With no explanation, label text_A→text_B with either "DON'T KNOW", "NO" or "YES".
text_A: As a result of increasingly hot summers and its location within the Mediterranean region, which is often cited for having long episodes of pollution, Lebanon, Beirut in particular, is at high risk for air pollution. Approximately 93 percent of Beirut's population is exposed to high levels of air pollution, which can most often be attributed to vehicle-induced emissions, whether it be long-range travel or short commuting traffic. The cost of air pollution to health may exceed ten million dollars a year. The levels of air pollution in Beirut are increasing annually, and were already above acceptable WHO (World Health Organization) standards by 2011. The most noted pollution in Beirut is particulate matter (street dust), chemicals in the air, and vehicle exhaust. Air pollution is exacerbated by city structure as indicated by high buildings on narrow streets, which contain air pollutants, though strong urban management is now helping to mitigate pollution. Some recommendations for improvement of air quality include encouragement of carpooling and citywide biking, alternative fuels for vehicles, and a widened public transit sector.
text_B: Would someone constructing a building in Beirut have to worry about their building height in relation to street width?
DON'T KNOW.