Is It Safe to Go Outside? How to Navigate This Cruel Summer.

Excessive rain and flooding in the Northeast, a dangerous heat wave with triple-digit temperatures across the South, West and Midwest, and smoke from wildfires in Canada have come together to make this a summer of weather extremes in the United States, in which going outside can be riddled with perils.

So how do you know when it’s safe to venture out?

“No matter what the extreme weather situation is, there are usually a few practical steps you can take” to reduce your risk, said Alex Lamers, an extreme weather expert at the National Oceanic and Atmospheric Administration. Here are the things to consider before you head out the door.

<b>Extreme Heat</b>

Extreme heat leads to hundreds of fatalities a year in the United States. That is in large part because high temperatures are taxing on the body, even for short periods of time, said Dr. John Balbus, acting director of the office of climate change and health equity at the Department of Health and Human Services. Before you go out on a very hot day, make a plan for how you’re going to protect yourself.

<b>What to Check For:</b> Temperature alone isn’t enough information to gauge health risk; the body struggles more to cool itself in humid conditions. The heat index, which combines temperature and humidity, is a more accurate measure of what heat feels like. The higher the heat index temperature, the more dangerous it is to go outside. A heat index of 103 degrees Fahrenheit and above is dangerous; you’re likely to experience heat cramps and heat exhaustion, and heatstroke is possible if you’re outside for a prolonged period or doing something strenuous, according to the National Weather Service.

<b>Where to Check:</b> Put your local air temperature and humidity level into the heat index calculator from the weather service to get a localized heat index, or download an app, such as the OSHA-NIOSH Heat Safety Tool from the Centers for Disease Control and Prevention, which will calculate it for you. The New York Times heat tracker also features the daily heat index and a six-day forecast using NOAA data.

<b>What to Do:</b> If the heat index is 103 degrees or above, avoid vigorous activity outdoors and limit your exposure to the heat, Balbus said. If you are pregnant, older than 65 or have an underlying health condition, you may need to be cautious even at lower heat index levels.

<b>Excessive Rainfall</b>

If it’s raining hard, or has been raining for many hours, you’ll want to stay informed about the risk of flooding in your area. The best way to navigate a flood situation is to prepare early, Lamers said, and being aware of your risk levels will help you prepare.

<strong>What to Check For: </strong>The weather service sends out categories of flood alerts. A flood watch means that “the ingredients are in place but the flooding hasn’t necessarily developed yet,” Lamers said. A flood warning “is when flooding is imminent or it’s actually occurring.” A flash flood warning refers to rapid rises of water coming within a few hours or less.

<strong>Where to Check: </strong>The weather service and state and local authorities will send relevant alerts to your phone (enable these kinds of alerts in your phone’s settings) and will broadcast them on the radio. Alerts are also available on weather.gov. NOAA produces excessive rainfall outlooks on its website that highlight the potential for flash flooding over the next five days.

<strong>What to Do: </strong>If there’s a flood watch alert in your area, be prepared to change your plans or even evacuate, Lamers said, especially if you live in a flood-prone area — one close to a body of water or in a low-lying region — or if you live in a basement-level apartment.

A flood warning usually comes with localized instructions, but as a general rule, if you are in a flood-prone area, the Federal Emergency Management Agency recommends moving to higher ground or a higher floor as soon as you can. Otherwise, stay put and keep an eye on weather alerts on your phone or the radio.

<b>Poor Air Quality</b>

Monitoring the Air Quality Index, particularly as the wildfires in Canada continue to send plumes of smoke across the United States, can help you minimize related health risks.

<strong><strong>What to Check For:</strong> </strong>The AQI measures levels of ground-level ozone, particle pollution, carbon monoxide, sulfur dioxide and nitrogen dioxide in the air to determine a score from 0 to 500; the higher the number, the greater the level of air pollution. An AQI between 101 and 150 is considered moderate but might present risks for vulnerable groups, including children, adults older than 65 and those with underlying health conditions, such as asthma, Balbus said. An AQI above 150 is considered unhealthy for everyone.

High heat can worsen air quality by raising ozone levels, Balbus said.

<strong><strong>Where to Check:</strong> </strong>The AQI can be found at AirNow.gov or on the AirNow app, both of which are run by the Environmental Protection Agency and rely on data from observation sites across the country, Lamers said. The Times air quality tracker also features the daily AQI across the United States using data from AirNow.

<strong>What to Do: </strong>If the air quality is poor, plan to stay indoors as much as possible with the windows closed. If you must be outdoors, consider wearing an N95 mask to help reduce your exposure to toxins, Balbus said.

This article originally appeared in <a href="https://www.nytimes.com/2023/07/20/well/live/air-quality-heat-flooding-safety-check.html">The New York Times</a>.