Texas has already seen 25 chemical emergencies this year. Here’s how to protect yourself during the next one.

Gather some useful supplies before a chemical emergency occurs. Yvette Arellano, founder of Fenceline Watch, an environmental watchdog organization, said “the way you prep for a chemical disaster and a natural disaster is so similar because you're trying to protect yourself against what is outside. You are trying to protect yourself from the chemicals in the air.”

The difference, said Shiv Srivastava, a policy researcher at Fenceline Watch, is that “it’s always chemical season.”

A basic disaster kit should include food, water and other supplies to last for several days, according to the U.S. Department of Homeland Security. Most supplies can be bought at home improvement stores.

A basic kit includes:

• Clear plastic sheeting and duct tape to seal windows and doors (Fenceline Watch recommends between four to six mils thick)
• Razor or box cutter to cut the plastic sheeting
• One gallon of water per person per day
• Non-perishable food
• Flashlight
• First aid kit
• Batteries
• Whistle to signal for help
• Dust mask to filter contaminated air (Fenceline Watch recommends N95 masks)
• Moist towelettes, garbage bags and plastic ties for personal hygiene
• Wrench or pliers to turn off utilities that could leak methane
• Manual can opener for food
• Local maps
• Cell phone with chargers and backup battery

Arellano recommends practicing sheltering in place — sealing windows, doors and air conditioning units with plastic sheets.

For people who don't have tarps or plastic sheeting, Arellano said rolling up wet towels and putting them at the bottom of exterior doors helps prevent airborne toxins from getting inside.

Consider packing additional emergency supplies such as prescription medications and important documents, such as insurance policies, in the event that you’re ordered to evacuate.

The EPA maintains a database of industrial facilities that must report how they manage toxic chemicals. To see where such facilities are located near you, use the EPA’s Toxics Release Inventory, and search by your metropolitan area or community profile.

Dallas and Houston residents can also use an interactive map developed by environmental groups that shows industrial facilities in those cities.

Texans can view the air quality forecast for their area and the latest levels of ozone and particulate matter for most regions of the state on the Texas Commission on Environmental Quality’s website.

During chemical incidents, the TCEQ creates an alert on the top left corner of its website’s homepage that directs people to information about the incident. Companies and local governments may also announce hotlines that citizens can call for information during chemical emergencies.

For Houston area residents, Harris County Pollution Control Services and Department maintains an air pollution data dashboard that provides real-time information about air quality. You can watch a video on how to navigate the dashboard on their YouTube channel.

During a chemical emergency, local governments often do additional air monitoring.

“We can integrate that data into our database, so that it’s very transparent and people can see,” Latrice Babin, Harris County Pollution Control’s executive director, told the Tribune earlier this year. “It’s not real time, but it’s as near real time as we could possibly get.”

The TCEQ maintains real-time air quality information gathered from the agency’s more than 200 stationary air monitors across the state.

To see more in-depth air quality data from a monitor near you, use TCEQ’s Geographical Texas Air Quality Monitoring Dashboard. Click the name of the monitor closest to your location, then select the name of the monitor from the list on the right side of the page to load the air monitoring data. The data can be difficult to understand and many monitors don’t measure airborne chemicals at all — about 80 of the air monitors measure toxic chemicals like benzene, near petrochemical sites.

The EPA sets national air quality standards for six pollutants: carbon monoxide, lead, nitrogen dioxide, ozone, particle pollution and sulfur dioxide. The standards are intended to protect the public, including sensitive populations such as children and the elderly, and can be viewed on the EPA’s National Ambient Air Quality Standards table.

During emergencies, look online for information from local emergency managers. You can often sign up for automated text or email alerts from both the city and the county emergency management departments.

For example, Harris County’s Ready Harris website sends out emergency alerts to residents during chemical fires and other industrial incidents.

The county’s pollution control department also encourages residents to follow the county’s social media including Twitter, Facebook, Instagram, and Next Door, because it allows officials to quickly share information with residents during an emergency.

Some industrial facilities may also report chemical incidents to a community message line. For residents in Harris County, you can check the Community Awareness Emergency Response website, where participating facilities post chemical incidents, including where they happened and whether any action is required by community members.

During a chemical incident, local officials may recommend that residents shelter in place.

To shelter in place during a chemical emergency, minimize airflow in the home by turning off furnaces, air conditioners, fans and heaters, according to the Federal Emergency Management Agency.

You can use plastic sheeting to seal windows. Use duct tape to help cover gaps around windows and doors.

