Public Health and Safety Advisory Information
Last updated: August 7, 2025 at 11:58 AM
IMPORTANT: Measles outbreak in the United States. As of August 5, 2025, a total of 1,356 confirmed measles cases were reported by 41 jurisdictions: Alaska, Arkansas, Arizona, California, Colorado, Florida, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York City, New York State, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, Wisconsin, and Wyoming. Learn more.
This page provides important public health and safety information for Waltham, including community health alerts such as infectious disease outbreaks, air quality index, heat index, and winter weather alerts.
Advisory Information
Community Health Alerts
The following list includes infectious disease outbreaks, foodborne illnesses, and other public health concerns.
Air Quality Index
Air quality is measured using the Air Quality Index (AQI). Current air quality conditions can be found on AirNow.gov.
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The AQI is a scale used to measure air quality and the level of pollution in the air.
Poor air quality can cause or worsen respiratory and cardiovascular conditions. People with asthma, allergies, or other health conditions, as well as young children and the elderly, are especially vulnerable.
- Good to Moderate (AQI 0-100): Air quality is generally acceptable, but individuals who are sensitive to air pollution may experience minor health effects.
- Unhealthy for Sensitive Groups (AQI 101-150): Sensitive individuals (e.g., those with pre-existing respiratory conditions) should limit prolonged outdoor exertion.
- Unhealthy (AQI 151-200): Everyone may begin to experience health effects, and sensitive groups will experience more serious effects. Limit outdoor activities, especially strenuous ones.
- Very Unhealthy (AQI 201-300): Health alert. Everyone should avoid outdoor activities.
- Hazardous (AQI 301+): Health warnings of emergency conditions. The entire population is likely to be affected.
For more detailed information on how to protect yourself during various air quality levels, visit the AirNow website.
Heat Index and Safety Guidelines
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Heat Index is a measure of how hot it feels when relative humidity is factored in with the actual air temperature. Higher humidity can make the air feel hotter, even if the temperature is not extreme.
Extreme heat can lead to serious health issues such as heat exhaustion or heat stroke, particularly when combined with physical exertion. The risk of heat-related illness increases for people who are not accustomed to the heat, those with certain medical conditions, and the elderly.
- Heat Index Below 90°F: Generally, there is no immediate risk to health. However, prolonged exposure to direct sunlight or physical activity may increase risk.
- Heat Index 90°F-104°F: Be cautious, especially with prolonged outdoor activities. Drink water frequently and take breaks in the shade or indoors. Avoid strenuous activities during the hottest parts of the day.
- Heat Index 105°F-129°F: Heat exhaustion is possible. If you must be outdoors, wear light clothing, stay hydrated, and take frequent breaks in cool, shaded environments.
- Heat Index 130°F or higher: This is considered dangerous. Limit outdoor activities and stay indoors with air conditioning when possible. Seek medical attention if you experience symptoms of heat stroke or heat exhaustion (e.g., nausea, dizziness, rapid heartbeat).
Winter Weather Alerts
The following information will direct you to resources about local cold weather advisories and winter weather safety information.