Study gives more proof of 'thunderstorm asthma'

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Study gives more proof of 'thunderstorm asthma' Last Updated: 2003-

03-13 17:00:31 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Asthmatics who believe that their

symptoms get worse during thunderstorms may be right, according to

the results of a six-year study.

It also suggests that the reason for so-called thunderstorm asthma

may have something to do with the increased concentration of

airborne fungal spores during thunderstorms, rather than the high

grass pollen counts, as has been suggested previously.

Over the past 20 years, there have been sporadic reports linking

worsened asthma with thunderstorms. The phenomenon has been observed

in Australia, London and the United States, but it has not

previously been studied in depth.

In the current study, Dr. E. Dales of the University of

Ottawa Health Research Institute in Ontario, Canada, and his

colleagues conducted daily observations of thunderstorms and

children's asthma-related emergency department visits over a six-

year period.

They found that asthma-related hospital visits increased by 15

percent during thunderstorms, from an average 8.6 visits on days

without thunderstorms to 10 on stormy days.

The findings appear in the March issue of the journal CHEST.

The investigators also observed a near doubling in the concentration

of allergens called fungal spores during thunderstorms.

Overall, although fungal spores were more abundant in the summer

months of July, August and September than in the spring, they were

always most plentiful during thunderstorms, regardless of the

season.

Previous studies have suggested that asthma exacerbations during

thunderstorms are somehow caused by the higher pollen counts. But

Dales and his team found no association between hospital visits and

weed, grass or tree pollen.

Yet the researchers did find a link between increased fungal spores

and asthma-related hospital visits, even in the absence of

thunderstorms.

As the fungal spore count rose from day to day, so too did the

number of asthma-related emergency department visits, " making it

unlikely that the elevations in spores and asthma were simply

coincidental, " the authors write.

They note, however, that their study was concentrated in one

geographic area (Ottawa), so it's unclear if the findings hold true

in other climates.

A previous study showed asthma attacks may also be more common on

misty or foggy nights.

CHEST 2003;123:745-750.