Smoke from the 1,300-acre Soledad Fire near Santa Clarita has caused unhealthy air quality for the Santa Clarita Valley and the San Gabriel Mountains, officials said Monday.

The blaze, which started about 3:30 p.m. Sunday near Soledad Canyon Road and the 14 Freeway and spread along the highway, is now 30% contained.

The South Coast Air Quality Management District asks residents to avoid unnecessary outdoor exposure and limit outside physical activities. In addition, people and children who have conditions that make them sensitive to air quality should stay indoors as much as possible, even in areas where smoke, soot or ash can’t be seen, or there is no smell of smoke.

“It is difficult to tell where smoke, ash or soot from a fire will go, or how winds will affect the level of these particles in the air, so we ask everyone to remember that smoke and ash can be harmful to health, even for people who are healthy,” L.A. County health officer Dr. Muntu Davis said in a statement Monday. “If you can see smoke, soot, or ash, or you can smell smoke, pay attention to your immediate environment and take precautions to safeguard your health.”

Smoke from wildfires contains a mixture of small particles, gases and water vapor, and those small particles are the primary health concern, officials explained. They can cause burning eyes, runny nose, scratchy throat, headaches and even illnesses like bronchitis. Those with sensitive conditions can experience difficulty breathing, wheezing, coughing, fatigue and chest pain.

“When smoke is heavy for a prolonged period of time, fine particles can build up indoors even though you may not be able to see them,” officials said. “Wearing a mask may prevent exposures to large particles. However, most masks do not prevent exposure to fine particles and toxic gases, which may be more dangerous to your health.”

Day camps in the areas affected by the fire were asked to suspend outdoor recreational activities, officials said.

Indoor actives are OK in areas where smoke is visible, as long as the location has air conditioning that doesn’t draw air from outside and windows are closed.

Officials also advised residents to avoid air conditioning units that only draw in air from the outside, or do not have a re-circulating option.

If it’s too hot to stay indoors and air conditioning is not available, officials recommend that residents visit an air-conditioned public place.

Officials recommend that residents not use fireplaces, candles and vacuums when air quality is bad, and to use damp cloths to clean dusty outdoor surfaces.

Smoking is also not recommended.

Officials ask that anyone experiencing severe coughing, shortness of breath or difficulty breathing, wheezing, chest tightness or pain, palpitations, nausea, unusual fatigue or lightheadedness call a doctor or visit an urgent care center. Call 911 if an issue is life-threatening, officials advise.

Pets could also be affected by poor air quality and should not be left outdoors, officials said.

If dogs or cats appear to be in respiratory distress, officials advise residents to take them to a hospital immediately. Symptoms in dogs include panting or inability to catch their breath. Symptoms for cats are less noticeable but also include panting or an inability to catch their breath.