Although amber haze has lifted from the College Area and the San Diego State campus has reopened, the air quality is still an issue on people’s minds.

Yesterday, the sky around campus looked similar to how it would on a normal October day, but the air quality was only moderate downtown and very unhealthy in El Cajon, according to the Air Pollution Control District Web site. These ratings are based on the amount of Particulate Matter in the air. PM that are smaller than 10 microns – less than one one-hundredth of the width of a paper clip – can cause respiratory problems. PM 2.5 are two and a half microns across and it is the amount of these particles in the air that the air quality ratings are concerned with.

“The reason that these size particles are a concern is that the nose can filter out things that are 10 microns or larger, so the nose and the sinuses do a good job with that filtration,” Ross Porter, communications director for the American Lung Association of San Diego and Imperial Counties, said. “When it’s smaller than 10 microns, it’s invading the body’s defenses and getting down into the airways and the airsacks.”

Today, air quality in the area is expected to be moderate.

The campus was opened today based on information from those agencies and inspections of on-campus facilities, Foster said. The Physical Plant has checked all of the air filters on campus and has replaced them if necessary.

“In some cases, students may smell residual smoke in certain buildings on campus, but that should not be a concern,” he said. “The air quality in the buildings has been determined safe.”

In addition, the Physical Plant staff has also cleaned up campus as much as possible, Foster said. Walkways have been swept to keep ashes and debris away from doors.