How the Air Quality Index can keep you safe from wildfire smoke entering New Jersey

Wildfires in Canada are sending heavy smoke across the northern U.S., and New Jersey is experiencing some of the worst air pollution it's ever seen.

As of 5 a.m., alerts had been issued for almost the entire state, with most of New Jersey in the unhealthy range.

The air quality has some Northeasterns wondering, for the first time, what is the AQI, or Air Quality Index?

What is AQI?

AQI, or Air Quality Index, is the measure of how healthy or unhealthy the air is.

How is the AQI calculated?

The Environmental Protection Agency and each state measure pollution and gasses like ozone to come up with a number that indicates how unhealthy the air is. The higher the number, the worse the air quality.

What is a healthy AQI level?

The AQI numbers run from 0 to 500. Here’s the breakdown:

• 0-50: Good. The air quality poses no risk.

• 51-100: Moderate. The air quality is OK for most people, but a few who are especially sensitive to pollution should be concerned.

• 101-150: Unhealthy for Sensitive Groups. Still OK for most people, but people in sensitive groups may experience respiratory effects.

• 151-200: Unhealthy. The air quality can affect everyone, and people with sensitivity may experience more serious respiratory effects.

• 201-300: Very Unhealthy. Everyone may experience serious health effects.

• 301-500: Hazardous. The entire population is likely to be affected.

What are the air quality alert colors?

• Good: Green.

• Moderate: Yellow.

• Unhealthy for Sensitive Groups: Orange.

• Unhealthy: Red.

• Very Unhealthy: Purple.

• Hazardous: Maroon.

What does the AQI chart mean?

As the AQI chart numbers gets higher, there are more warnings about ventilation and more restrictions on outdoor activities.

• Good: It’s fine to do normal activities and keep the windows open.

• Moderate: Some people would reduce outdoor exercise, and everyone should close windows.

• Unhealthy for Sensitive Groups: Everyone should reduce outdoor exercise, and people with health risks should consider wearing masks outdoors. Turn on air purifiers inside and do not open windows.

• Unhealthy: Everyone should wear a mask outdoors. Do not ventilate indoors.

• Very unhealthy: Remain indoors as much as possible. Do not exercise outside. Wear masks outdoors.

• Hazardous: Do not exercise and remain indoors with air purifiers on and windows shut.

This article originally appeared on NorthJersey.com: What is AQI in weather terms? How it protects you from wildfire smoke