Short answer is that you will destroy lung tissue. Not sure if you mean HCl in aqueous solution or HCl gas. In the latter case, whether or not it is fatal will depend on how much you inhale, but you wonât need much. It will also harm the nose and throat. If it is dilute solution it will be a bit like choking on regurgitated stomach acid and could cause long term health problems.
Peelaway 7 Paint Remover is a suitable for use on all woods with more modern paint or varnish on. Both of these products are a paste like product that you leave on for 24/48 hours (depending on what the test area shows) and then peel off.
Scrub the concrete. Use a wire scrub brush or a scraper to remove the loosened paint. You could also use a pressure washer for outdoor concrete surfaces such as driveways or patios.. Scrape the mixture off. The paint thinner should have done most of the work for you, allowing you to remove most of the paint by simply scraping the mixture off with a hard plastic scraper. Add a second layer of mixture if there is remaining paint, and repeat the process.