 exposure. CONCLUSIONS: We observed that repeated peak exposures of NO2 performed without allergen exposure were associated with airway eosinophilic inflammation in asthmatics in a dose-related manner.

Effect of formaldehyde on asthmatic response to inhaled allergen challenge.

BACKGROUND: Exposure to formaldehyde may lead to exacerbation of asthma. OBJECTIVES: Our aim in this study was to investigate whether exposure to a low level (500 microg/m(3)) of formaldehyde enhances inhaled allergen responses. METHODS: Twelve subjects with intermittent asthma and allergy to pollen were exposed, at rest, in a double-blind crossover study to either formaldehyde or purified air for 60 min. The order of exposure to formaldehyde and air-only was randomized, and exposures were separated by 2 weeks. We also performed an allergen inhalation challenge after each exposure. Airway responsiveness to methacholine and lower airway inflammation (induced sputum) were assessed 8 hr after allergen challenge. RESULTS: The median dose of allergen producing a 15% decrease in forced expiratory volume in 1 sec (PD(15)FEV(1)) was 0.80 IR (index of reactivity) after formaldehyde exposure compared with 0.25 IR after air-only exposure (p = 0.06). Formaldehyde exposure did not affect allergen-induced increase in responsiveness to methacholine (p = 0.42). We found no formaldehyde-associated effect on the airway inflammatory response, in particular the eosinophilic inflammatory response, induced by the allergen challenge 8 hr before. CONCLUSION: In this study, exposure to 500 microg/m(3) formaldehyde had no significant deleterious effect on airway allergen responsiveness of patients with intermittent asthma; we found a trend toward a protective effect.

[The sick building syndrome (SBS)]. / Le sick building syndrome (SBS) ou syndrome des bâtiments malsains.

AN INCREASINGLY COMMON ENVIRONMENTAL HEALTH PROBLEM: Complaints related to indoor environment represent one of the most frequent problems that environmental health practitioners are confronted with. Hence the incidence of the Sick Building Syndrome (SBS) has been increasing since the Seventies. DIFFERING DEFINITIONS AND CLINICAL PRESENTATIONS: The WHO defines SBS as an excess of complaints and symptoms occurring in certain occupants of non-industrial buildings. The syndrome can only be evoked after elimination in the person concerned of a disease related to the building, the aetiological agent of which is identifiable. The symptoms described during SBS (headaches, concentration problems, asthenia, irritation of the skin or nasal mucosa, of the eyes and upper respiratory tract.) are non specific and frequently observed in the general population. AN UNKNOWN CASE, BUT NUMEROUS AETIOLOGICAL FACTORS SUSPECTED: There is no unanimously accepted definition nor physio-pathological theory to explain the occurrence of SBS in a particular building. Many favouring factors, including the type and rate of ventilation, volatile organic compounds, particles and humidity have been suspected. TECHNICAL, SOCIAL, AND MEDICAL MANAGEMENT IS REQUIRED: Although the symptoms are benign, they can be uncomfortable or even handicapping and prevent the functioning of workplaces. The SBS, the social and economical costs of which are high, requires multidisciplinary management.