Respiratory toxicity of repeated exposure to particles produced by traffic and sugar cane burning

- Prolonged exposure to either traffic or biomass particles impaired lung mechanics.
- Lung parenchyma of mice exposed to pollution showed a larger amount of macrophages.
- Lung parenchyma and bronchial integrity were more injured by biomass particles.
- Alveolar collapse was greater after exposure to biomass than to urban particles.
- Biomass particles struck the lung more than urban material in a long-term exposure.

We compared the toxicity of subchronic exposure to equivalent masses of particles from sugar cane burning and traffic. BALB/c mice received 3 intranasal instillations/week during 1, 2 or 4 weeks of either distilled water (C1, C2, C4) or particles (15 μg) from traffic (UP1, UP2, UP4) or biomass burning (BP1, BP2, BP4). Lung mechanics, histology and oxidative stress were analyzed 24 h after the last instillation. In all instances UP and BP groups presented worse pulmonary elastance, airway and tissue resistance, alveolar collapse, bronchoconstriction and macrophage influx into the lungs than controls. UP4, BP2 and BP4 presented more alveolar collapse than UP1 and BP1, respectively. UP and BP had worse bronchial and alveolar lesion scores than their controls; BP4 had greater bronchial lesion scores than UP4. Catalase was higher in UP4 and BP4 than in C4. In conclusion, biomass particles were more toxic than those from traffic after repeated exposures.