The fireworks are the point of the holiday. They are also, for a day or so, a real air-quality problem — and this year regulators are flagging it in advance.

What the advisory says

The South Coast Air Quality Management District has issued a particle-pollution advisory running from Saturday evening, July 4, through midday Sunday, July 5, LAist reported. The agency says Independence Day fireworks are expected to drive particle pollution to unhealthy levels, with the heaviest impacts Saturday night over Downtown Los Angeles, the San Gabriel Valley and northern Orange County. Much of the rest of the South Coast Air Basin — greater Los Angeles, Orange County and the Inland Empire — could see unhealthy air as the smoke spreads and settles.

Why the Fourth is bad for air

Fireworks throw off fine particulate matter, known as PM2.5 — particles small enough to slip past the body's defenses and lodge deep in the lungs. Unlike a distant wildfire plume, that smoke is generated at ground level, right where people are gathered. It also arrives during ozone season, when summer heat and strong sun cook up ground-level ozone, a separate lung irritant. The combination is what pushes a holiday night into "unhealthy" territory.

Who should be careful

Air officials single out sensitive groups: children, older adults, and anyone with asthma, COPD, other lung conditions or heart disease. For them, bad air can mean coughing, chest tightness and shortness of breath, and can aggravate existing conditions. When levels climb high enough, even healthy adults can feel it.

How to limit your exposure

The guidance from SCAQMD and federal air officials is straightforward:

  • Stay indoors when you can, especially Saturday night into Sunday.
  • Keep windows closed at home and in the car.
  • Run air conditioning on "recirculate," so it isn't pulling smoky air inside.
  • Skip strenuous outdoor exercise during the worst hours — hard breathing pulls more particles in.
  • Reconsider backyard fireworks, which add to the smoke you're trying to avoid and carry fire and injury risk in dry conditions.

If you want to watch a show, a big municipal display seen from a distance generally beats standing in the thick of neighborhood fireworks smoke.

Check before you go

Conditions vary block to block and hour to hour, so check real-time readings for your area at aqmd.gov or airnow.gov before heading out, and again before any outdoor plans on Sunday. Anyone who develops chest pain or serious shortness of breath should seek medical care. The holiday is worth enjoying — just keep an eye on the air while you do.