Life goes on under cloud of smog in Mexico CityScientists say breathing the heavily polluted air in Mexico City these days is like smoking somewhere between a quarter- and a half-pack of cigarettes a day. The trim 51-year-old was taking a break from his interval workout in the capital's largest park, the Bosque de Chapultepec -- which the authorities actually closed at one point this week, to hammer home the message that running or cycling in the middle of an air pollution alert was not a good idea. Authorities blame the problem on dozens of wildfires that have broken out across central Mexico in recent weeks, and the lack of wind or rain to disperse the resulting particles.