Air Pollution Rises, Thunderstorms Threaten: Hudson Valley Weekend

HUDSON VALLEY, NY — As hot temperatures cause elevated levels of ground ozone, an Air Quality Health Advisory is in effect Friday in the New York City Metro and Lower Hudson Valley regions.

This advisory will be in effect through 11 p.m. The air in Rockland and Westchester counties as well as Dutchess, Orange, Putnam, Sullivan, and Ulster is unhealthy for sensitive groups — including people with cardiovascular disease and respiratory disease (such as asthma), young children, those who exercise outdoors, and those involved in vigorous outdoor work.

Consider limiting strenuous outdoor physical activity when ozone levels are the highest (generally afternoon to early evening). When outdoor levels of ozone are elevated, going indoors will usually reduce exposure. Individuals experiencing symptoms such as shortness of breath, chest pain, or coughing should consider consulting their personal physician.

The weather will be sunny, hot and humid, with constant chances for thunderstorms through the weekend and beyond across the region.

"Exact locations of the severe storms will be determined by the amount of sunshine any given area has received and that will make those areas unstable and allow strong thunderstorms to develop with hail, strong damaging wind gusts, and localized flooding," Todd Snow of Hudson Valley Weather said on Facebook. "Isolated Flash Flooding will be a major concern."

Here's the five-day forecast from the National Weather Service based on Putnam County:

• Friday - Mostly cloudy late this morning, then becoming partly sunny. A slight chance of showers late this morning, then a chance of showers and thunderstorms this afternoon. Some thunderstorms may produce gusty winds and heavy rainfall this afternoon. Highs in the mid 80s. South winds 5 to 10 mph. Chance of rain 50 percent.
• Tonight - Mostly cloudy. A chance of showers and thunderstorms in the evening, then a chance of showers with a slight chance of thunderstorms after midnight. Patchy fog after midnight. Some thunderstorms may produce gusty winds and heavy rainfall in the evening. Some thunderstorms may produce heavy rainfall after midnight. Humid with lows in the lower 70s. South winds 5 to 10 mph. Chance of rain 50 percent.
• Saturday - Patchy fog in the morning. Showers likely with a slight chance of thunderstorms in the morning, then showers likely with a chance of thunderstorms in the afternoon. Some thunderstorms may produce heavy rainfall in the morning. Some thunderstorms may produce gusty winds and heavy rainfall in the afternoon. Humid with highs in the mid 80s. South winds around 5 mph. Chance of rain 70 percent. Heat index values in the mid 90s in the afternoon.
• Saturday Night - Mostly cloudy. Showers likely with a chance of thunderstorms in the evening, then a chance of showers and thunderstorms after midnight. Patchy fog after midnight. Some thunderstorms may produce heavy rainfall. Humid with lows around 70. South winds around 5 mph. Chance of rain 70 percent.
• Sunday - Partly sunny. A slight chance of showers and thunderstorms in the morning. Patchy fog in the morning. Humid with highs in the upper 80s. North winds around 5 mph, becoming west around 5 mph in the afternoon. Chance of rain 20 percent.
• Sunday Night - Partly cloudy. Patchy fog after midnight. Lows in the upper 60s.
• Monday - Patchy fog in the morning. Mostly sunny. Highs around 90. Heat index values in the mid 90s in the afternoon.
• Monday Night - Partly cloudy. Lows in the upper 60s.
• Tuesday - Partly sunny. A chance of showers and thunderstorms in the afternoon. Highs in the upper 80s. Chance of rain 30 percent. Heat index values in the mid 90s.
• Tuesday Night - Mostly cloudy with a chance of showers and thunderstorms. Lows around 70. Chance of rain 50 percent.

Summer heat leads to the formation of ground-level ozone, a major component of photochemical smog. Automobile exhaust and out-of-state emission sources are the primary sources of ground-level ozone and the most serious air pollution problems in the northeast. This surface pollutant should not be confused with the protective layer of ozone in the upper atmosphere.

Ozone is produced indirectly when sunlight chemically reacts with nitrogen oxides and volatile organic compounds from automobile exhaust and industrial emissions. High ozone is not as visible as PM2.5 because it is a colorless gas, but will produce hazy skies and reduce visibility in high concentrations.

Ozone levels generally decrease at night and can be minimized during daylight hours by curtailment of automobile travel and the use of public transportation where available.

New Yorkers also are urged to take the following energy-saving and pollution-reducing steps:

• use mass transit or carpool instead of driving, as automobile emissions account for about 60 percent of pollution in our cities;
• conserve fuel and reduce exhaust emissions by combining necessary motor vehicle trips;
• turn off all lights and electrical appliances in unoccupied areas;
• use fans to circulate air. If air conditioning is necessary, set thermostats at 78 degrees;
• close the blinds and shades to limit heat build-up and to preserve cooled air;
• limit use of household appliances. If necessary, run the appliances at off-peak (after 7 p.m.) hours. These would include dishwashers, dryers, pool pumps and water heaters;
• set refrigerators and freezers at more efficient temperatures;
• purchase and install energy efficient lighting and appliances with the Energy Star label; and
• reduce or eliminate outdoor burning and attempt to minimize indoor sources of PM 2.5 such as smoking.

A new DEC fact sheet about the Air Quality Index is available.