It took 15 minutes for officials to treat riders and clear the area before the race resumed.
Protesting French farmers brought the Tour de France to a temporary standstill earlier today, with bales of hay reportedly being thrown onto the cycling route - prompting a swift reaction from local police.
Those riders included Geraint Thomas (wearing the overall leader's yellow jersey) and world champion Pete Sagan, who were seen washing their faces with bottles of water.
The former Tour of Flanders and Liege-Bastogne-Liege victor was helped back up on to the road and given first aid before resuming the stage in the company of a group of frontrunners.
After the Formula 1-style grid start in Bagneres-de-Luchon, which saw overall leader Thomas line up directly ahead of Froome and Dumoulin, it was Estonian rider Tanel Kangert who led the breakaway.
"I felt a tingle in the eyes, and in the back of my throat".
"My throat, nose and eyes were burning afterwards, but I think quite a lot of riders were in a similar situation", the four-time Tour victor said. "But I think quite a lot of riders were in a similar situation". He had been 57.2 kilometres from the finish and in the lead of the 218km-long stage at the time of the crash. Police also said they stopped the race to avoid other riders being affected by the gas.
He told his following that: "As always I will come back stronger!"More news: Sky rider Moscon expelled from Tour de France for hitting rival
"A cyclist's job is unsafe as it is", said Prudhomme.
"The road should remain free, we are not going to lock the riders in a stadium or on a tennis court", he said.
The gas was used to disperse the protesters, but it ended up blowing in the direction of the peloton, which led to the race being stopped at the 187km-to-go point.
"I want to say that I'm happy to be here after that tough moment", he said.
The small group of farmers from the Aude department were protesting a planned reduction of European Union funding, according to French authorities. Marco Bertorello / AFP/Getty Images Protesters attempted to use a flock of sheep and bales of hay to block to Tour de France route on Tuesday.
This Tour has been marred by incidents as race organizers struggle to deal with angry fans protesting against Froome's participation. He was cleared only just before the Tour.
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