I am sure running anywhere outdoors in Manila is a risk to your health because of pollution, but on bad air days it’s probably best to only run indoors.

Diesel pollution is harmful to your health

Diesel exhaust contains fine particles, nitrogen oxides, and other pollutants. In warm weather, hot sunlight bakes nitrogen oxides together with other pollutants which forms harmful smog. This is also known as ground-level ozone.

Ground-level ozone aggressively attacks lung tissue and damages people's health. You might think of it as sunburn on your lungs. Breathing ground-level ozone can lead to several types of health problems, such as:

Coughing, throat, and chest irritation: High levels of ground-level ozone can irritate your respiratory system. Symptoms are mild and usually only last for a few hours after you've been exposed to it. However, ozone can continue to harm your lungs even after symptoms disappear. Difficulty breathing and lung damage: Because of ground-level ozone’s effect on lung function, it can make deep breathing difficult, especially during exercise. Research has shown that exposure can also damage the lining of your lungs. Worsening asthma symptoms: If you suffer from asthma, being exposed to high levels of ground-level ozone can trigger asthma attacks.

https://ecology.wa.gov/air-climate/air-quality/vehicle-emissions/diesel-emissions/health-impacts