How many {time-weighted average exposure limit} are for {arsenic} ?
What is the time-weighted average exposure limit for arsenic?
SELECT (COUNT(?obj) AS ?value ) { wd:Q871 wdt:P2404 ?obj }
SELECT (COUNT(?obj) AS ?objs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q871> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P2404> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj .
} 

What is the exposure limit of arsenic's time-weighted average exposure?