London is exceptionally smoggy right now, and at least some of the air pollution can be blamed on dust that traveled all the way from the Sahara. "We usually see this happen several times a year when big dust storms in the Sahara coincide with southerly winds to bring that dust here," one expert tells the Guardian. Another explains, "The main sources [of air pollution] we have are vehicle transport and the industrial process; when you put that alongside the unusual weather consequences like the Saharan dust ... then that's when you get these few days of unusually high pollution."
How high? Air pollution is expected to reach an eight or nine on the UK's 10-point scale in many parts of southern England and Wales today, and could even hit 10 in some areas along the coast, leading experts to advise "vulnerable people," such as those who suffer from asthma or heart problems, to stay inside as much as possible. As the AP describes it, many cars are "covered in a film of red dust." Conditions are expected to worsen through tomorrow as the smog travels through more of the UK, but should ease a bit by Friday. "More dust rain is possible during showers expected later this week," one expert warns.