A player's complaint that the smog made him vomit and the unflattering sight of fans in face masks have put Beijing's notorious air pollution back in the spotlight after haze hit this week's China Open.

"Hazardous" levels of smog cleared by Thursday, but not before Martin Klizan's angry tirade and pictures highlighting the murky air went worldwide on social and traditional media.

In a widely reported Facebook post, since deleted, the Slovakian world number 42 said he coughed uncontrollably and then vomited after his defeat to Fabio Fognini, and vowed never to play at the tournament again.

"Regardless of the result of today's match... it has been such an extreme smog in Beijing today that half an hour after the beginning of the match I started to cough uncontrollably after every point and I had to vomit after the match," the post read.

"There is such an extreme smog in this city, that due to my health, which should be a priority of every tournament organiser, unfortunately, I will have to leave this tournament out from my calendar for the rest of my tennis career."

Klizan later deleted the post, although several fans referenced the message in comments they left on his Facebook page.

New York Times journalist Christopher Clarey put further pressure on organisers when he tweeted: "Air quality should absolutely be a factor in whether a city gets to stage an outdoor tennis tournament...or not."

Tournament officials have not responded to a request for an interview and information about at what level of air pollution, if any, play would be suspended, and what contingency planning was in place.

Levels of PM2.5 particulates -- small enough to deeply penetrate the lungs -- were above 300 micrograms per cubic metre for much of Wednesday, according to the website of the US embassy in Beijing.

Measurements over 300 are rated as "hazardous" by the website and carry the warning: "Everyone should avoid all outdoor exertion." Chinese authorities this week issued a yellow alert for smog, the third highest.

- 'Cuts days from your life' -

Air pollution is a chronic problem for China and with a rising number of professional tennis events around the country, players' exposure is also likely to increase.

The Women's Tennis Association has eight events in China this year, while the men's Association of Tennis Professionals has three. Most of the matches are played outdoors.

The China Open was previously entangled in pollution controversy two years ago, when Swedish player Robert Lindstedt described Beijing as: "The city that cuts off days from your life every time you visit."

"I get dizzy when I get up. Yesterday I couldn?t recover between points in practice and was breathing heavily the whole hour... It?s just not healthy to be here," he added in his blog.

Three players have complained of dizzy spells this year although one of them, Eugenie Bouchard, suffered concussion in recent weeks, and Petra Kvitova blamed the glandular fever she has struggled with this year.

The third, Jo-Wilfried Tsonga, staggered on court in his first-round match on Monday, and had his heartbeat checked with a stethoscope before he lost limply to Austria's Andreas Haider-Maurer.

"I don't know. You know, nothing in me can calculate if it's enough oxygen for me or not. I just play tennis," said Tsonga, when asked if the pollution was to blame.

Many competitors have attempted to play down the situation or say that, after several years of visiting China, they are resigned to the smoggy conditions.

"Well, (it's) definitely tough. A little bit different than usual. But I think we're all kind of used to it, right?" said Polish fourth seed Agnieszka Radwanska.

Rafael Nadal inadvertently coughed before he dismissed the air pollution as "nothing new for us", while Angelique Kerber conceded: "It's a little bit difficult.

"It's the same for everyone. Of course, it's different than normal (conditions). But I'm trying to stay in my rhythm and just trying to not think about this, just trying to play," she said.