Code Orange air quality alert: Why warm, sunny weather Friday will cause problems for some

May 11—The weather is expected to be quite pleasant in the Lehigh Valley on Friday, but those same conditions could create problems for those with breathing difficulties.

The Pennsylvania Department of Environmental Protection has issued a "Code Orange" Air Quality Action Day alert for Friday. In addition to Berks, Lehigh and Northampton counties affected areas include Philadelphia and the surrounding region (Bucks, Chester, Delaware and Montgomery counties) and the Susquehanna Valley (Cumberland, Dauphin, Lancaster, Lebanon and York counties).

"Mostly sunny skies, warm temperatures, and light winds from the west and southwest will likely contribute to 8-hour average concentrations of ozone in the Code Orange range on Friday," according to the alert.

People who are vulnerable to the effects of air pollution — the elderly, young children and those with breathing problems such as asthma, emphysema and bronchitis — are advised to stay inside as much as possible.

Everyone is asked to help reduce ozone air pollution by driving less or carpooling, getting gasoline after dusk, and conserving electricity.

What air quality alerts mean

Air quality is categorized by a color-coded system:

— Green: Good

— Yellow: Moderate

— Orange: Unhealthy for sensitive groups

— Red: Unhealthy for everyone

— Purple: Very unhealthy

— Maroon: Hazardous

Air Quality Action Day alerts are issued when the air quality index is forecast to be orange or higher.

The chart below provides more detail on the index values and the corresponding color codes.

Weekend forecast

The warm, sunny weather will continue through the weekend and into next week, with only a slight chance of showers Saturday morning. After that, there isn't a hint of the rain in the forecast through late next week.

Below is the extended National Weather Service forecast for Berks County and the Philadelphia region:

Thursday night: Mostly clear. Lows in the mid 50s. West winds 5 to 10 mph.

Friday: Mostly sunny. Highs in the mid 80s. West winds 5 to 10 mph.

Friday nght: Mostly cloudy. Lows in the lower 60s. West winds 5 to 10 mph.

Saturday: Mostly cloudy in the morning, then becoming partly sunny. A 40 percent chance of showers. Highs in the upper 70s. Northwest winds 5 to 10 mph.

Saturday night: Partly cloudy. Cooler with lows in the lower 50s. North winds 10 to 15 mph.

Sunday: Mostly sunny. Highs in the lower 70s.

Sunday night: Partly cloudy in the evening, then becoming mostly cloudy. Lows in the upper 40s.

Monday: Mostly sunny. Highs in the lower 70s.

Monday night: Mostly clear in the evening, then becoming partly cloudy. Lows around 50.

Tuesday: Mostly sunny. Highs in the upper 70s.

Tuesday night: Partly cloudy. Lows in the upper 40s.