The eruption has hit the island's tourism industry.
Big Island summer hotel bookings have dropped by almost half from last year, Rob Birch, executive director of the Island of Hawaii Visitor Bureau, told journalists on a conference call.
College exchange student Constantin Plinke, 24, was planning to go to the Hawaii Volcanoes National Park before it was shut.
"We had a big list of things to do and maybe 80 percent of them were in the national park," he said, after stopping by the side of the road to watch ash plumes rising into the air. "It's sad."
The area taking the brunt of the eruption is about 25 miles (40 km) down Kilauea's eastern flank, near the village of Pahoa. Lava has burst from the ground to tear through housing developments and farmland, threatening one of the last exit routes from coastal areas, state Highway 132.
The latest fissure in the earth opened on Tuesday, spewing lava and toxic gases that pushed air quality into "condition red" around Lanipuna Gardens and nearby farms, causing "choking and inability to breathe," the Hawaiian Volcano Observatory and Hawaii County Civil Defense said.
Road crews put metal plates over steaming cracks on nearby Highway 130 and reopened it to give coastal residents an escape route should a lava flow reach the ocean and block another road, Highway 137, Civil Defense said.
No major injuries or deaths have been reported from the eruption.
A looming menace remains the possibility of an "explosive eruption" of Kilauea, an event last seen in 1924. Pent-up steam could drive a 20,000-foot (6,100-meter) ash plume out of the crater and scatter debris over 12 miles (19 km), the USGS said.