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Epidemic of asthma possibly related to thunderstorms

BMJ 1994; 309 doi: (Published 09 July 1994) Cite this as: BMJ 1994;309:131

Rapid Response:

Thunderstorm-associated asthma in pollinosis patients

Thunderstorm-associated asthma in pollinosis patients


During a thunderstorm in Naples (Italy) on 4 June 2004 (between 1.30 and
2.00 am), six adults (three women and three men between 38 and 60 years
old) and a girl of 11 had attacks of severe bronchial asthma, which was
nearly fatal in one case. All patients received treatment in emergency
departments and one was admitted to an intensive care unit for very severe
bronchial obstruction and acute respiratory insufficiency.

All subjects were outdoors when the thunderstorm struck. The most severe
case, a 60-year-old woman sensitized only to Parietaria pollen allergens,
soon began to show symptoms of intense dyspnea which gradually worsened.
She was taken to hospital where she was intubated and given high
intravenous doses of corticosteroids. She was discharged a few days later.
She had previously suffered from seasonal asthma, but had been asthma-free
for the past few years and did not need continuous therapy. None of the
other six subjects regularly took antiallergic and/or antiasthma drugs.
Four had a history of asthma, whereas two had a history of only rhinitis.

We found that all seven patients had allergic respiratory symptoms upon
exposure to Parietaria, pollen, an Urticacea that is widespread in the
Naples area (1). Our seven cases were treated at the Fatebenefratelli and
Cardarelli hospitals. The latter is the largest hospital in southern Italy
and is the hospital of choice for local people. During the thunderstorm,
the concentration of airborne Parietaria pollen grains was particularly
high--a peak of 144 grains/m3 being recorded on June 3. Air pollution
levels were not particularly high on June 3 and 4. Based on the hourly
concentrations of nitric dioxide, ozone and respirable particulate matter
(PM10) measured at nine monitoring stations in Naples, we calculated the
mean and standard deviation for the two weeks before June 4 and the two
weeks after. The only values found to be slightly increased on June 4
versus the mean of the previous two weeks were those of N02 in two
stations and PM10 in one station; all other values were lower than the
mean. The two stations with increased values were in the suburbs, whereas
the patients were in the city centre at the start of the storm.

We contacted by telephone ten other subjects living in Naples who were
known to be sensitized to Parietaria who were indoors with the windows
closed during the night of 4 June, and none of them had experienced
respiratory symptoms.

The other thunderstorm-associated asthma outbreaks, which occurred in
London and Melbourne , also involved subjects sensitized to grass pollens
(2-5). There is evidence that thunderstorm-induced asthma is related to
the Parietaria pollen allergens. Pollen grains may, after rupture, release
part of their content, including respirable, allergen-carrying
paucimicronic particles . At the onset of a thunderstorm, pollen fragments
are carried to ground level where outflows distribute them. This results
in a high respirable allergen load in the air.

In the light of the above, subjects affected by pollen allergy should be
alert to the danger of being outdoors during a thunderstorm in the pollen

D'Amato, G. Liccardi, J.A.Gilder 1 S.Baldacci 2and G. Viegi2

Division of Pneumology and Allergology, Department of Chest Diseases, High
Speciality Hospital "Cardarelliâ", Naples, Italy;
1Scientific Communication, Naples,Italy; and 2Pulmonary Environmental Epidemiology Unit, CNR Institute of Clinical
Physiology, Pisa, Italy


1) D'Amato G, Liccardi G, D'Amato M, Cazzola M. Outdoor air pollution,
climatic changes and allergic bronchial asthma. Eur Res J 2002; 20: 763-

2) Packe GE, Ayres JG. Asthma outbreak during a thunderstorm. Lancet 1985;

3) Bellomo R, Gigliotti P, Treloar A, Holmes P, Suphioglu C, Singh MB.
Two consecutive thunderstorm associated epidemic of asthma in Melbourne.
Med J Aust 1992;156: 834-7.

4) Murray V, Venables K, Laing-Morton T, Partridge M, Williams D. Epidemic
of asthma possibly related to thunderstorms. Brit Med J 1994; 309: 131-2.

5) Antò J Sunyear J. Epidemic asthma and air pollution. In D'Amato G,
Holgate ST. The impact of air pollution on respiratory health. Monograph
of the European Respiratory Society, Sheffield, UK, 2002,pp.108-116.

Competing interests:
None declared

Editorial note
The six patients whose cases are described and the parent of the girl whose case is described have given their signed informed consent to publication.

Competing interests: No competing interests

07 January 2005
Gennaro D'Amato
MD,Director Division, Professor
Gennaro D'Amato, Gennaro Liccardi, Jean.Gilder Silvana Baldacci GiovanniViegi
Naples 80121 Italy