Clearly they don't want a source, it's just malicious ignorance. After all, if they really wanted to know it'd be far easier to click the "plus" button on their browser and ask DuckDuckGo.
Funny that you should mention that, because the first hit I get when I type "EVs PM2.5 pollution" into my search engine is a Science Direct article that contains the following quote: "Findings demonstrate that EV adoption can significantly alleviate PM2.5 pollution." Not that I am one to blindly believe whatever happens to show up at the top of my search results, but it shows the ridiculousness of your argument about how easy it is to just do a web search.
So I'd recommend for next time, keep your clairvoyance to yourself (because I "clearly" did want a source) and while your add it, perhaps also your offences ("malicious ignorance").
