Hi — I’d treat this as a material-filtering problem, not just a “which wood is best” question. If you already know certain woods are a problem, avoid any outdoor furniture that could expose you to those species, their dust, oils, resins, or wood flour. In an urban setting—parks, patios, plaza seating—that often means skipping solid cedar, redwood, teak, ipe, rosewood, mahogany, and other aromatic or oily hardwoods unless the maker can prove the exact species and that it’s fully sealed. I’d also avoid vague “hardwood” benches, unsealed or weathered wood that sheds splinters and dust, and damaged oil or varnish finishes that can transfer residue to skin or clothes. Pressure-treated lumber is another one to be cautious with if you’re chemically sensitive; it’s not a wood allergy per se, but the treatment can irritate. Wood-plastic composites are tricky: many contain wood flour, and once edges weather or boards are cut, those fibers can be exposed. Natural rattan and bamboo aren’t true woods, but they can collect dust and mold and irritate some people, so test before committing.
Better choices are powder-coated aluminum, stainless steel, galvanized metal with a good coating, HDPE recycled plastic, glass, stone or concrete, and metal mesh. For cushions, choose removable, washable covers and avoid damp, mildewed foam. If you really want wood, ask for species, finish, and certification; seal it and maintain it, or keep it fully covered. If your allergy is severe, metal or HDPE is the lower-risk route. A quick patch test or allergist check is smart before buying a whole set.