Studies in hay fever: Clinical observations including a botanical and air survey of the Utah region

Abstract

A study of the literature showed that the cause of hay fever varies widely in different sections of the country and that there is no uniformity in the atmospheric pollen concentration. It has been found, therefore, of increasing importance to make botanical surveys of the patients' environment, including the plant distribution and pollen production as well as the sensitivity of the patients. Many such studies have been made throughout the United States and Europe. Blackley's studies, published in 1873 and 1880, are outstanding pieces of research on hay fever. To Blackley belongs the credit for the method of pollen determination now still in use and also the method of cutaneous testing for the sensitivity of patients. Scheppegrell in 1917 devised a formula for the determination of the pollen content of the air, in grains per cubic yard, and this has been used by many investigators, but, because ragweed pollen is the chief cause of hay fever, practically all the reports thus far published have stressed the ragweed pollen content of the air. Since no reports were available regarding the wind-borne pollens of the Rocky Mountain region, I made botanical and air analysis studies in 1928, 1929, and 1930. Six test plots were chosen in which flora representative of the entire intermountain states was found; that is, alkali flat, desert, swamp, canyon, farming land, and high-grade residence property. From the results (Table I) it was evident that ragweed was neither the most abundant plant in the region nor the chief cause of hay fever as determined by cutaneous tests on hay fever patients. A total atmospheric pollen survey of Utah as a typical intermountain state was undertaken, therefore, rather than merely a ragweed survey. Pollen counting stations were established in four Utah towns. The results were graphed (Chart 1) and showed that the peaks of pollination fell in late July and early August when the grasses were beginning to wane and the weeds reached their maximum. Secondary peaks occurred in September when the sages pollinate. The total pollen production was estimated for the plants found (Table II). The most important anemophilous plants of this region proved to be as follows: (1) Graminaceae. (2) Chenopodiaceae—Russian thistle, salt bush, summer cypress. (3) Artemisia—sages. (4) Ambrosiaceae—ragweed. From cutaneous tests on 1,801 hay fever patients in this area, it was determined that 54.4 per cent of them reacted to the pollen of Russian thistle, 33.7 per cent to sagebrush and 31.4 per cent to common ragweed (Table III). The pollen abundance and the reactions of patients were compared, as below. PER CENT REACTING POLLEN RATING TO 2 PER CENT POLLEN EXTRACT Russian thistle 150 54.4 Sagebrush 130 33.7 Common ragweed 100 31.4 Timothy 40 26.4 Marsh elder 50 25.2 Blue grass 160 24.1 Box elder 35 21.1 Lambs quarter 20 19.1 A scratch reaction of 1:5,000 histamine was used as a positive control and no reactions from cutaneous scratch tests smaller than the histamine wheal were regarded as positive. Scrub oak was proved to have low toxicity. The box elder in spite of low abundance and pollen production accounted for 21.1 per cent of the patients. The fact that ragweed is not so important a factor in the hay fever of this region is due to its low distribution. The sensitivity tests on patients are shown in Table IV which demonstrates the high percentage of patients sensitive to more than one pollen and the low percentage of those whose hay fever is due to a single pollen. There is a considerably higher percentage sensitive to weed pollen than to tree or grass pollen, while nearly a third are sensitive to more than one group. In connection with this work an incidental study was carried on with regard to the effect of travel on hay fever symptoms. Pollen counts were made on vehicles of various types to determine the amount of pollen entrapped on petrolatum-coated slides. All counts were equated to a twenty-four-hour basis for purposes of comparison. Using the counts obtained in Salt Lake City as unity the following ratios for pollen concentration were obtained: Pullman coach 2.7 Chair car 3.8 Automobile 4.7 Electric train 6.2 Locomotive cab 7.2 Observation platform 8.0