sentence1: Cairo is now home to some 15 million people - a burgeoning population that produces approximately 10 , 000 tonnes of rubbish per day , putting an enormous strain on public services . In the past 10 years , the government has tried hard to encourage private investment in the refuse sector , but some estimate 4 , 000 tonnes of waste is left behind every day , festering in the heat as it waits for someone to clear it up . It is often the people in the poorest neighbourhoods that are worst affected . But in some areas they are fighting back . In