When Faisal Khan left the St. Louis County council meeting Tuesday after promoting a new mask mandate, he said he was shoulder-bumped and pushed by people in the aisle.

When he made it through the door, the St. Louis County Department of Health’s acting director said things got worse. Khan was surrounded by an “angry mob,” he said, and called an expletive and a brown b-----d. Others mocked his accent.

“It was the saddest, most bizarre and disgusting thing that I've ever witnessed in my 30 years in public health,” he told The Washington Post on Wednesday night. “I would hope that even the community members who were in attendance to speak out about and oppose the mask mandate would be shocked at the behavior of some people in the crowd.”

Khan on Wednesday wrote a letter to Rita Days (D), the council chairwoman, describing the shock and disappointment he felt over the treatment he faced.

“After being physically assaulted, called racist slurs, and surrounded by an angry mob, I expressed my displeasure by using my middle finger toward an individual who had physically threatened me and called me racist slurs,” he wrote.

St. Louis Mayor Tishaura Jones (D) and County Executive Sam Page had announced on Monday a new face mask requirement for indoor public places and transportation. Covid-19 rates in the region have crept up to levels not seen since February, and Khan said during Tuesday’s council meeting that infections from the new delta variant have reached an all-time high.

His comments were met with heckles from some in the crowd. The racial slurs and physical abuse he said he faced when leaving reflect the “deterioration of the political discourse in the United States.”

“The deliberate politicization of a public health emergency, beginning in early 2020 onward, really resulted, I feel, in this sort of situation,” Khan told The Post. “What I witnessed [Tuesday] night was just one symptom of this.”

Khan is the latest public health official to describe threats or mistreatment during the global pandemic. A 56-year-old Maryland man was charged this week with threatening to harm Anthony S. Fauci, the nation’s top infectious-diseases expert. Public health officials in Germany, Australia and Sweden have also been threatened for suggesting precautions to prevent the spread of a deadly virus that has killed more than 4 million globally.

Since the start of the pandemic, more than 250 public health officials have left the field, CNN reported in May.

Khan said when he walked into the crowded St. Louis County council meeting to find so many people packed into the chamber without face masks, he immediately feared it would become a superspreader event.

While Khan said he welcomed the chance to explain the importance of the mask mandate to members of his community, some council members argued only they — not other county officials — had the authority to enact one. Missouri Attorney General Eric Schmitt (R) also filed a lawsuit on Monday to stop the newly imposed mandate.

Khan told The Post he fears confusion over masks will only lead to misery. What’s important is not which county body approves the mask mandate, he said, but rather that it be enforced as the highly contagious delta variant spreads.

“The house is on fire,” Khan said of the county’s current health crisis. “We’re standing in front of it debating about which fire hydrant we should connect the fire hose to — whether we should enact mask mandates this way or that way. That is how absurd this situation is.”

Khan’s letter to Days describes his decades of public health work across the globe, including in Pakistan, South Africa, China, Australia and Zimbabwe.

“In all that time and in all those places, I have never been subjected to the racist, xenophobic, and threatening behavior that greeted me in the County Council meeting last night,” Khan’s letter states.

As of Wednesday night, Khan said his letter was met only with “deafening silence.” Days did not return a request for comment from The Post late Wednesday.

Khan said he is appealing to elected officials at every level to allow public health experts to protect their communities instead of painting them as tyrants who want to control people’s lives.

The delta variant is proof that the coronavirus is quickly morphing to find new targets, he added, warning that “time is not on our side.”

“Please do not tie our hands behind our backs,” he said in the interview with The Post. “Please do not seek to take over pandemic emergency response from us.

“We are not the enemy.”