Various fractions of particulate matter have been associated with increased mortality and morbidity. The purpose of our study is to analyze the associations between concentrations of PM_2.5, PM_2.5–10, PM₁₀ and their chemical constituents (soluble ions) with hospital admissions due to circulatory and respiratory diseases among the elderly in a medium-sized city in Brazil. A time series study was conducted using Poisson regression with generalized additive models adjusted for confounders. Statistically significant associations were identified between PM₁₀ and PM_2.5–10 and respiratory diseases. Risks of hospitalization increased by 23.5% (95% CI: 13.5; 34.3) and 12.8% (95% CI: 6.0; 20.0) per 10 μg/m³ of PM_2.5-10 and PM₁₀, respectively. PM_2.5 exhibited a significant association with circulatory system diseases, with the risk of hospitalization increasing by 19.6% (95% CI: 6.4; 34.6) per 10 μg/m³. Regarding the chemical species; SO₄²⁻, NO₃⁻, NH₄⁺ and K⁺ exhibited specific patterns of risk, relative to the investigated outcomes. Overall, SO₄²⁻ in PM_2.5–10 and K⁺ in PM_2.5 were associated with increased risk of hospital admissions due to both types of diseases. The results agree with evidence indicating that the risks for different health outcomes vary in relation to the fractions and chemical composition of PM₁₀. Thus, PM₁₀ speciation studies may contribute to the establishment of more selective pollution control policies.

Nos centros urbanos o problema da mobilidade pública é um dos grandes desafios a ser enfrentado. Diante da complexidade das questões que norteiam o campo do transporte público, o artigo se propõe a fazer uma revisão crítica abordando alguns conceitos relacionados às causas e consequências, bem como uma breve abordagem quanto às possíveis soluções.