Black carbon fouls New York subway stations
Pollutant can cause breathing problems
![air pollution graph](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2014/12/graph_airpollution_0.png?fit=860%2C460&ssl=1)
BAD AIR Tiny black carbon particles drift through the air at several New York City subway stations. Underground stations collect the highest concentrations.
M.J. Ruzmyn Vilcassim et al/Environmental Science & Technology 2014