Environmental triggers and avoidance in the management of asthma

Figures & data

Table 1 Self-reported asthma triggers as ranked by the proportion of participants who have experienced the trigger and by how frequently the trigger was reported

Triggers	Percentage of participants who have ever experienced, n=1202	Triggers	Frequency (weeks/year), n=1202
Dust or dusting	72	Dust or dusting	18.6
Cold, flu, infections, and sinusitis	6	Smoking (eg, cigarettes or cigars)	14.2
Coughing	68	Coughing	11.3
Smoking (eg, cigarettes or cigars)	60	Exercise	11.1
Smoke	59	Vacuum cleaning	10.1
Smog and air pollution	58	Perfumes, hairspray, or air fresheners	10.0
Exercise	54	Animals	9.6
Strong odors	54	Smog and air pollution	9.5
Weather changes	51	Smoke	9.0
Mold and mold spores	51	Emotions	8.2
Animals	50	Cleaning products	8.2
Damp places	48	Damp places	8.1
Humidity	48	Weather changes	8.0
Perfumes, hairspray, or air fresheners	48	Humidity	7.9
Grass, mowing the lawn, and weeds	47	Strong odors	7.6
Cold air	45	Mold and mold spores	7.4
Emotions	43	Cold air	7.2
Cleaning products	42	Grass, mowing the lawn, and weeds	6.9
Vacuum cleaning	41	Lying flat	6.8
Feathers	40	Cold, flu, infections, and sinusitis	6.7
Air conditioning	37	Air conditioning	5.8
Lying flat	29	Feathers	5.4
Your work environment	25	Your work environment	4.8
Rain	19	Rain	3.4
Food and drinks of food colorings	19	Food and drinks of food colorings	3.1
Alcohol	18	Indigestion or heartburn	2.8
Other medications	18	Alcohol	2.4
Indigestion or heartburn	17	Aspirin	2.1
Eating out at particular restaurants	15	Other medications	2.0
Aspirin	15	Eating out at particular restaurants	1.8
Hormonal changes	14	Hormonal changes	1.8
Paracetamol	12	Paracetamol	1.6

Note: Adapted from Price D, Dale P, Elder E, Chapman KR. Types, frequency and impact of asthma triggers on patients’ lives: a quantitative study in five European countries. J Asthma. 2014;51(2):127–135. © 2014 The Author(s). Published by Taylor & Francis.¹

Table 2 Practical measures for reducing dust mite and pet allergen levels: effect on allergen levels and the clinical effect on symptoms of rhinitis and asthma

Measure	Effect on allergen levels	Clinical effectiveness
House dust mite allergen avoidance
Encasing mattresses, pillows, and quilts in impermeable covers	Ib	Ia – no effect in adults Ib – some effect in children
Washing bedding in the hot cycle (55°C–60°C)	IIb	IV
Replacing carpets with hard flooring	Ib	IV
Acaricides and/or tannic acid	III	IV
Minimizing dust accumulating objects in closed cupboards	IV	IV
Vacuum cleaners with integral HEPA filter and double thickness bags	IIb	IV
Removing and hot washing/freezing of soft toys	IV	IV
Pet allergen avoidance
Removing cat/dog from the home	IIb	IV
Keeping the pet out of the main living areas and bedrooms	IIb	IV
HEPA filter air cleaners	Ib	Ia – no effect in pet allergy
Washing a pet	IIb	IV
Replace carpets with linoleum or wood flooring	IV	IV
Vacuum cleaners with integral HEPA filter and double thickness bags	IV	IV

Notes: Evidence level graded according to the Scottish Intercollegiate Guidelines Network recommendations: Ia, evidence obtained from meta-analysis of randomized controlled trials; Ib, evidence obtained from at least one randomized controlled trials; IIb, evidence obtained from at least one other type of well-designed quasiexperimental study; III, evidence obtained from well-designed nonexperimental descriptive studies, such as comparative studies, correlation studies, and case studies; IV, evidence obtained from expert committee reports or opinions and/or clinical experience of respected authorities. Reproduced from Custovic A, Wijk PG. The effectiveness of measures to change the indoor environment in the treatment of allergic rhinitis and asthma: ARIA update (in collaboration with GA(2)LEN). Allergy. 2005;60(9):1112–1115. Copyright © Blackwell Munksgaard 2005.⁷

Abbreviation: HEPA, High efficiency particulate arrestance.

Table 3 Fungal components and products relevant for indoor air sciences

Fungal agent	Short description	Applications in indoor air research
Fragments	Particles of fungal origin that are smaller than whole spores (typically <1 μm)	May have relevance as exposure agents related to health effects
Ergosterol	Sterol specific to fungal cells Present in most fungal cells, underrepresented in yeasts No specific role as health-relevant agent	Ergosterol content used as a proxy for fungal biomass
Glucans	Major structural component of fungal cells (1–3)- and (1–6)-linked polymers of d-glucose Nonallergenic but possess proinflammatory properties	Glucans’ content is used as a proxy of bioactive portion of fungal biomass
EPS	Stable, high molecular weight sugar polymers on the surface of fungal cells, produced during growth	Marker of fungal biomass (mainly Penicillium and Aspergillus) No longer widely used
Fungal allergens	Antigenic substances of fungi capable of stimulating an IgE-mediated response	Indoor exposure and role in health effects insufficiently known
MVOC	Highly volatile low molecular weight chemicals, produced by growing fungi (and bacteria) as primary and secondary metabolites Include alcohols, aldehydes, amines, ketones, terpenes, and aromatic hydrocarbons Relatively low toxicity	Recognized as odor of mold Measurement of MVOCs is not a good indicator of fungal growth as there are very few VOCs specific to microbial sources only
Mycotoxins	Nonvolatile fungal secondary metabolites with a variety of chemical structures Chemically stable and some of them are thermally stable Many are bioactive and some are acutely toxic by ingestion May be present airborne attached to other particles	Occurrence in indoor air has been shown Role as causative agents of symptoms possibly due to their toxicity and inflammatory potential Specific studies on their connection to health still lacking
Fungal nucleic acids DNA and RNA	Polymeric macromolecules composed of nucleotides Contains the genetic material of a fungal cell (DNA) or acts in converting the genetic information (RNA) Located in the different cellular organelles and the mycoplasm	No relevance as a potential causative agent of health outcomes Widely used as a target in DNA-based methods that are increasingly applied in indoor air research (including quantitative PCR, DNA fingerprinting, and sequencing applications)

Note: Reproduced from Nevalainen A, Täubel M, Hyvärinen A. Indoor fungi: companions and contaminants. Indoor Air. 2015;25(2):125–156. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.¹⁰

Abbreviations: EPS, extracellular polysaccharides; IgE, immunoglobulin E; MVOC, microbial volatile organic compounds.

Table 4 Association between excessive humidity/molds and health impact according to the IOM, the WHO, and the ANSES

Health authorities	IOM^Citation18	WHO^Citation20	ANSES^Citation19
Bronchial symptoms (cough and wheezing)	+	+	+
Asthma occurrence	0	0	+ children + occupational asthma in adults
Asthma exacerbations	+	+	+
Hypersensitivity pneumonia	+	+	+

Note: “+” means the association has been acknowledged, and “0” means that it has not.

Abbreviations: ANSES, French Agency for Food, Environment and Occupational Health & Safety; IOM, Institute of Medicine of the National Academies; WHO, World Health Organization.

PriceDDalePElderEChapmanKRTypes, frequency and impact of asthma triggers on patients’ lives: a quantitative study in five European countriesJ Asthma201451212713524050523

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