Babin, of Harris County Pollution Control Services and Department, said some residents may decide to shelter in place when air quality readings show some risk even if local officials have not recommended doing so — such as people with respiratory conditions, older people and those with young children.

“Even if there’s not a shelter in place called, you can protect yourself,” she said.

Issuing a shelter-in-place advisory is an extraordinary measure, and at times, the pollutant may dissipate quickly before officials decide to warn the public, she said.

“Even if the jurisdiction has not called it, if you know there’s a level of benzene … in your area, you can say, ‘Let’s not go outside,’” she said.

Sheltering in place can be an emotional rollercoaster, said Arellano of Fenceline Watch. Once a shelter-in-place advisory is recommended, residents must work quickly to seal all windows and doors shut. Then, the waiting begins for emergency updates.

“It's just about calming down at that point,” Arellano said.

Arellano recommends buying board games and finding ways to distract yourself.

Some chemical emergencies may require you to evacuate the area, according to the Centers for Disease Control and Prevention.

During an evacuation, the CDC recommends that you follow instructions given by police, fire or other local emergency officials. You will know whether you need to evacuate by listening to the radio, television or reading local news online. You may get a text message alerting you to the evacuation recommendation or order. Remember to take your disaster kit!

Common signs of chemical exposure include — skin irritation; runny nose; coughing; shortness of breath; and eye, nose and throat irritation. Existing sinus or asthmatic conditions may become more aggravated. Monitor how you feel and consider contacting your doctor for advice, Harris County Public Health officials said.

Smoke inhalation from any fire can irritate people’s lungs, especially those who have asthma or other respiratory medical conditions, according to the EPA.

"It is often best to stay inside and close all windows and doors as a precaution," Eddie Miranda, a spokesperson for the Harris County Public Health Department wrote in an email. "Seek medical help if your symptoms are extreme or persist over an extended period of time."

If your clothes have become contaminated with chemicals, carefully remove all clothing and other items in contact with your body, the U.S. Department of Homeland Security recommends. Put all contaminated items in a plastic bag and seal it. Next, immediately wash hands and other exposed skin with soap and water, including after helping someone else decontaminate. Flush your eyes with water and gently wash your face and hair with soap and water before thoroughly rinsing with water.

If you were exposed to airborne chemicals, such as smoke or volatile organic compounds, the best thing to do, according to the Harris County Health Department, is to stay indoors as much as possible or find an area with fresh air. If possible, leave the area where there are chemical fumes. Lots of sleep also helps your body recover.

If you experience symptoms after being exposed to chemicals, seek medical attention as soon as possible.

The Harris County Health Department recommends that people with severe symptoms go to an emergency room. You do not need health insurance to get emergency room care, and many hospitals, especially nonprofit ones, offer charity care programs or payment plans to help patients with care costs.

"Be alert, take note of your symptoms, and whenever you're beginning to feel really unwell seek medical attention," said Inyang Uwak, a research and policy director for the environmental advocacy group Air Alliance Houston and environmental epidemiologist.

If you need medical advice for milder symptoms at a lower cost, you can try visiting a walk-in clinic or community health clinic. Community clinics serve uninsured patients; you can find one in your area here.

For uninsured patients in Harris County, the Harris Health System can provide financial assistance. See if you qualify and find more information at harrishealth.org. The Harris County Health System also provides a referral list of several clinics at the “Health and Wellness Clinics” page on its website, hcphtx.org.

Uwak recommends documenting when symptoms began and describing them to a doctor in detail.

"You were coughing the other day? How long was the cough? When did it happen? It's important to be specific,” Uwak said.

The Harris County Public Health Department recommends sharing all symptoms resulting from exposure with your healthcare provider, even minor ones or other symptoms that may have subsided or passed.

“Start first with the existing symptoms that you are most concerned about,” Miranda, the department’s spokesperson, wrote in an email. “Take notes of what you've been feeling, what day and at what time prior to your visit.”

He also said it is helpful to share any medical history or pre-existing health conditions.

Specific tests will depend on what the doctor recommends based on your symptoms and the chemicals you were exposed to, but might include blood, urine and X-rays or CT scans.

María Méndez contributed to this story.

Disclosure: Air Alliance Houston and Facebook have been financial supporters of The Texas Tribune, a nonprofit, nonpartisan news organization that is funded in part by donations from members, foundations and corporate sponsors. Financial supporters play no role in the Tribune's journalism. Find a complete list of them here.