Visitors to Hawaii’s Big Island who suffer chronic respiratory problems are being urged to take common-sense precautions because of air pollution caused by volcanic activity.

Conditions are right for increasing particulate levels over southern and eastern parts of the Big Island, said Darryl Oliveira, chief of Hawaii County Civil Defense.

The lava eruption that began in June has not moved farther downslope toward the village of Pahoa, but its flow has widened. The molten rock burns dry vegetation in its path. That smoke, combined with ash from the Kilauea volcano, creates a haze that the locals call “vog.”