HILO, Hawai'i — Emissions from the new vent at the summit of Kilauea volcano seem to have dropped off somewhat from the peak levels of last month, but the state still warned Pahala residents of poor air quality this week after average daily sulphur dioxide levels in that rural community climbed above federal limits on Sunday and Monday.

Scientists with the U.S. Geological Survey's Hawaiian Volcano Observatory reported that sulphur dioxide emissions from the vent that opened last month at Halema'uma'u dropped to about 700 metric tons Tuesday, which is a decline from its peak emissions of more than 2,000 tons.

However, the emissions were still far above the norm of about 200 metric tons per day at the summit, and the trade winds have been blowing most of the fumes toward Pahala.

Despite the sometimes thick vog and fumes, there has been only a modest increase in the number of people going to Ka'u Hospital because of respiratory problems, said Nona Wilson, director of nursing for the hospital.

The hospital has seen a few more cases than normal over the past few weeks where people with asthma or other respiratory problems come in because the volcanic emissions aggravated the problem, she said.

"The particulate matter doesn't seen to be as bad as it was a couple weeks ago," she said. "Of course, nobody knows what's going to happen from minute to minute and day to day."

The federal standard for sulphur dioxide, averaged over 24 hours, is 0.14 parts per million. The state Department of Health Pahala air monitoring station recorded a 24-hour average of 0.181 ppm Sunday and an average of 0.154 ppm on Monday.

Pu'u 'O'o on Kilauea's East Rift Zone has been producing about 2,000 metric tons of sulfur dioxide per day for years, while only about 200 tons per day was being released at Halema'uma'u at the summit. Sulphur dioxide emissions from the summit began to climb late last year, and by March 13 had climbed to record levels of 2,000 tons per day as a new vent opened in the wall of the crater.

The emissions at Pu'u 'O'o have held steady since then, which means the overall emissions from the volcano have roughly doubled.