Table 3.

Average ambient relative humidity and temperature and total airborne influenza A virus concentration in each of 16 samples. Humidity and temperature were recorded every 2 min, and each sample was collected using a cascade impactor for 6–8 h. IAV RNA was extracted from filters and quantified by qRT–PCR. It was not detected in half of the samples. In the samples containing detectable amounts of IAV, the average concentration was 1.6 ± 0.9 × 10⁴ genome copies m⁻³.

date	location	RH (%)		temperature (°C)		total IAV concentration (genome copies m−3)
		mean	s.d.	mean	s.d.	mean	s.d.
10 Dec 2009	health centre	16.98	1.71	21.17	0.25	1.6 × 104	1.2 × 104
17 Dec 2009	day-care	42.93	2.85	20.71	0.36	1.6 × 104	1.0 × 104
30 Dec 2009	aeroplane	n.a.a	n.a.	n.a.	n.a.	n.d.b	n.d.
26 Jan 2010	health centre	21.72	0.89	20.75	0.54	n.d.	n.d.
27 Jan 2010	day-care	32.93	2.03	25.12	1.06	3.7 × 104	2.0 × 103
9 Feb 2010	health centre	25.15	0.80	20.86	0.56	5.8 × 103	6.2 × 102
11 Feb 2010	health centre	18.77	1.13	20.51	0.68	n.d.	n.d.
22 Mar 2010	aeroplane	29.25	13.86	25.11	3.47	1.4 × 104	1.0 × 103
24 Mar 2010	aeroplane	25.06	8.69	21.85	1.37	1.1 × 104	1.1 × 103
30 Mar 2010	health centre	29.81	4.83	22.16	0.85	n.d.	n.d.
31 Mar 2010	day-care	43.61	1.58	21.82	0.85	1.6 × 104	1.1 × 102
6 Apr 2010	health centre	54.66	5.00	23.15	0.75	1.5 × 104	1.7 × 103
8 Apr 2010	health centre	49.33	1.15	22.71	0.37	n.d.	n.d.
9 Apr 2010	day-care	52.12	0.82	22.02	1.01	n.d.	n.d.
20 Apr 2010	health centre	31.70	1.07	21.84	0.86	n.d.	n.d.
22 Apr 2010	health centre	32.53	2.29	21.91	0.75	n.d.	n.d.

^aNot available owing to a logging error.

^bNo detectable influenza A virus genome.