New York State Department of Environmental Conservation (DEC) Commissioner Amanda Lefton and State Department of Health (DOH) Commissioner Dr. James McDonald issued an Air Quality Health Advisory for Wednesday, June 4, 2025, for ozone for the New York City Metro and Lower Hudson Valley regions.
The pollutant of concern is: Ozone
The advisory will be in effect 11 a.m. through 11 p.m.
The Wednesday, June 4, Air Quality Health Advisory regions consist of: New York City Metro, which includes New York City and Rockland and Westchester counties; and Lower Hudson Valley, which includes Dutchess, Orange, Putnam, Sullivan, and Ulster counties.
DEC and DOH issue Air Quality Health Advisories when DEC meteorologists predict levels of pollution, either ozone or fine particulate matter (PM2.5), are expected to exceed an Air Quality Index (AQI) value of 100. The AQI was created as an easy way to correlate levels of different pollutants to one scale, with a higher AQI value indicating a greater health concern.
Ozone
Summer heat can lead 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 not a direct emission, and is produced indirectly when sunlight chemically reacts with nitrogen oxides (NOx) and volatile organic compounds (VOCs) 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.
People, especially those with cardiovascular disease and those who have respiratory disease (such as asthma), young children, the elderly, those who exercise outdoors, and those involved in vigorous outdoor work should 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.
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.
Additional information on ozone and PM 2.5 is available on DEC's website and on DOH's website (PM 2.5) / DOH's website (ozone). A new DEC fact sheet about the Air Quality Index is available on DEC’s website or by PDF download.
To stay up-to-date with announcements from DEC, sign up to receive Air Quality Alerts through DEC Delivers: DEC's Premier Email Service. A toll-free Air Quality Hotline (1-800-535-1345) was also established by DEC to keep New Yorkers informed of the latest air quality situation.
