There are over 10,000 brick kilns in Bangladesh, many of them illegal. Primitive in design, using low-grade coal, paper, even plastic for fuel, they have been identified as the single largest source of airborne pollution in the country. Poor rural families migrate to nearby cities to work in these fields- men, women, and children alike- from dawn to dusk, breathing air choked with smoke and dust, making less than the equivalent of $2 a day.