Table 1. Six hypothetical laboratories and their metered dose inhaler-associated carbon footprint and medication cost, per 100 BDR tests.

	A	B	C	D	E	F
Laboratory practice
Actuations per BDR test	2	4	4	12	4	4
Reuse of MDIs	Yes	Yes	Yes	Yes	No	No
Disposal	Incineration	Incineration	Landfill	Landfill	Incineration	Landfill
Consumption (per 100 BDR tests)
MDIs	1	2	2	6	100	100
Actuations	200	400	400	1200	400	400
Medication cost (per 100 BDR tests)
$A	$A6.5	$A13	$A13	$A39	$A650	$A650
Carbon footprint in kg CO2e (per 100 BDR tests)
Manufacture	1	2	2	6	100	100
Patient use	25.3	50.7	50.7	152	50.7	50.7
Disposal (propellant)	<0.001	<0.001	2.66	7.98	0.26	2607
Disposal (other)	0.015	0.030	0	0	2.9	0
Total kg, CO2e	26.3	52.7	55.4	166	154	2758

The colours in the above table indicate the carbon footprint associated with that particular laboratory practice. Actions with the lowest carbon footprint have green shading, actions with the highest carbon footprint have red shading, while orange indicates an intermediate carbon footprint.

$A, Australian dollars; BDR, bronchodilator responsiveness; CO2e, carbon dioxide equivalent; MDI, metered dose inhaler