Table 1

Correlation estimates between exacerbations-related COPD admissions and the variables of interest

Variables (weekly)	N	Correlation estimate	P Value
COPD admission (a week ago)	100	0.91	<0.0001
COPD admission (2 weeks ago)	100	0.81	<0.0001
Stringency Index (SI)	100	−0.80	<0.0001
COVID-19 case	100	−0.43	<0.0001
COVID-19 admission	100	−0.54	<0.0001
COVID-19 death	100	−0.47	<0.0001
Temperature	100	−0.07	0.52
Nitric oxide (NO)*	100	0.60	<0.0001
Nitrogen dioxide (NO2)*	100	0.58	<0.0001
Oxides of nitrogen (NOX)*	100	0.61	<0.0001
Sulphur dioxide (SO2)^†	100	0.09	0.403
Ozone (O3)^†	100	−0.21	0.036
PM10^†	100	0.13	0.205
PM2.5^†	100	0.16	0.145

Note: Air quality monitoring stations in Camden: *Holborn, ^†Bloomsbury.
COPD, chronic obstructive pulmonary disease; PM, particulate matter.