Household dampness and microbial exposure related to allergy and respiratory health in Danish adults

Figures & data

Figure 1. Study design and selection of participants.

Table 1. Characteristics of the study population.

	Random sample		Atopics		Non-atopics
	n	(%)	n	(%)	n	(%)	p-value
Basic characteristics
Number of participants	196	(100)	107	(100)	99	(100)	-
Sex
Male	94	(48)	42	(40)	42	(42)	0.64^a
Female	102	(52)	65	(60)	57	(58)
Age (year), mean (SD)	54	(12.6)	42	(5.19)	44	(5.47)	0.21^b
20-29 years	7	(4)	0	(0)	0	(0)
30-39 years	18	(9)	32	(30)	26	(26)
40-49 years	49	(25)	75	(70)	73	(74)
50-59 years	43	(22)	0	(0)	0	(0)
60-69 years	59	(30)	0	(0)	0	(0)
>70 years	20	(10)	0	(0)	0	(0)
Home characteristics
Hours spend in the home, mean (SD)	14.6	(4.7)	12,8	(3.2)	13,1	(2.9)	0.59^b
Type of dwelling
Apartment	49	(25)	26	(24)	22	(22)	0.35^a
Detached house	107	(55)	62	(58)	61	(62)
Attached house/Rowhouse	39	(19)	18	(17)	15	(15)
Other type of dwelling	1	(1)	1	(1)	1	(1)
Indoor area (m^2)	126	(45.8)	122	(39.3)	137	(61.5)	0.04^b
<70 m^2	15	(8)	10	(10)	6	(6)	0.68^a
70-110 m^2	68	(35)	30	(28)	29	(30)
>110 m^2	113	(57)	68	(62)	64	(64)
Number of occupants	2,3	(1.01)	3,3	(1.25)	3,3	(1.18)	0.84^b
1	31	(16)	12	(11)	10	(10)	0.40^a
2	114	(58)	18	(18)	14	(14)
3	20	(10)	16	(15)	24	(25)
4	24	(12)	47	(44)	37	(38)
≥5	7	(4)	14	(12)	13	(13)
Crowding, mean (SD)	0.02	(0.01)	0,03	(0.01)	0,03	(0.01)	0.30^b
Pet keeping (yes)	62	(32)	48	(45)	55	(56)	0.12^a
Smoking, current (yes)	18	(9)	17	(16)	16	(16)	0.95^a
Daily	13	(7)	12	(11)	10	(10)	0.30^a
Occasionally	5	(3)	5	(5)	6	(6)
Ex-smoker	51	(26)	32	(30)	41	(41)
Never smoker	126	(64)	58	(55)	42	(42)
Dampness indicators
Damp stains in bedroom (yes)	12	(6)	12	(12)	8	(8)	0.45^a
Mould odor (yes)	5	(3)	9	(8)	2	(2)	0.38^a
Condensation on windows (yes)	48	(25)	43	(40)	34	(34)	0.04^a
Moisture damage, ever (yes)	47	(27)	23	(25)	27	(29)	0.85^a

Definition of abbreviations: n denotes number, SD denotes standard deviation. Statistical significance between atopics and non-atopics is denoted by a p-value <0.05.

^aChi²-test.

^bt-test.

Table 2. Allergy, asthma and lung function in the random sample, atopics and non-atopics.

	Random sample		Atopics		Non-atopics
	N = 196		N = 107		N = 99
	n	(%)	n	(%)	n	(%)	p-value
Allergy
SPT, any positive	64	(33)	107	(100)	0	(0)	0.00^a
Pollen	49	(25)	84	(78)	0	(0)	0.00^a
Pets	27	(14)	52	(48)	0	(0)	0.00^a
Molds	4	(2)	10	(9)	0	(0)	0.01^a
House dust mites	21	(11)	44	(41)	0	(0)	0.00^a
Rhinitis	33	(17)	57	(53)	5	(5)	0.00^a
Eczema	3	(2)	10	(9)	4	(4)	0.01^a
Asthma
Doctor-diagnosed asthma	14	(7)	21	(20)	10	(10)	0.02^a
Self-reported asthma	16	(8)	22	(21)	11	(11)	0.03^a
Asthma medication	8	(4)	9	(8)	4	(4)	0.92^a
Wheeze	19	(10)	24	(22)	10	(10)	0.01^a
Lung function
Observed
FEV1 (l), mean (SD)	3.08	0.82	3.37	0.69	3.45	0.82	0.01^b
FVC (l), mean (SD)	4.01	1.03	4.31	0.92	4.45	0.99	0.03^b
FEV1/FCV (%), mean (SD)	0.77	0.07	0.79	0.06	0.77	0.06	0.01^b
z-scores
zFEV1, mean (SD)	−0.34	0.94	−0.49	0.75	−0.37	0.99	0.03^b
zFVC, mean (SD)	−0.19	0.92	−0.28	0.75	−0.11	0.84	0.05^b
zFEV1/zFCV, mean (SD)	−0.31	0.95	−0.37	0.92	−0.48	0.97	0.81^b

Definition of abbreviations: n, number; SD, standard deviation; SPT, skin prick test (atopic sensitisation); FEV₁, forced expiratory volume in first sec.; FVC, forced vital capacity; zFEV₁, z-score for FEV₁; zFVC, z-score for FVC; zFEV₁/FVC, z-score for the ratio between FEV₁ and FVC. Statistical significance between atopics and non-atopics is denoted by p-value <0.05.

