DRESSLERVILLE, Nev. — Smoke began billowing into the skies of northwestern Nevada in September, clouding the mountains, dimming the sun — and quashing residents’ hopes that they would be spared from wildfires and the awful air quality the blazes produce. The lung-irritating particles were blowing in from burning forests in California and settling in Douglas County, Nevada, home to nearly 50,000 people, prompting warnings that air quality had reached hazardous levels. Those levels meant the air was very unhealthy, bad enough to raise alarms about people’s immediate health care needs and questio…