JOHOR BAHRU, Oct. 20 -- For delivery riders in Johor, escaping the thick haze that has settled over the state is not as simple as staying indoors. Their livelihoods depend on being out on the road, even as the polluted air takes a toll on their health.

As air quality reached very unhealthy levels in several parts of the state last week, riders reported sore throats, stinging eyes and other symptoms, leaving some to weigh the cost of fewer deliveries against the risks of prolonged exposure.

The haze, carried across the region by smoke from fires in Indonesia, has prompted Johor to extend school and educational institution closures until October 23, even as outdoor workers continue their daily routines.

For Ghani Jaafar, a 50-year-old fo...