Air pollution concentrations will remain high over the next few days, possibly reaching unhealthy levels toward the end of the week according to the New Hampshire Department of Environmental Services. The polluted air consists of ozone pollution as well as small particles which have been blown up from urban areas by southwesterly winds.
The NHDES at first declared an air quality action day for most of southern New Hampshire on Saturday. Ultimately, however, pollution concentrations did not reach unsafe levels, the NHDES concluded.
"If we expect to have a 24-hour period that averages 40 micrograms, we'll issue a warning," Kathy Brockett, education and outreach coordinator of the department, said. "We'll tend to err on the side of caution."
Brockett expects air quality to remain poor throughout the week but to return to more healthy levels this weekend.
Many counties reached an orange level of pollution on Saturday, which signifies an unhealthy toxicity for persons with previous respiratory problems. Grafton County remained at safer green and yellow levels throughout the weekend.
The health risks associated with the elevated ozone and small-particle levels are all short term. They include coughing, wheezing, tightness of the chest and difficulty breathing, and tend to affect people with preexisting respiratory conditions more severely than others.
"Basically this week is going to be a long period of low air quality," said Dennis Tinsky, supervisor of the risk assessment section of the New Hampshire Bureau of Environmental and Occupational Health. "Once levels go down, those symptoms will go down."
According to Tinsky, there are no long-term effects of exposure to these particles are known, since levels typically return to normal levels within a few days.
"[The effects] tend to be very transient, one-day problems. The symptoms I described are by and large reversible," Tinsky said.
Over the last 20 years, the state has averaged nine days a year of unhealthy ozone levels. New Hampshire has not yet reached these unhealthy levels in 2005, though the NHBEOH has only started monitoring the concentrations of small particles in the last five years.
The unhealthy air is associated with recent southwesterly winds, which tend to carry small particles from urban areas into the state. Summertime sunshine causes the unsafe ozone levels.
Since ozone is formed by sunlight, its levels are highest in the late afternoon. To protect themselves, the NHDES recommends that people exercise in the morning if possible and avoid physical exertion if they have a preexisting respiratory condition.
"We tell people to take precautions and not take part in strenuous exercise," Tinsky said. "After levels go down, they can resume their normal activities."
