London’s pollution index hit a 7 on a scale of 1 to 10 Thursday, on its third day of consecutive heavy smog reaching the Docklands and City financial districts.

According to the Department for Environment, Food and Rural Affairs, the pollution has been caused by a number of sources: local emissions, pollutants from the rest of Europe, and even fine sandy dust blown over from the Sahara Desert by air currents. Last month, heavy sandstorms raged throughout the desert that sent sand far into the atmosphere.

Though London’s current haze problem isn’t nearly as bad as the thick, soup-like smog that hung over the city in Victorian times, the European Commission threatened to sue the country due to its lack of monitoring nitrogen dioxide levels in accordance to European standards. A level of 7 is considered quite high; people with heart or lung problems were advised to not exercise until the pollution drops.

However, London doesn’t expect to see a significant reduction in nitrogen dioxide levels for another 11 years. City officials, meanwhile, say they will do their best to mitigate the issue. “I’m suffering too,” Energy Secretary Ed Davey told Parliament Thursday, according to Business Week. “Air pollution is a very serious issue. Most of the analysis shows that the air pollution that is most damaging in the U.K. comes from the transport sector. Clearly we will do everything we can and it makes yet another good reason for going green.”

There will be both short-term and long-term health consequences of this pollution spell. The immediate effects will manifest as breathing problems for people with asthma; outdoor air pollution can also irritate eyes. There was a 14 percent increase in ER calls among people with breathing problems, according to the London Ambulance Service. Long-term consequences, however, can range from worsened respiratory problems to an increased likelihood of cancer or heart disease.

The World Health Organization (WHO) states the air pollution is the cause of one in eight deaths every year, killing about seven million people worldwide annually. Most of the health problems stem from indoor pollution — like fumes from stoves — but outdoor pollution is nearly just as bad.

Cities in China, and now France, have experienced excessively high levels of air pollution most recently. In March, Paris announced a new traffic system that would ban half of the normal cars from driving in the streets in order to curb the unusually high pollution that was nearly up to par with Beijing. Asian cities in particular have high pollution from industrial causes. “Our worst days here are normal in Beijing,” Ellie Highwood, professor of climate physics at Reading University, told the Financial Times.