SAN ANTONIO -

Tuesday’s Mountain Cedar count of 31,000 grains per cubic meter was only the third time in the last 13 years that the reading surpassed 30,000, according to allergist Dr. Paul Ratner. 

That number is one many in San Antonio rely on, but just how is it determined?

For 30 years, Ratner and his co-workers at Sylvania Research have been calculating a pollen count.

"This is the device that we use to collect the pollen,” said Ratner. “It’s a fairly simple box called a Sample Air."

The small, unassuming black box is responsible for predicting many allergy sufferers' misery.

"What we'll do is take a glass slide, put some grease on it, which will help trap the pollen,” said Ratner.

"I'll take it off and put it under the microscope,” said Shannon Syring, Ratner’s co-worker. 

Syring collects the sample each morning, inspects the grains of pollen under a microscope, and calculates a number.

"When you see it under the microscope, you almost can't believe it, because it's just covered,” said Syring.

According to Ratner, this cedar season is one of the worst in 14 years. The pollen count, which continues to be high, serves as a “snapshot” of how much pollen is in the air each day. The count is taken in north San Antonio, and pollen concentrations can vary across the city.  The number that is presented each day represents the peak grains per cubic meter observed in a 24-hour period.

So what does 31,000 grains per cubic meter actually mean to those who suffer from allergies?

"A cubic meter of air would be a box basically 3 feet by 3 feet by 3 feet,” said Ratner.

Imagine 31,000 microscopic grains inside that box.

"There's 250 pollen grains in 1 inch and (if you) spread those out, it would be a line about 10 feet long of pollen,” said Ratner.

It is an idea that makes most people sneeze just thinking about it. 

According to Ratner, any reading around 10,000 to 15,000 grains per cubic meter can bother just about anyone.

For a list of recent stories Justin Horne has done, click here.