Table 1.

Associations of precipitation, temperature, pressure, and pollutants with asthma-related ED visits ($N=\mathrm{62,438}$) for days with ($N=\mathrm{15,179}$) or without thunderstorms ($N=\mathrm{53,621}$) in Louisiana, 2010–2012.

Daily climate and pollutant variables (unit)	Full model RR (95% CI): thunderstorm		Reduced model RR (95% CI): thunderstorm		Full model RR (95% CI): non-thunderstorm	Reduced models RR (95% CI): non-thunderstorm
	Same day visits ($N=\mathrm{12,415}$)	Next day visits ($N=\mathrm{6,808}$)	Same day visits ($N=\mathrm{12,415}$)	Next day visits ($N=\mathrm{6,808}$)	Same day visits ($N=\mathrm{50,023}$)
Precipitation rate ($1{\mathrm{g}/\mathrm{m}}^2/\mathrm{s}$)	1.128 (0.992, 1.284)	0.938 (0.779, 1.130)	1.145 (1.009, 1.300)	0.996 (0.831, 1.193)	1.044 (0.921, 1.184)	1.022 (0.903, 0.158)
Temperature drop (1 °C)	1.010 (1.000, 1.021)	1.007 (0.994, 1.019)	1.011 (1.000, 1.021)	1.008 (0.996, 1.020)	1.001 (0.998, 1.004)	1.001 (0.998, 1.004)
Pressure (1 kPa)	1.010 (0.946, 1.078)	1.004 (0.930, 1.084)	1.010 (0.946, 1.078)	1.012 (0.938, 1.093)	0.995 (0.971, 1.019)	0.997 (0.973, 1.020)
${\mathrm{O}}_3$ (1 ppb)	1.001 (0.998, 1.003)	1.001 (0.997, 1.004)	—	—	1.002 (1.001, 1.003)	—
${\mathrm{PM}}_{2.5}$ ($1{\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$)	0.995 (0.990, 1.003)	0.986 (0.977, 0.996)	—	—	0.99 (0.996, 1.002)	—

Note: Time-series quasi-Poisson regression models were adjusted for long-term trend with natural cubic spline ($\text{degrees of freedom}=36$), parish, Louisiana holidays, day of week, and season (summer vs. non-summer); next day ED visit models analyzed to evaluate associations of precipitation or temperature of the thunderstorm day with the next non-thunderstorm day’s asthma-related ED visits; 1,351 ED visits were deleted from the regression analyses owing to missingness in lightning data. —, variables not included in the reduced models; CI, confidence interval; ED, emergency department; ${\mathrm{O}}_3$, ozone; ${\mathrm{PM}}_{2.5}$, particulate matter $\le 2.5\mathrm{\mu }\mathrm{m}$ in aerodynamic diameter (fine particulate matter); RR, relative risk.