Table 1.

Lung histology in uninfected mouse lung tissue 72 h after intranasal instillation in vivo of either phosphate buffered saline (PBS) or ultrafine carbon black (2 × 500 μg).

Alveolar		Bronchiolar
PBS	Ultrafine-Carbon black	PBS	Ultrafine Carbon Black
Minimal diffuse alveolar microvascular congestion	Moderate to marked black particle inclusions - mainly within alveolar macrophages associated with moderate to marked secondary pneumonic reaction	Normal	Moderate sporadic black particle inclusions within bronchiolar epithelium
Minimal sporadic alveolar macrophage and neutrophil foci	Marked diffuse alveolar microvascular congestion		Marked multi-focal leucocyte infiltration of airway walls - mainly neutrophils and mononuclear cells
	Marked diffuse pneumonitis with consolidated microvascular leak		Moderate multi-focal hypertrophy of transitional airway epithelium
			Moderate to marked focal hypertrophy of mesothelium