^aChi²-test.

^bt-test.

Table 3. Microbial detection in household dust by the random sample, atopics and non-atopics.

	Random sample			Atopics			Non-atopics			Difference between atopics and non-atopics	Difference between atopics and the random sample	Difference between non-atopics and the random sample
	% >LOD^a	GM	GSD	% >LOD^a	GM	GSD	% >LOD^a	GM	GSD	p-value^b	p-value^b	p-value^b
Microbial components
Endotoxin (10^3 EU/m^2)	92	0.21	5.29	64	0.04	9.16	91	0.05	3.70	0.61	0.00	0.00
β-(1,3)-D-glucan (µg/m^2)	92	3.55	3.37	87	3.87	4.02	-	-	-	-	0.62	-
Microorganisms (10^6 CE/m^2)
Streptomyces spp.	82	2.45	3.17	82	2.58	3,13	78	2.98	4.52	0.43	0.73	0.21
Acremonium strictum	5	0.24	1.78	13	0.26	1.70	17	0.32	2.59	0.03	0.45	<0.01
Alternaria alternata	24	0.11	2.70	41	0.15	2.95	37	0.15	3.49	0.98	0.06	0.06
Aspergillus fumigatus	24	0.66	2.23	38	0.81	2.51	51	1.42	4.59	<0.01	0.10	<0.01
Aspergillus versicolor	94	3.54	3.75	97	3.13	3.19	93	3.81	4.08	0.30	0.45	0.66
Aspergillus niger	6	0.11	3.12	4	0.09	2.72	10	0.09	4.49	0.87	0.35	0.43
Aspergillus glaucus spp.	26	0.22	2.57	28	0.23	2.42	32	0.25	2.67	0.59	0.82	0.41
Chaetommium globosum	8	0.05	1.86	6	0.05	1.61	11	0.06	2.49	0.06	0.64	0.09
Cladosporium cladosporioides	95	9.38	4.31	99	13.4	3.75	90	10.4	7.03	0.26	0.07	0.59
Cladosporium herbarum	96	18.8	6.30	100	23.1	4.87	96	30.6	8.75	0.29	0.37	0.04
Cladosporium sphaerospermum	67	1.94	3.86	60	1.51	3.52	75	3.59	5.34	<0.01	0.15	<0.01
Mucor/Rhizopus spp.	15	0.56	2.29	12	0.52	1.71	17	0.58	2.20	0.30	0.44	0.66
Penicillium/Aspergillus/Paecilomyces varioti spp.	99	37.3	3.84	99	27.0	3.31	100	40.0	3.61	0.04	0.04	0.67
Penicillium chrysogenum	14	0.17	1.81	15	0.18	1.79	27	0.23	2.31	0.02	0.75	<0.01
Rhizopus stolonifer	1	0.21	1.08	0	0.21	1.00	1	0.21	1.10	0.34	0.53	0.63
Stachybotrys chartarum/chlorohalonata	5	0.05	1.37	2	0.04	1.39	7	0.06	2.72	<0.01	0.71	<0.01
Trichoderma viride	12	0.18	2.21	13	0.19	2.65	14	0.19	2.31	0.88	0.56	0.68
Ulocladium chartarum	6	0.05	1.46	7	0.05	1.75	9	0.05	1.60	0.94	0.31	0.28
Wallemia sebi	42	0.94	3.07	43	0.97	3.10	40	1.00	3.41	0.82	0.85	0.66
Total fungi (10^8)	98	3.86	3.59	100	4.53	2.92	100	4.78	4.47	0.76	0.32	0.18
Diversity^c, mean (SD)	100	6.22	2.37	100	6.61	2.49	100	7.04	3.40	0.26	0.24	0.02

Definition of abbreviations: n, number; LOD, limit of detection; CE, cell equivalents; GM, geometric mean; GSD, geometric standard deviation; SD, standard deviation.

^aThe percentage denotes the proportion of samples above the detection limit of the specific microbe or microbial components (total number: (1) endotoxin and glucan assays (n/n, respectively): the random sample (196/150), atopics (107/100), non-atopics (99/-); (2) microorganisms: the random sample (n = 192), atopics (n = 98), non-atopics (n = 96). Samples below the LOD (limit of detection) were assigned half of the LOD value (endotoxin (4.5 EU/m²); β-(1,3)-D-glucan (0.18 µg/m²); LOD for microorganisms, please see table S1). The β-(1,3)-D-glucan assay was not performed in non-atopics.

^bt-test for differences in GM between microbial exposures in the different study groups. A p-value ≤0.05 in bold denotes a statistical significant difference between the atopis and non-atopics.

^cDiversity denotes the number of different microorganism groups detected (range; 3–14).

Figure 2. Associations of moisture damage with allergy, asthma and lung function in the random sample, atopics and non-atopics.

Figure 3. Associations of microbial diversity and total fungi with allergy, asthma and lung function in the random sample, atopics and non-atopics.