Air quality in Seattle ranked worst among major cities worldwide Tuesday, according to AirVisual, a data visualization tool that tracks air quality.

AirVisual data showed Seattle’s air quality (Air Quality Index 181) was poorer than Portland, Ore. (AQI 175), Santiago, Chile (AQI 160), and Chengdu, China (AQI 153) on Tuesday.

However, Seattle’s air quality is slightly clearer compared to other towns and cities in Western Washington, which housed four of the top five stations with the worst air quality in the United States on Tuesday morning.

Bellingham, Cheeka Peak in Clallam County, Anacortes, and the Olympia-Tumwater-Lacey metro area all had “unhealthy” air, according to AirNow, a government agency that measures air quality. Those four cities had air quality indexes ranging between AQI 185 and AQI 190.

RELATED: Check air quality index in Washington

Pendleton, Ore. had the worst air quality in the country Tuesday, coming in at 201 AQI, which is considered very unhealthy.

WATCH: Doctor says don't vacuum with wildfire smoke in air

A second round of wildfire smoke has blanketed Western Washington since Sunday after shifting winds brought haze from fires in British Columbia and Eastern Washington. Air quality is expected to deteriorate further Tuesday before onshore winds bring improvement Thursday.

The smoke was so widespread that ash fell across Puget Sound on Monday. If ash falls on your car, don’t wipe it, because it could scratch the paint. Instead, thoroughly wash the car with soap and water.

WATCH: Expert explains dangers of wood smoke particles