Although the ragweed season is almost over, the past several weeks have been particularly difficult for Washington residents sufferings from asthma - especially children.

As many as 27 youngsters in the throes of asthmatic attacks have been brought into the emergency room at Children's Hospital National Medical Center in a single 24-hour period.

While the hospital usually sees a daily average of about five such patients, the number now is varying between about one-dozen and two-dozen, said Dr. Michael Sly, chief of the hospital's allergy and immunology section.

These attacks, some of them life-threatening, are being caused by some of the same things that symbolize autumn for many non-asthmatics - leaves crunching under foot, the return of cool weather, wood smoke drifting from chimneys and long-dormant home heating systems shuddering back to life.

For asthmatics are particularly sensitive to any number of substances and atmospheric conditions that have little or no effect on the rest of us.

The seasonal drop in temperature, for instance, which is noticeable to all of us without being dangerous, can bring on intense suffering for asthmatics.

According to Sly, "it's not entirely known why, but the decreased temperature does cause wheezing."

The wheezing is caused by the narrowing of the asthmatic's air passages leading to and in the lungs. An attack may last anywhere from a few hours from simple wheezing to an inability to breath, loss of consciousness and even death.

The air passages constrict, and mucous builds up, when those passages come in contract with those things to which the asthmatic is sensitive, including pollens, dust and cold air. An attack may also be caused in some cases by strenuous exercise or emotional stress.

Autumn leaves are implicated in attacks because the microscopic mold pores found in the dead leaves can trigger the attacks. The same thing often is true of the smoke from wood fires so pleasurable to many of us.

And, as we experienced coller nights, and furnaces switch on, dust that can touch off attacks is sent cascading from heating ducts and vents.

Asthma patients often find themselves trapped between the furnace and the leaves. "If asmatics know they're sensitive to changes in temperature, or to some pollen or spores out of doors, they'd do best to stay in a protected environment as much as possible," Sly said.

"But if the patient is an asthmatic who's sensitive to dust, he might be better off out of doors," the physician continued.

In addition to worrying about dust, pollen and cold the asthmatics among cent of the population - are more troubled than most persons by upper us - and they number one to two per-resiratory infections, yet another cause of ashtma attacks.

Those suffering from severe asthma are, in fact, included on the list of "high risk" individuals for whom U.S. health officials have urged influenza immunization, for flu is one of those upper resiratory diseases that can touch off an attack.

Although the past few weeks have been a problem for children, physicians say they have not noticed any particular increase in asthmatic attacks in adults, a factor some find puzzling and others attribute to increased sensitivity in young asthmatics.

Whatever the problems now, the first snow should bring marked relief to the sufferers. Although colds and flu will be even more of a threat then, the snow will cover the moldy leaves and other forms of dust and pollen that are the primary natural enemies of asthmatics.