Gasoline and diesel vehicles and factories are conspicuous sources of air pollution in Southeast Asia and elsewhere, but they're not the only ones. In South Sumatra, air pollution worsens during the dry season due to forest fires resulting from slash-and-burn and peatland drainings by companies and farmers looking to clear their land. In response, a group of South Sumatra residents filed a civil lawsuit against three pulpwood plantation companies last August for the chronic smoke haze produced by recurring fires on their concessions.