Relationship between particulate matter less than 10 µm in diameter (PM₁₀) exposure and proprotein convertase subtilisin/kexin type 9 (PCSK9) circulating levels. (a) shows the effect of average annual PM₁₀ exposure on circulating PCSK9 levels as assessed by univariate analysis (β = 1.83, standard error (SE) = 0.75, p = 0.0144). (b) depicts the relationship between six-month PM₁₀ exposure and PCSK9 circulating levels (β = 0.734, SE = 0.302, p-value 0.0156; Figure 1(b)) as assessed by univariate model.