\begin{tabular}{llrrrr}
\toprule
Specification & Outcome & $\chi^2$ & df & $p$ & Holm $p$ \\
\midrule
Baseline & NO$_2$ & 3.34 & 3 & 0.342 & 1.000 \\
Baseline & CO & 2.28 & 3 & 0.517 & 1.000 \\
Baseline & SO$_2$ & 27.72 & 3 & $<0.001$ & $<0.001$ \\
Baseline & O$_3$ & 25.68 & 3 & $<0.001$ & $<0.001$ \\
Baseline & PM$_{10}$ & 3.95 & 3 & 0.266 & 1.000 \\
\midrule
Cohort trends & NO$_2$ & 4.93 & 3 & 0.177 & 1.000 \\
Cohort trends & CO & 5.22 & 3 & 0.156 & 1.000 \\
Cohort trends & SO$_2$ & 3.14 & 3 & 0.370 & 1.000 \\
Cohort trends & O$_3$ & 4.89 & 3 & 0.180 & 1.000 \\
Cohort trends & PM$_{10}$ & 1.59 & 3 & 0.662 & 1.000 \\
\bottomrule
\end{tabular}