TABLE 1—

Main environmental factors having impact on lung defences

Type	Origin	Respiratory Effect	Lung defences
Ozone	Photochemical reaction from vehicle traffic	Lung function reduction	Antioxidant system
		Bronchial hyperresponsiveness	Permeability of epithelial cells
		Increased prevalence of respiratory symptoms	Inflammatory cytokines
		Increased hospitalisation	Mucociliary clearance
		Reduced exercise tolerance
Nitrogen dioxide	Gas combustion	Lung function reduction	Antioxidant system
	Vehicle traffic	Bronchial hyperresponsiveness	Inflammatory cytokines
		Increased prevalence of respiratory symptoms
		Reduced exercise tolerance
Particulate matter	Vehicle traffic	Lung function reduction	Antioxidant system
	Industrial activity	Increased prevalence of respiratory symptoms	Inflammatory cytokines
		Increased mortality from cardiorespiratory disease	Mucociliary clearance
Diesel exhaust		Bronchoconstrition	Antioxidant system
		Bronchial hyperresponsiveness	Inflammatory cytokines
		Airway inflammation	Macrophage phagocytosis
			Sensitisation
Sulphur dioxide	Fuel combustion from Industry	Lung function reduction	Antioxidant system
	Vehicle traffic	Increased prevalence of respiratory symptoms
		Increased mortality from respiratory disease