London Mayor Sadiq Khan has officially deemed the destination's air pollution a "health crisis" as levels have surpassed those in Beijing—a city infamous for its smog.

The Telegraph reported that readings from Monday afternoon reached a peak 197 micrograms per cubic meter for particulate matter on the Air Quality Index. The undesirable conditions have been attributed to traffic pollution and wood burning stoves.

Cold and calm weather conditions have also contributed.

Experts from King's College London told the Telegraph that London's air pollution has reached its worst level since April 2011. "This was the largest contribution from wood burning measured during the winter so far," a King's College spokesman told the Telegraph.

Unsurprisingly, the smog has had an impact on travel in and out of the popular European destination, with London's Heathrow Airport forced to cancel roughly 100 flights on Tuesday because of the reduced visibility.

More than 100 flights were also canceled at Heathrow on Monday, according to flight-tracking website FlightAware.com.

As of 9:30 p.m. local time (4:30 p.m. ET), Heathrow has canceled 24 flights and delayed nearly 290 other flights scheduled for Wednesday. Meanwhile, nearby London City Airport has canceled more than 50 flights for Wednesday.

The troublesome pollution is likely to provide additional encouragement for city officials as they look to create a cleaner and greener London for the future. According to Khan's outline, goals include purchasing clean electric and hydrogen buses, kicking off a major tree-planting program, rolling out clean walking routes and opposing the construction of a third runway at Heathrow, among others aimed at cleaning up the air.

Follow @_Pat_Clarke