Durham Sampler

It was designed by Oren C. Durham in 1946, who was for many years Head Botanist at the Abbott Laboratories. Durham's sampler was adopted as the standard pollen sampler by the Pollen and Mold Committee of the American Academy of Allergy. It is still used sometimes by allergists, hospitals, and public health agencies on account of its easy availability.

The Durham sampler consists of a mount for positioning a glass microscope slide holder between two horizontal circular metallic disks. It is usually mounted on a metal rod, pipe or steel angle support at least several feet above the ground or on a roof top to have free flow of air all around (Fig. 13.2).

The advantages of the Durham Sampler are:

1) The slides are easily loaded.

2) It is inexpensive.

3) It has no moving parts.

4) It requires no electric power supply.

Durham Pollen Trap

Disadvantages are:

1) The volume of air sampled is unknown, so the catch cannot be converted to a volumetric measure of concentration.

2) The efficiency cannot be determined.

3) The catch is relatively low.

4) The catch is a function of wind speed, turbulence and orientation of the sampler with respect to wind direction as well as concentration of pollen in the air.

Several attempts have been made to improve the sampler. Some workers have tilted slide samplers at a 45° angle in attempts to collect by both impaction and settling. However, none of these modifications appears to be a significant improvement over the original sampler.

Counts from the Durham Sampler are so greatly influenced by factors other than the concentration of pollen in the air that they indicate only in a general way the presence and abundance of pollen in the atmosphere. Tests have shown that it is impossible to determine the volume of air sampled; therefore, the data are qualitative at best.

Daily counts are highly misleading, as counts from different localities are not properly comparable unless the influencing meteorological parameters are the same. However, averages of the daily counts over a pollination season are useful for comparison with other localities, as the influencing factors usually tend to average out.

The daily counts, as taken with the Durham Sampler and reported by the news media, should be interpreted with an understanding of limitations of the sampler.

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Responses

  • sarah
    What is a durhams sampler?
    2 years ago

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