Charles Harrison Blackley was a pioneer in allergy research. He carried out studies of hay fever, of which he himself was a sufferer. He was born at Bolton in 1820, and worked as a printer and engraver until he was thirty five years old. However, he qualified as a doctor in 1858, after studying at the Royal Manchester School of Medicine. He later received a M.D. from Brussels in 1874. Blackley practised as a homeopathist at Stretford Road, Manchester. He retired in 1894 and died in 1900 at Southport.
In 1859, Blackley began systematic researches into hay fever, and over the next fourteen years he studied all aspects of te phenomenon; his results were published as Experimental research on the causes and nature of Catarrus Aestivus (1873), with a second edition published in 1880, which included his ideas for treatment. The significance of Blackley's research was to identify grass pollen as the predominant cause of hay fever. He tested himself with over one hundred species of grass and flower, in fresh and dried states. the occurrence of pollen in a number of different localities. Blackley tested the effects on pollen in various ways: by applying it to the mucous membrane of the naries, by inhaling it, by applying it to the conjunctiva, applying fresh pollen to the mouth, and applying moistened pollen to the upper and lower limbs. By so doing, he showed that the nose was most susceptible to hay fever, but that inhalation of pollen would cease an asthmatic attack. He also maintained that immunity to hay fever was possible, as it symptoms were found to be least in the group with most exposure to pollen, farmers. Blackley is believed to have been the first to perform a skin test with pollen, and discovered that pollen applied to a skin abrasion caused a reaction. Blackley undertook further experiments measuring the amounts of pollen at different locations in town and country at different times of year; these were the first 'pollen counts'. By so doing, he was able to conclude that hay fever symptoms increased and diminished as amount of pollen in the atmosphere rose and fell. He was also able to show that the amount of pollen necessary to cause a reaction was small but definite.
Blackley also published works on lead poisoning, pernicious anaemia, cancer and on the action of drugs.