Texas air quality may be improving. The Environmental Protection Agency announced recently that it agrees with the Texas Commission on Environmental Quality that the Houston area is meeting federal guidelines for a particulate matter known as PM2.5. In heavy concentrations, PM2.5, composed of tiny particles less than 2.5 micrometers in diameter, can be hazardous.
There are three PM2.5 monitors in Houston, but only the Clinton Drive monitor, located in an industrial area near the Ship Channel, showed elevated readings. Electron microscopy showed that a large portion of the Clinton monitor samples consisted of soil and dust particles.
To reduce PM2.5 levels, the TCEQ enlisted the aid of the EPA, the city of Houston, Harris County, Port of Houston Authority, Port Terminal Rail Authority and local industry. Action taken included paving a nearby parking lot; installing barriers to prevent trucks from driving on dusty shoulders; putting new, cleaner railroad engines into service.
The PM2.5 levels at the monitor came down from the highest annual average reading of 16.0 micrograms per cu meter to the latest average of 12.6 micrograms per cu meter. Overall PM2.5 averages in Houston also declined from 13.2 micrograms per cu meter to 11.9 micrograms per cu meter. The federal standard for PM2.5 is 15.0 micrograms per cu meter.
Another factor was EPA recognizing some high monitor readings as caused by events that Texas does not control, such as smoke from agricultural burning in Central America.
