Face masks ease allergies by 'lowering the burden' of inhaled pollen, spores and dust, study suggests

From supermarkets to buses, donning a face covering in public enclosed spaces has become many people's "new normal".

While some find the masks uncomfortable, studies suggest they help stem the coronavirus' spread, with new research also implying they could have an unexpected benefit for allergy sufferers.

During Israel's 2020 spring, medics from the Galilee Medical Center and Bar-Ilan university sent a questionnaire to more than 1,800 nurses who wore masks during their eight to 12 hour shifts.

Results reveal the coverings significantly eased some of the allergy sufferers' cold-like symptoms when worn for as little as one week.

Read more: 10% rise in mask-wearing triples chance of coronavirus' R being below one

While not a perfect solution, face masks may "lower the burden" of inhaled allergens, like pollen, dust mites and fungal spores.

"With so many people wearing masks outdoors this year, we've seen patients reporting fewer seasonal allergy issues," said Professor John Leung from Tufts University in Massachusetts, who was not involved in the research.

"We saw an increase in indoor allergies as people added dogs or cats to their household and spent more time at home.

"Our houses are the one place most people aren't wearing a mask, and more patients are seeking treatment for allergies to animals, dust, and mould."

Read more: Wash face coverings every day at 60C to ward off coronavirus

More than one in five (20%) people in the UK has at least one allergy, with hay fever alone affecting up to 30% of adults.

A recent Swiss study suggests the problem is set to worsen, with pollen seasons beginning earlier and becoming more intense over the past 30 years due to climate change.

Watch: How to wear a face covering comfortably

In the Israeli study, the nurses worked on respiratory wards or departments dedicated to coronavirus patients.

They were sent the survey on 5 April, 2020, "during the early spring in Israel where seasonal allergens are widely dispersed", the medics wrote in The Journal of Allergy and Clinical Immunology.

Of the more than 1,800 nurses, 233 had "intermittent" allergic rhinitis; defined as inflammation of the inner nostrils that leads to sneezing, itchiness and congestion. For 68 of the participants, the symptoms were "persistent".

The nurses scored their symptoms before and after wearing face masks over several weeks at work.

Among the 215 allergy sufferers who wore two types of masks – surgical and N95 respirators – for one week each, the proportion reporting mild symptoms fell from 42% to 29% with the surgical mask and 25% with the N95, compared to no covering at all.

The US Food and Drug Administration defines N95s as "a respiratory protective device designed to achieve a very close facial fit and very efficient filtration of airborne particles".

Read more: Pfizer coronavirus jab causes severe allergic reaction in under 1% of cases

Severe symptoms also declined from 20% to 13% with the surgical mask and 12% with the N95.

The 47 nurses who just wore a surgical mask saw a "marked improvement" when it came to mild symptoms, but not more severe discomfort.

The reverse was true for those who only donned a N95; improved severe symptoms but not mild.

Of the overall 301 allergy sufferers, those with persistent symptoms did not benefit from any mask.

Those with intermittent discomfort had a "demonstrable improvement", but not when it came to eye-specific symptoms, with this part of the face still being exposed despite a mask.

Watch: How to remove a face covering

Pollen typically measures from 0.01mm to 0.1mm, while other allergens like fungal spores and dust mite faeces range from 0.002mm to 0.05mm and 0.01mm to 0.04mm, respectively.

Surgical masks can filter out particles larger than 0.003mm, while N95s block substances as small as 0.00004mm.

The latter was not markedly more effective than surgical masks, however, "potentially attributable to unfiltered airflow through imperfect mask seal edges or allergen exposure when not wearing personal protective equipment".

N95s also tend to be made of denser fabric, which can make breathing laboured. This may affect the pressure within the mask, triggering "face seal leakage".

Professor Leung expects even homemade face coverings to offer some benefit, "especially those with multiple layers of fabric".

Overall, any covering has "obvious physical filtration properties", but may also ease allergies by "altering the humidity and temperature of breathed air".

The allergens that are inhaled despite the mask may then cause milder symptoms, according to the medics.

They acknowledged Israel's lockdown at the time of the study may have also eased the nurses' symptoms somewhat, despite them still going to work.

While further research is required, the team concluded: "Our results reveal face mask usage may reduce allergic rhinitis symptom severity in chronically affected individuals with intermittent disease.

"Mask utilisation based on personal allergen profiles can be considered a preventive measure to minimise exposure of the respiratory system to provocative allergens in high-risk environments."

Professor Leung pointed out masks can make eczema, which often occurs alongside allergies, worse.